Standard Operational Procedure for Aviation Meteorology

India Meteorological Department

Ministry of Earth Sciences
Govt. of India
 STANDARD
OPERATIONAL PROCEDURE
FOR
AVIATION METEOROLOGY
 PREFACE
Aviation Meteorological Services is one of the oldest services provided by the India
Meteorological Department (IMD) which plays an important role in safe and efficient flight
operations to National & International sectors through civil airports in India. These
meteorological services are being provided as per the recommended and standard practices
given by International Civil Aviation Organization (ICAO) Annex-3, (Meteorological service
for International Air Navigation) & Director General of Civil aviation in India (DGCA).

In India, aviation meteorological services are provided through a network of Meteorological

Watch Offices (MWOs), functioning at four international airports namely Kolkata, New
Delhi, Chennai, and Mumbai & also through 18 Aerodrome Meteorological Offices (AMOs)
& 54 Aeronautical Meteorological Stations (AMSs) situated at various national and
international airports of the country. The MWOs are catering the needs to flights in their
respective flight information region (FIR). Regional Specialized Meteorological Centre
(RSMC), IMD New Delhi also serves as one of the ICAO designated Tropical Cyclone
Advisory Centres (TCAC) to provide Tropical cyclone advisory to the MWOs in India and
neighbouring countries for safety of aircraft movement in disaster weather. The technical
coordination and overseeing of the functions of the aviation meteorological offices in India is
done by Central Aviation Meteorological Division (CAMD) functioning at DGM New Delhi.

The web based information dissemination system known as On-line Briefing System (OLBS)
of IMD is being maintained by the meteorological offices functioning at MWOs Chennai and
New Delhi, through which the registered users can directly download the forecast products as
desired. Apart from the primary communication channels of AAI, the department has all
advanced communication modes for the dissemination of aviation information.

The aviation industry in India has emerged as one of the fastest growing industries in the
country during recent years. New airports are coming up under RCS UDRAN. So Aviation
sector has witnessed rapid growth both in terms of density of air traffic and number of airports.
This trend is expected to continue in coming years also.

In order to meet demands of growing aviation sectors & to discharge quick quality work , the
need for a consolidated Standard Operational Procedure (SOP) on aviation meteorological
services for ready use by aviation meteorological offices was felt necessary and hence the
first edition of SOP on aviation meteorological services in India has been brought out (March
2021) . The topics of this SOP are restricted to procedural aspects of meteorological service to
aviation. It is hoped that the information it contains will be very useful to the officials working
in operational field.

(Dr. M. Mohapatra)

Director General of Meteorology

 ACKNOWLEDGEMENT
The entire work of the publication has been made by a group of officers and other members
associated with aviation services of IMD. I am thankful to the authors for their tireless effort
towards formulation of the document—Standard operational procedure of aviation services. I
would like to place on record the significant contributions & guidance made by Dr.
G.C.Debnath, Sc. F & Head MWO Kolkata as chairman of the committee towards preparation,
compilation, edition, of the publication.
I express my sincere thanks and appreciation to Shri Charan Singh, Sc. F & Head MWO New
Delhi , Shri Gajendra Kumar, Sc. F & Head CAMD New Delhi , Shri S. G. Kamble , Sc. F
& Head MWO Mumbai , Shri N. Meenatchi Nathan, Sc. E & Head MWO Chennai , Shri
C.S.Tomar , Sc. E, CAMD New Delhi ,Shri Sourav Adhikary, Sc.E, MWO Kolkata , ( Member
secretary) & co- opted members Shri Sandip Sharma, Sc C, MWO New Delhi, Shri Soumak
Banerjee SA, MWO Kolkata , Shri Chiranjit Chakraborty, SA , MWO Kolkata for their
significant contribution as resource persons in preparation of this manual. I am thankful to Dr.
R.K. Jenamani Sc. F, NWFC New Delhi for reviewing and adding values to the manuscript.

(Dr. M. Mohapatra)

Director General of Meteorology

 LIST OF CONTRIBUTORS

Serial Name of Author Affiliation Topic

No.
1 Shri Gajendra Kumar & CAMD New Introduction and Overview of
Shri C.S.Tomar Delhi Aviation Service

2 Shri S.G.Kamble MWO Mumbai Standard observational

procedure
3 Shri Soumak Banerjee MWO Kolkara Climatology
4 Dr. G.C. Debnath & Shri MWO Kolkata Aviation weather forecast
Soumak Banerjee
5 Dr. G.C.Debnath MWO Kolkata Weather advisory - SIGMET
6 Dr. G.C. Debnath & Shri MWO Kolkata Aviation weather warnings
Soumak Banerjee
7 Dr. G.C.Debnath MWO Kolkata Briefing, De-briefing and
Documentation
8 Dr. G.C.Debnath MWO Kolkata Action for VIP/VVIP Flight
movement
9 Shri Sourav Adhikary & MWO Kolkata Online Briefing System
Shri Chiranjit (OLBS)
chakraborty
10 Dr. G.C. Debnath & MWO Kolkata Operational Messages
Shri Chiranjit
chakraborty
11 Shri. Chiranjit MWO Kolkata World Area Forecast System
Chakraborty & Dr. (WAFS)
G.C.Debnath

12 Shri N. Meenatchi MWO Chennai Action for Search and Rescue

Nathan Operation
13 Shri Gajendra Kumar CAMD , New Action for Aircraft Accident
Shri. C.S.Tomar Delhi and Investigation
14 Shri Soumak Banerjee MWO Kolkata Procedure of Forecast
& Verification
Dr. G.C.Debnath
15 Shri. S.G.Kamble MWO Mumbai Quality Management System
(QMS)
 TABLE OF CONTENTS

Chapter Chapter Name Page Number

1 Introduction and Overview of Aviation Service 1
2 Standard Observational Procedure 21
3 Climatology 46
4 Aviation Weather Forecast 48
5 Weather Advisory - SIGMET 73
6 Aviation Weather Warnings 77
7 Briefing, De-briefing and Documentation 83
8 Action for VIP/VVIP Flight Movement 93
9 Online Briefing System (OLBS) 99
10 Operational Messages 109
11 World Area Forecast System (WAFS) 115
12 Action for Search and Rescue Operation 129
13 Action for Aircraft Accident and Investigation 134
14 Procedure of Forecast Verification 142
15 Quality Management System (QMS) 150
Appendices
Appendix-I Notation Used in Flight Documentation 1
Appendix-II Aviation Terminology 4
Appendix-IIIList of Registers Maintained at 12
Different Aviation Met. Offices
Appendix-IV List of Templates 29
Appendix-V ICAO Abbreviation 51
 Chapter - 1
INTRODUCTION AND OVERVIEW OF AVIATION SERVICE

1.1 INTRODUCTION
Weather affects aviation activities at various stages of operation. In order to ensure
safe operations in all-weather situations, National Meteorological Services throughout
the world are obliged by law to make meteorological observations & forecasts, to
establish and maintain monitoring and warning systems in their countries. The
objective of Aeronautical Meteorology is to contribute towards the safety, economy,
regularity and efficiency of air navigation. National Meteorological Services
throughout the world make meteorological observations and forecasts through
establishment of sustained monitoring and warning systems in their respective
countries, as per the standards and guidelines provided by World Meteorological
Organisation (WMO) and International Civil Aviation Organisation (ICAO).
World Meteorological Organisation (WMO) sets standards and guidelines for
meteorological service for aviation through its Standing Committee on Services for
Aviation (SC-AVI) earlier known as Commission for Aeronautical Meteorology.
International Civil Aviation Organisation (ICAO) which is responsible for civil
aviation regulations co-operates closely with WMO in all matters related to
meteorology and common regulations are agreed to by both organisations.
India Meteorological Department (IMD) is the national agency in India, which is
responsible in all the matters pertaining to meteorology in civil aviation. Aviation
services are provided for National and International flights for safe and efficient
operations in terms of take-off, landing and en-route forecasts. These services are
provided through a network of Meteorological Watch Offices (MWOs) at four
international airports at Chennai, Kolkata, Mumbai and New Delhi and other aviation
meteorological offices. The aviation meteorological offices provide the airports
specific current weather reports, forecasts and warnings for safety, economy and
efficiency of aircraft operations.
1.2 WORLD METEOROLOGICAL ORGANISATION (WMO)
WMO is an intergovernmental organisation and acts as a specialised agency of the
United Nations (UN) for meteorology (weather and climate), operational hydrology
and related sciences. It is the UN system’s authoritative voice on the state and
behaviour of the Earth’s atmosphere, its interaction with the oceans, the climate it
produces and the resulting distribution of water resources that regulates all activities
related to meteorology and climate.
1.3 INTERNATIONAL CIVIL AVIATION ORGANISATION (ICAO)
The ICAO officially came into being on 4th April 1947. It has its Head Quarters at
Montreal, Canada. In October 1947, ICAO became the specialized agency of the
United Nations (UN). Non-governmental organizations which also participate in
ICAO’s work include the International Air Transport Association (IATA), the
Airports Council International, the International Federation of Air Line Pilot’s
Associations, and the International Council of Aircraft Owner and Pilot Associations.

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1.4 OBJECTIVE
The main purpose of ICAO is to develop the principles and techniques for
international air navigation and to foster the planning and development of
international air transport so as to:
 Ensure the safe and orderly growth of international civil aviation throughout the
world;
 Encourage the arts of aircraft design and operation for peaceful purposes;
 Encourage the development of airways, airports and air navigation facilities for
international civil aviation;
 Meet the needs of the peoples of the world for safe, regular, efficient and
economical air transport;
 Prevent economic waste caused by unreasonable competition;
 Ensure that the rights of contracting states are fully respected and that every
contracting state has a fair opportunity to operate international airlines;
 Avoid discrimination between contracting states;
 Promote safety of flight in international air navigation;
 Promote generally the development of all aspects of international civil aeronautics.
1.5 ICAO ORGANIZATION
ICAO is made up of an Assembly, a Council of limited membership with various
subordinate bodies and a Secretariat. The chief officers are the President of Council
and the Secretary General.
The General Assembly:
The sovereign body of ICAO is the Assembly and is composed of representation from
all contracting states. The Assembly meets once in every 3 years, reviewing in detail
the work of the Organization in technical, economic, legal and technical assistance
fields and setting policy for the coming years. It also votes a triennial budget.
The Council:
The governing body of ICAO is the Council. It is composed of 33 contracting states
elected by the assembly for a 3 years term. The assembly chooses the council member
states. The Council together with its sub-ordinate bodies, the Air Navigation
Commission, Air Transport Committee, The Committee on joint support for Air
Navigation Services and Finance Committee provide the continuing direction of work
of the Organization. One of the major duties of the Council is to adopt “International
Standard and Recommended Practices” and to incorporate these Annexes to the
Convention on International Civil Aviation. Both ICAO Assembly and the Council
function from ICAO’s Head Quarters at Montreal, Canada.
The Secretariat:
The Secretariat is headed by a Secretary General. It is divided into five main divisions,
the Air Navigation Bureau, the Air Transport Bureau, the Technical Assistance

2
 Bureau, the legal Bureau and Bureau of Administration and Services. Corresponding
to each ICAO committee and Division, is a Section of the ICAO Secretariat, made up
of staff members selected for technical competence in their respective fields, which
supplies technical and administrative aid to the governmental representatives who
make up the ICAO Council Committees and Divisions.
In order that the work of the Secretariat shall reflect a truly international approach,
professional personnel are recruited on a broad geographical basis. In addition to the
regular staff, the services of experts are obtained from member states.
1.6 AIR NAVIGATION COMMISSION AND METEOROLOGICAL DIVISION
The requirements of meteorological facilities for civil aviation during different phases
of operation of aircraft are discussed along with other related problems concerning
Aviation by periodical Air Navigation Conference held by ICAO. Matters of purely
meteorological interests are discussed in Meteorological Division meetings. To
coordinate action between ICAO and WMO in respect of provision of meteorological
services to civil aviation, the meetings are held conjointly with the SC-AVI (formerly
CAeM) of WMO whenever meteorological aspects are to be discussed.
1.7 THE REGIONAL ASSOCIATIONS
The aim of a Regional Association (RA) is to provide co-operation among National
Meteorological and Hydrological Services (NMHS) in a given geographical region in
dealing with special problems of a regional nature. There are six RAs, which are given
below.
 RA I: Africa
 RA II: Asia
 RA III: South America
 RA IV: North and Central America
 RA V: South west Pacific
 RA VI: Europe
India comes under RA II – Asia. The functions of RA are:
 To promote the execution of the resolutions of Congress and the Executive
Council in its Region;
 To consider matters brought to its attention by the Executive Council;
 To discuss matters of general interest and to coordinate meteorological and related
activities in its Region;
 To make recommendations to congress and the Executive Council on matters
within the purposes of the Organization; and
 To perform such other functions as may be conferred on it by Congress.
The Regional Offices:
In dealing with international civil aviation on a world wide scale, there are many

3
 subjects which ICAO has had to consider on a regional basis. The Organization has
set up eight geographical regions, both to facilitate detailed planning and to cater to
different types of flying operations. The eight regions are:
 The North American Region (NAM)
 The South American Region (SAM)
 The North Atlantic Region (NAT)
 The South Atlantic Region (SAT)
 The European Mediterranean Region (EUM)
 The Middle East Region (MID)
 The South East Asia Region (SEA)
 The Pacific Region (PAC)
India is located in MID and SEA Regions and takes part in the Regional Air
Navigation Meetings (RAN) of these regions which is held as a combined meeting.
Similar combined RAN meetings are also held by NAM & NAT and SAM & SAT.
The ICAO Regional Offices to cater to the specific aviation needs of the regions are
at Bangkok, Dakar, Cairo, Paris, Lima, Mexico City. The Regional Office at Bangkok
is concerned with the MID/SEA region and is known as the Far East Asia and Pacific
(FEAP) Office.
1.8 ICAO ADVISORY CENTRES
Volcanic Ash Advisory Centres (VAAC):
The role of a VAAC is to provide expert advice to Area Control Centres (ACCs)/
Meteorological Watch Offices (MWOs) in its area of responsibility regarding the
extent and forecast movement of a volcanic ash cloud. This information is required
by the MWOs in order to issue SIGMETs for volcanic ash. ICAO has designated the
following VAACs to provide advice to MWOs on the extent and forecast movement
of volcanic ash within an agreed area of responsibility: Anchorage (United States),
Buenos Aires (Argentina), Darwin (Australia), London (United Kingdom), Montreal
(Canada), Tokyo (Japan), Toulouse (France), Washington (United States), and
Wellington (New Zealand). In order to provide guidance to States, a set of
International Airways Volcanic Watch (IAVW) procedures has been developed by
ICAO and circulated to States in addition to the provisions in the relevant Annexes.
Tropical Cyclone Advisory Centre: It is a meteorological centre designated to
provide advisory information to meteorological watch office regarding the position,
forecast direction and speed of movement, central pressure and maximum surface
wind of tropical cyclones. The following are the Designated TCACs: Miami (USA),
Tokyo (Japan), New Delhi (India), La Reunion (France), and Nadi (Fiji).
1.9 INDIA METEOROLOGICAL DEPARTMENT– CENTRAL AVIATION
METEOROLOGICAL DIVISION (CAMD)
India Meteorological Department is the national agency which is responsible in all
matters related to provision of Meteorological support to aviation in India. The

4
 principal requirements in the aviation point of view are:
1. Supply of Current Weather Observations to all aeronautical users,
2. Issue of forecast and warnings on meteorological hazards to aviation, and
3. Adherence to procedures and formats for dissemination of products to aviators.
Service to International Civil Aviation is in accordance with the Standards and
Recommended Practices (SARPs) of ICAO (Annex 3).
Domestic Aviation (Civil, Defense, Chartered flights, Explorative missions, relief &
rescue operations, VVIP/ VIP flights, flying clubs etc.) is governed by the aviation
legislation, Civil Aviation Requirements (CAR) of Director General of Civil Aviation
(DGCA), India. It is essentially an extension of SARPs of ICAO with some National
Practices of IMD as accepted and required by the users.
1.10 CENTRAL AVIATION METEOROLOGICAL DIVISION (CAMD)
CAMD is the nodal office for the aviation services in the country. Central Aviation
Meteorological Division (CAMD) at DGM, New Delhi is the nodal office for the
aviation services in the country. It also maintains the liaison with ICAO, WMO,
Airlines, DGCA, and AAI on technical aspects of aviation. The installation and
maintenance of Airport Meteorological Instruments are done by IMD (SI) division,
Pune. The telecommunications requirements for aviation are managed by the IMD
(Telecommunication Division) functioning at New Delhi and by the
telecommunication unit of Airport Authority of India.
These services are provided through 18 Aerodrome Meteorological Offices (AMO)
and 72 Aeronautical Meteorological Stations (AMS) (including 18 AMOs) located at
various national and international airports of the country.
Aerodrome Meteorological Offices functioning at Mumbai , Kolkata , Delhi and
Chennai airports also serve as Meteorological Watch Offices (MWOs) catering to
flights in respective Flight Information Regions (FIR). One ICAO designated Tropical
Cyclone Advisory Centre (TCAC) is functioning at IMD HQ, New Delhi. It is this
center's responsibility to monitor the development of tropical cyclones in its area of
responsibility.
The guidelines for meteorological service to aviation in India are given in “Manual on
Procedures for Meteorological Services for Aviation in India” published by CAMD,
India Meteorological Department. It is essentially the Annex 3, incorporating national
practices also. The Aviation Weather Code Book, also published by CAMD, IMD
closely resembles “Manual on Codes- WMO 306”. These two publications are
updated and revised from time to time in order to incorporate all the amendments and
changes by WMO and ICAO.
1.11 FLIGHT INFORMATION REGION (FIR)
An airspace of defined dimensions within which flight information service and
alerting service are provided. Indian airspace is divided into five FIRs, namely,
Chennai, Delhi, Kolkata, Guwahati and Mumbai. The associated meteorological
office providing services to an FIR should be a MWO. However, the responsibility of
meteorological watch over Guwahati FIR is being handled by MWO Kolkata.
1.12 METEOROLOGICAL INFORMATION IN SUPPORT OF AVIATION

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 The meteorological information for the use of aviation activities are:
1. Current weather observations (METAR/ SPECI, MET REPORT/ SPECIAL).
2. Forecasts (Terminal Aerodrome Forecast (TAF), Area/ Local Forecast, Route
Forecast, Take-off and Landing (TREND) Forecast)
3. Warnings (Aerodrome warnings, Warning for Light Aircrafts, Wind shear
warnings, SIGMET)
4. Climatology (Climatology of Aerodromes, Climatological Summary, Climatology
of upper wind and temperature).
1.13 RESPONSIBILITIES OF MWO
Following are the responsibilities of Meteorological Watch Office (MWO):
1. Maintain continuous watch of meteorological conditions affecting flight
operations within its Flight Information Region (FIR).
2. Prepare SIGMET and other information relating to its FIR.
3. Exchange SIGMET information with other MWOs in the neighboring countries
namely Bahrain, Iran, Israel, Jordan, Kuwait, Oman, Pakistan, Qatar, Saudi
Arabia, Syrian Arab Republic, United Arab Emirates, Yemen, Australia,
Bangladesh, Bhutan, Cambodia, China (Beijing), Guam (US), Indonesia, Peoples
Democratic Republic of Lao, Malaysia, Maldives, Myanmar, Nepal, Philippines,
Russian Federation, Singapore, Sri Lanka, Thailand, Uzbekistan, Vietnam.
4. Supply SIGMET information and other meteorological information to associated
air traffic services units, including SIGMET messages of other MWOs.
5. Disseminate their SIGMET information to other forecasting offices in India.
6. Supply information received on pre-eruptive volcanic activity, a volcanic eruption
and volcanic ash cloud for which a SIGMET has not already been issued to its
associated Flight Information Centres (FIC)/ Area Control Centres (ACC) and to
its associated VAAC.
1.14 RESPONSIBILITIES OF AMO
Following are the major responsibilities of Aerodrome MET Office (AMO):
1. Preparation and/or obtaining forecasts, such as, output products of the world area
forecast system, and other relevant information for flights operating from their
aerodromes.
2. Preparation and/or obtaining forecasts of local meteorological conditions.
3. Keeping a continuous watch over the meteorological conditions over their local
aerodrome as well as over other aerodromes served by their associated
Aeronautical Meteorological Stations.
4. Provision of briefing, consultation and flight documentation to flight crewmembers
and/or other flight operations personnel.
5. Supply of other meteorological information to aeronautical users like-

6
 • Hourly/ half hourly current weather observations and special reports.
• RVR observations.
• Landing/Take-off reports on request for the required elements.
• Meteorological information for VOLMET broadcasts, ATIS broadcasts,
VOR broadcasts, etc.
• Pressure data.
• Radar and Satellite Observations.
• SIGMETs of FIR of which the Aerodrome Meteorological Office is a part
and SIGMETs of other FIRs.
• AIREPs available.
• METARs /SPECIs of other stations as appropriate.
• Low level wind shear and temperature inversions.
6. Display of available meteorological information.
7. Exchange of meteorological information with other meteorological offices.
8. Issue of landing and take-off forecasts.
9. Supply of flight planning information.
10. Supply of aerodrome forecasts of relevant aerodromes.
11. Supply of forecasts to their associated Aeronautical Meteorological Stations for
flights operating from their aerodromes.
12. To issue aerodrome warnings for local aerodrome as well as for their associated
Aeronautical Meteorological Stations.
13. Supply information received on pre-eruptive volcanic activity, volcanic eruption
or volcanic ash cloud to its associated air traffic services unit, aeronautical
information service unit and other MWOs and AMOs.
1.15 RESPONSIBILITIES OF AMS
Following are the major responsibilities of Aeronautical Meteorological Station
(AMS):
1. Supply to aeronautical users, of current weather observations of their own station
and those of other stations as required, by obtaining them from the stations
concerned.
2. Providing documentation for flights originating from their stations after obtaining
the forecasts from their associated Aerodrome Meteorological Office(s).
3. Supply of TAF and aerodrome warnings to aeronautical users of their aerodrome
after being received from their associated Aerodrome Meteorological Office.
4. Supply of information received on pre-eruptive volcanic activity, volcanic
eruption or volcanic ash cloud to aeronautical users.

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 5. Supply of SIGMET as and when received.
1.16 DUTIES AND TASKS OF METEOROLOGICAL OFFICER AT AIRPORT
Meteorological Watch Officer: The primary duties of a Meteorological Watch
Officer are as follows:
1. To provide Aeronautical Met Service within their area & airspace of responsibility
in accordance with the standard procedures and practices prescribed in relevant
documents.
2. Ensure that her/his unit operates efficiently and administered in accordance with
relevant provisions.
3. Keep continuous watch over the airspace bounded by the FIR boundaries and also
the adjoining FIR for weather phenomenon detrimental for Air Navigation and
take follow- up action in terms of issuance of SIGMET and amendments to
existing warning.
4. Monitoring the SIGMET of adjoining regions for transient weather phenomenon
and take timely action for their own airspace of responsibility.
5. Continuously monitor for advisories issued by Tropical Cyclone Advisory Centre,
Volcanic Ash Advisory Centre, and Space Weather Advisory Centre.
6. Continuously monitor the OPMET generated by the AMO, AMS under their area
of responsibility and intervene as per the requirements.
7. Maintain close liaison and coordination with Air Traffic Services units, ATFM,
operators and attached AMO, AMS.
Duty Officer-Meteorology: The primary duties of a Duty Officer-Meteorology are
as follows:
1. To provide Aeronautical Met Service within their area & airspace of responsibility
in accordance with the standard procedures and practices prescribed in relevant
documents which includes briefing, consultation to operators and flight crew
members.
2. Ensure that her/his unit operates efficiently and administered in accordance with
relevant provisions.
3. Maintain close liaison with Air Traffic Services units, operators, and adjoining
AMO, AMS.
4. Keeps continuous watch over the area of responsibility for weather phenomenon
detrimental for Air Navigation and takes follow-up action in terms of issuance of
forecasts, warning and amendments to existing forecast.
5. Analysis and prognosis of synoptic weather charts.
6. Issuance of routine and non-routine forecasts and warning, AD warning for
attached AMS including take-off, local forecast.
7. Preparation of Flight folder, Route forecast as per the requirements and requisition.
8. Briefing the Pilots, ATCO, and Operators about the meteorological conditions.

8
 9. Responding to telephonic queries.
10. Carrying out other station specific activities for the office.
Tower MET Officer (TMO): The primary duties of a Tower MET Officer are as
follows:
1. Observation and Recording of Aeronautical Meteorological Phenomena and
parameters in accordance with relevant provisions.
2. Ensure that her/his unit operates efficiently.
3. Keep continuous watch over the Aerodrome and vicinity for weather phenomenon
detrimental for Air Navigation.
4. Prepare routine, non-routine report and disseminates it to recipients as per the
schedule.
5. Keeps continuous watch over the performance of sensors and instruments.
6. Check and confirm the quality of meteorological observations before issuance
including relevance of content, time of validity and location of phenomena.
7. Issues TREND Forecasts. Briefs the ATCO, Duty Officer and Operators about the
prevailing meteorological Conditions and imminent changes.
1.17 AVIATION METEOROLOGICAL NETWORK IN INDIA

Figure 1: Aviation Meteorological Network

9
 1.18 IMD AVIATION ORGANISATION CHART
Central Aviation Meteorological Department

Director General of Meteorology (DGM)

Head, CAMD
(Central Aviation Meteorological Division)

MWO/AMO MWO/AMO
MWO/AMO MWO/AMO
Kolkata
Chennai Mumbai New Delhi

AMO
NWFC Tropical Cyclone AMO Agartala AMO National MET
(TCAC) Advisory AMO Jaipur Training and Continued
Bangalore Ahmedabad Education Training
AMO Institute
AMO Bhubaneswar AMO
Surface AMO Bhopal
Instruments AMI
Hyderabad Lucknow
Maintenance AMO Aviation Climatology AGDM
Division Training
Guwahati AMO Nagpur (Research)
AMO
Thiru’puram
AMO Aeronautical
Telecom Aeronautical MET
Telecom Training
Dibrugarh MET Stations SATMET
Division Satellite Products and
Aeronautical Training Division
Aeronautical MET Stations
MET Stations AMO Patna
Upper Air Upper Air Instruments
Instruments Radar/Training

Division

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 1.19 LIST OF INSTALLED INSTRUMENTS AT AIRPORTS
Type of the Instrument RVR
Airport
Serial
(ICAO Name
No. Vaisala Telvent DCWIS DIWE CWIS Drishti Telvent
Code)

1 VIAR AMRITSAR 3 2
2 VEBN VARANASI 1 1
3 VOCL KOZHIKODE 1 1
4 VIGG GAGGAL 1
5 VOHS HYDERABAD 2 2 2
6 VEAT AGARTALA 1
7 VOCP CUDDAPAH 1
8 VOHY BEGUMPET 1
9 VAJB JABALPUR 1
10 VILD LUDHIANA 1
11 VOMD MADURAI 1
12 VOML MANGALORE 1 1
13 VEMN DIBRUGARH 1
14 VIPT PANTNAGAR 1
15 VORY RAJAHMUNDRY 1
16 VOSM SALAM 1
17 VOTP TIRUPATI 1
18 VOBZ VIJAYAWADA 1
19 VELP LENGPUI 3
20 VEPT PATNA 1 1 1
21 VEGY GAYA 1 1
22 VECC KOLKATA 3 1 3
23 VOBL BANGALURU 1 1 1
24 VAKE KANDLA 1
25 VOND NANDED 1
26 VAUD UDAIPUR 1
27 VEDG DURGAPUR 1
28 VISM SHIMLA 1
29 VERB FURSATGANJ 1
30 VIJP JAIPUR 1 3 1
31 VANP NAGPUR 1 1
2 2 2
32 VABB MUMBAI
1 1 1
33 VAAH AHMEDABAD 1
34 VAPR PORBANDER 1
35 VADU DIU 1
36 VASU SURAT 1
37 VABO VADODARA 3
38 VEBI SHILLONG 1
39 VAJL JALGAON©

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40 VASD SHIRDI 1
41 VASL SOLAPUR
42 VAJJ JUHU 1
43 VABV BHAVNAGAR 1
44 VEKS KESOD
45 VOAT AGATTI 1
46 VOTV TRIVANDRUM 1 1
47 VELR LILABARI 1
48 VERC RANCHI 1
49 VEIM IMPHAL
50 VOCB COIMBATORE 1
51 VIBR BHUNTAR 1
52 VIDN DEHRADUN 1 1
53 VOBM SAMBRA 1
54 VOTR TIRUCHIRAPPALLI 1
2 2 1
55 VOMM CHENNAI
1 0 0
56 VARK RAJKOT 1
1 2 2
57 VIDP DELHI 2 6
2 5 3
58 VEPY PAKYONG
59 VEBS BHUBNESWAR 1
60 VABP BHOPAL 1
61 VIKO KOTA
62 VEJR JAGDALPUR
63 VEJH JHARSUGUDA
64 VOPC PUDDUCHEREY 1
65 VIHR HISAR 1
66 VIPT PITHORAGARH 1
67 VIDD SAFDARJUNG 1
68 VOHB HUBLI 1
69 VOTK TUTICORIN 1
70 VIKG KISHANGARH 1
71 VOKN KANNUR 1
72 VOMY MYSORE 1
73 VEJS JAMSHADPUR 1
74 VAAU AURANGABAD 1
75 VAKP KOHLAPUR
76 VIRP ROHINI 1
77 VILK LUCKNOW 1 3
78 SINDHDURG
79 VOCI KOCHI 1 1
80 VERP RAIPUR 1
81 (IA
GUWAHATI 1 1
VEGT AMS)

12
82 VAGD GONDIA 1 1
83 VAID INDORE 3
84 VEKO KHAJURAHO 1
85 VECO COOCH-BEHAR 1
86 VEMR DIMAPUR 1
87 VOPN PUTTAPARTHI
88* VOBG BANGALORE(HAL) 1

*88-Puttaparthi (VOPN): Annual number of flight operations is about 20-25. Feb

2019 had only total of 2 flights. Met instruments available: Max, Min, DB, WB, ORG,
Aneroid Barometer, CCA, and Wind wane, IMD ARG. NO DIWE or CWIS. Presently
they employ retired IMD or IAF met officer’s per visit basis whenever flights are
scheduled.
1.20 ROUTINE REPORTS
The following routine reports are to be forwarded to CAMD:

Serial Description of Reports Originating Periodicity of Schedule of Report

No. /Returns Office Report to Reach CAMD
1 Statement verification of All AMOs Monthly By 10th of following
Aviation Forecast month
2 Statement of verification of All AMOs Monthly By 10th of following
Aerodrome Warning month
3 Statement of Verification of All AMOs Monthly By 10th of following
Trend Forecast month
4 Statistics of Aviation Forecast All AMOs Monthly By 10th of following
month
5 Delay in reception of Aviation All AMOs Quarterly By 10th of following
Met. Messages month
6 Implementation of Aviation All AMOs/ AMSs Monthly By 10th of following
Circulars month
7 Amendment to AIP India All RMCs Quarterly After 15 days of Quarter
ending
8 Half yearly TAF Statement All AMOs Half Yearly After 15 days of half Year
ending
9 Installations and working status All AMOs and Monthly By 5th of following month
of AMI AMSs
10 List of in-charges of Aviation All RMC’s Half Yearly By 10th of Jan and July
Met. Offices Every year
11 Changes in Handbook Pages All AMOs and As and When
AMSs Required
12 Random Scrutiny of Forecasts DDGM (RMC) Monthly 15th of the following
month
13 List of Officers for undertaking RMC Annual By end of January every
Familiarization Flight year

13
1.21 TIMING OF THE AIRPORT MET SERVICES AVAILABLE AT ACT AND
STATUS CURRENT WEATHER INSTRUMENTS

Major airports (MWO/AMOs):

Serial Name of the MWO/ Instruments Available/Installed

No. Operation hours/
ICAO Index
1 Chennai RWY07 IAAMS
H24/VOMM RWY25 DCWIS + TXM
RWY12/30 DCWIS+TXMD
2 Delhi RWY28 DCWIS + TXMD, Flamingo
H24/VIDP RWY10 & RWY09 DCWIS + TXM
RWY27 IAAMS, TXMD
RWY 29 IAAMS, TXMD&29MID TXM, TXMD,
RWY29 beg TXMD
RWY11IAAMS TXMD
RWY11beg TXMD
3 Kolkata RWY01R DCWIS +TXM Vaisala
H24/VECC RWY19L mid TXM Vaisala
RWY19L DCWIS+ TXM Vaisala
RWY19R TXMD
4 Mumbai RWY27 IAAMS, TXM
H24/VABB RWY09 IAAMS, TXM
RWY14 IAAMS, TXM

Other major AMOs:

Serial Name of the AMO / Instruments Available/Installed
No. Operation hours / ICAO
index
1 Bangalore RWY27IAAMS
H24 / VOBL RWY09DCWIS + TXM
2 Shamshabad RWY27 IAAMS
H24 / VOHS RWY09 DCWIS +TXM
3 Thiruvananthapuram RWY32DCWIS
H24 / VOTV
4 Delhi Safdarjung DIWE
H24 / VIDD
5 Jaipur RWY27IAAMS
H24 / VIJP RWY 09& MID  TXM
6 Lucknow RWY27 DCWIS+ TXM
H24 / VILK RWY 09&MID TXMD

14
 7 Agartala DIWE
H24 / VEAT
8 Bhubaneshwar DIWE +TXM
H24/ VEBS
9 Patna DIWE+TXM
H24 / VEPT
10 Mohanbari RWY DIWE
H24/ VEMN
11 Guwahati RWY02 IAAMS +TXM
H24 / VEGT
12 Nagpur AMO RWY32DCWIS
H24 / VANP
13 Bhopal AMO DIWE
H24 / VABP
14 Ahmedabad RWY23 DCWIS+TXM
H24 / VAAH RWY05 DIWE

Other major AMSs:

Name of the AMS/

Serial
Operation Hours/ Instruments Available/Installed
No.
ICAO index
1 Agatti
H07 / VOAT
2 Bengaluru HAL RWY27
H24 / VOBG
3 Belgaum
H24 / VOBM
4 Coimbatore DIWE
H24 / VOCB
5 Hubli DIWE
H07 /VOHB
6 Hyderabad
H24 / VOHY
7 Kochi CIAL
H24 / VOCI
8 Kozhikode / Calicut RWY28
H24 /VOCL
9 Madurai DIWE
H24 / VOMD
10 Mangalore DCWIS
H24 /VOML DIWE at 2 ATC towers + TXM

15
11 Mysore DIWE
H07 / VOMY
12 Pondicherry CGA Wind
H07 / VOPC
13 Rajahmundry DIWE
H14 / VORY
14 Salem DIWE
H07 / VOSM
15 Tiruchirapalli DIWE
H24 / VOTR
16 Tirupati DIWE
H14/ VOTP
17 Tuticorin DIWE
H07 / VOTK
18 Vijayawada
H07/ VOBZ
PAB/Portable Kit/Conventional Instrument Owned
19 Puttaparthi
by Airport Operator
(HO/NB) / VOPN
20 Cudappah Portable kit
H07/VOCP
21 Amritsar
H24 / VIAR
22 Bhuntar (Kulu) DIWE
H07 / VIBR
23 Dehradun DIWE + TXM
H07 / VIDN
24 Fursatganj(Raebareli) Surface Instrument
H14 / VIRB
Gaggal
25 DIWE
(DharmasalaKangra)
H07 / VIGG
26 Kota Surface Instrument
H14/ VIKO
27 Ludhiana Surface Instrument
H07 / VILD
28 Pantnagar Surface Instrument
H07 / VIPT
29 Udaipur DIWE
H14 / VIUD
30 Varanasi DIWE +TXM
H24 / VIBN

16
31 Shimla DIWE
NB / VISM
32 Aizwal (Lengpui) DIWE
H14 / VEAZ
33 Cooch-behar DIWE
H14 / VECO
34 Dimapur DIWE
H14 / VEMR
35 Gaya DIWE
H14 / VEGY
36 Imphal DIWE
H14 / VEIM
37 Jamshedpur DIWE
H14 / VEJS
38 North Lakhimpur DIWE
H07 / VELR
39 Passighat Surface Instrument
H14 / VEPG
40 Ranchi DIWE
H14 / VERC
41 Shillong (Barapani) DIWE
H14 / VEBI
42 Durgapur IAAMS
H07/VEDG
43 Aurangabad DIWE
H24 / VAAU
44 Bhavnagar DIWE
H14 / VABV
45 Diu DCWIS
(HO/NB) / VADU
46 Gondia DCWIS, DIWE
(HO/NB) / VAGD
47 Indore DIWE
H24 / VAID
48 Jabalpur ?Surface
(HO/NB) / VAJB
49 Juhu Mumbai HAWOS
H14 / VAJJ
50 Kandla DIWE
H14 / VAKE
Khajuraho DIWE
51
(HO/NB) / VAKJ

17
 52 Nanded DCWIS
(HO/NB) / VOND
53 Porbandar DIWE
H07 / VAPR
54 Raipur DIWE
H14 / VARP
55 Rajkot DIWE
H07 / VARK
56 Surat DIWE
H07 / VASU
57 Vadodara DIWE
H07 / VABO

1.22 VARIOUS FORECASTS/WARNING SERVICES AVAILABLE AT

DIFFERENT AIRPORTS
Serial
AIRPORT NAME FORECASTs
No.
1 VIAR AMRITSAR TREND
2 VEBN VARANASI TREND
3 VOCL KOZHIKODE TREND,AD
4 VIGG GAGGAL NIL
5 VOHS HYDERABAD TREND,LOCAL,AREA,AD
6 VEAT AGARTALA LOCAL,AREA,TAKEOFF,AD,TAF
7 VOCP CUDDAPAH NIL
8 VOHY BEGUMPET LOCAL,AREA,AD
9 VAJB JABALPUR NIL
10 VILD LUDHIANA NIL
11 VOMD MADURAI TREND,LOCAL,AD
12 VOML MANGALORE TREND
13 VEMN DIBRUGARH TREND,TAKEOFF,LOCAL,AD,TAF
14 VIPT PANTNAGAR NIL
15 VORY RAJAHMUNDRY TREND
16 VOSM SALAM TREND
17 VOTP TIRUPATI LOCAL,AREA,AD
18 VOBZ VIJAYAWADA TREND,TAF
19 VELP LENGPUI TREND,AD
20 VEPT PATNA TREND,LOCAL,AREA,AD,TAF
21 VEGY GAYA TREND
22 VECC KOLKATA TREND,LOCAL,AD,TAF,SIGMET
23 VOBL BANGALURU TREND,AREA,LOCAL,AD,TAF
24 VAKE KANDLA NIL
25 VOND NANDED TREND,AREA,LOCAL

18
26 VAUD UDAIPUR TREND
27 VEDG DURGAPUR TREND,AD
28 VISM SHIMLA NIL
29 VERB FURSATGANJ NIL
30 VIJP JAIPUR TREND,AREA,LOCAL,TAKEOFF,AD,TAF
31 VANP NAGPUR TREND,AREA,TAKEOFF,AD
32 VABB MUMBAI TREND,LOCAL,AD,TAF,SIGMET
33 VAAH AHMEDABAD LOCAL,TAKEOFF,AD,TAF
34 VAPR PORBANDER NIL
35 VADU DIU NIL
36 VASU SURAT NIL
37 VABO VADODARA TREND
38 VEBI SHILLONG NIL
39 VAJL JALGAON NIL
40 VASD SHIRDI NIL
41 VASL SOLAPUR NIL
42 VAJJ JUHU TREND,LOCAL,AD
43 VABV BHAVNAGAR NIL
44 VEKS KESOD NIL
45 VOAT AGATTI TREND,AD
46 VOTV TRIVANDRUM TREND,LOCAL,AREA,AD,TAF
47 VELR LILABARI NIL
48 VERC RANCHI TREND
49 VEIM IMPHAL TREND,AD
50 VOCB COIMBATORE TREND,LOCAL,AD
51 VIBR BHUNTAR NIL
52 VIDN DEHRADUN NIL
53 VOBM SAMBRA NIL
54 VOTR TIRUCHIRAPPALLI TREND,AD
TREND,LOCAL,AREA,TAKEOFF,
55 VOMM CHENNAI
AD,TAF,SIGMET
56 VARK RAJKOT NIL
TREND,LOCAL,AREA,TAKEOFF,
57 VIDP DELHI
AD,TAF,SIGMET
58 VEPY PAKYONG NIL
59 VEBS BHUBANESHWAR TREND,LOCAL,AD,TAF
60 VABP BHOPAL NIL
61 VIKO KOTA TREND
62 VEJR JAGDALPUR NIL
63 VEJH JHARSUGUDA NIL
64 VOPC PUDDUCHEREY TREND,AD,TAF
65 VIHR HISAR NIL
66 VIPT PITHORAGARH NIL

19
67 VIDD SAFDARJUNG TREND,AREA,LOCAL,AD
68 VOHB HUBLI TREND,LOCAL,AD
69 VOTK TUTICORIN TREND,AD
70 VIKG KISHANGARH NIL
71 VOKN KANNUR TREND,AREA,AD
72 VOMY MYSORE NIL
73 VEJS JAMSHADPUR NIL
74 VAAU AURANGABAD NIL
75 VAKP KOHLAPUR NIL
76 VIRP ROHINI NIL
TREND,LOCAL,AREA,
77 VILK LUCKNOW
TAKE OFF,AD,TAF
78 SINDHDURG NIL
79 VOCI KOCHI TREND
80 VERP RAIPUR TREND
81 VEGT GUWAHATI TREND,TAF,AD,LOCAL,TAKE OFF
82 VAGD GONDIA NIL
83 VAID INDORE TREND
84 VEKO KHAJURAHO NIL
85 VECO COOCH-BEHAR NIL
86 VOBG BANGALORE(HAL) NIL
87 VEMR DIMAPUR NIL
88* VOPN PUTTAPARTHI NIL

20
 Chapter - 2
STANDARD OBSERVATIONAL PROCEDURE

2.1 INTRODUCTION
A set of step-by-step instructions to help Aviation Meteorological Observers to carry
out routine monitoring, observing and reporting of weather elements. SOPs aim is to
achieve efficiency, quality output and uniformity of performance in compliance with
the regulations laid-in.
As per ICAO the duty of AMO is performed by a Meteorological Technician.
“He is a person who has successfully completed the Basic Instruction Package for
Meteorological Technicians (BIP-MT).”
In IMD’s context the duty of AMO (Aeronautical Meteorological Observers) is
performed by Scientific Assistant or Meteorologist – A / B
They have been re-designated as Tower Met Officer.
Aeronautical Meteorological Observers duties and responsibilities:
Monitor continuously the weather situation;
Observe and record aeronautical meteorological phenomena and parameters;
Ensure the quality of the performance of systems and of meteorological information;
Communicate meteorological information to internal and external users.
In addition to taking and disseminating accurate, scheduled observations, the observer
must report significant changes in weather conditions that could have an adverse effect
on safe and efficient aviation operations. Observations should be taken and
disseminated as rapidly and accurately as feasible to report these changes when they
are observed. The observer shall disseminate corrected reports immediately upon
discovering an error as per guidelines.
Service to Aviation is one of the most important activities of India Meteorological
Department. Meteorological support contributes towards the safety, economy,
regularity and efficiency of aviation operations. Towards achieving these objectives,
an aeronautical observer is required to constantly monitor the meteorological
conditions at the aerodrome and its vicinity and make routine meteorological
observations at fixed intervals and to make special observations whenever specified
changes occur. They should have skills and knowledge in the use of aviation specific
codes and practices also. As specified by WMO in its Document No. 258 Supplement
No.1, AMO should have the following knowledge and skills in order to carry out their
duties and tasks:
(a) Surface observations: Make surface meteorological observations; observe and
record the parameters that make up a meteorological message; encode the
observations in the standard format; transmit coded information.
(b) Weather watch: Analyse observations in the local area and be in a position to
identify probable significant changes in weather at the station; know and understand

21
 the region-specific weather phenomena; be aware of likely weather sequences that are
expected to affect the station.
(c) Weather alert: Understand a basic weather briefing or forecast, so as to be able
to identify changes from the expected evolution at the station; alert the duty forecaster
and external users to observed changes in the weather within the local area.
(d) Product distribution: Distribute data and information; disseminate messages to
users; issue routine and non-routine reports in accordance with normal working
practice; answer questions from users.
(e) Equipment maintenance: Carry out routine maintenance of observing/ office
equipment; operate and maintain automated weather stations, as appropriate.
All the airports have been provided with automated / manual equipment for measuring
or assessing and for monitoring and remote indicating of surface wind, visibility,
runway visual range, air and dew-point temperatures and atmospheric pressure to
support approach and landing and take-off operations. At Amritsar, Bangalore,
Chennai, Guwahati, Jaipur, Mumbai, New Delhi, and Hyderabad airports, integrated
automatic systems have been installed for acquisition, processing, dissemination and
display in real time of the meteorological parameters.
2.2 OBSERVATION & REPORTING OF WEATHER FOR AVIATION
SERVICES
METAR and SPECI:
METAR and SPECI are weather reports encoded from the airport weather
observations. METAR is the name of the code for an aviation routine weather report.
A METAR is issued at half- hourly intervals in India. SPECI is the name of the code
for an aviation special weather report. A SPECI can be issued at any time when certain
criteria are met. Both METAR and SPECI have the same code form and both may
have a TREND forecast appended. METAR and SPECI are disseminated beyond the
aerodrome of origin.
Reports of routine observations are also issued as Local Routine Reports, only for
dissemination at the aerodrome of origin. These are issued to local ATC units on white
paper in abbreviated plain language and identified by the prefix “MET REPORT”.
Similarly reports of special observations (conditions are given in a separate section)
are also issued for local use as local special reports on red colour paper in abbreviated
plain language. They are identified by the prefix “SPECIAL”.
Contents of Reports:
Content and order:
METAR or SPECI and MET REPORT and SPECIAL, ADDITIONAL contain the
following information in the given order.
1. Identification of the type of report
2. Location indicator
3. Time of Observation
4. Identification of an automated or missing report, when applicable

22
5. Surface Wind (Direction and Speed)
6. Visibility
7. Runway Visual Range (if available)
8. Present Weather
9. Cloud amount, cloud type (only for cumulonimbus and towering cumulus clouds)
and height of cloud base or where measured, Vertical Visibility
10. Air Temperature and Dew Point Temperature
11. Pressure- QNH and, when applicable, QFE (QFE included only in local routine
and special reports)
12. Supplementary Information (included in accordance with regional air navigation
agreement)
13. RMK group
CAVOK: The code word CAVOK is used to replace the visibility, present weather
and cloud groups when the following conditions occur simultaneously at the time of
observation:
(a) The visibility is 10 km or more;
(b) There is no cloud of operational significance; (cloud of operational significance:
A cloud with the height of cloud base below 1500m (5000ft) or below the highest
minimum sector altitude, whichever is greater, or a Cumulonimbus cloud or a
towering cumulus cloud at any height);
(c) There is no significant weather phenomenon.
RMK group: At the end of a METAR or SPECI a section starting with the code word
RMK may be appended. This section contains information required by the national
authority of each country and is not disseminated internationally.
As per ICAO, issuance of SPECI is not necessary if METAR are issued at half-hour
intervals. India had stopped issuing SPECI w.e.f. 15th Nov. 2015 (00Z) (ORDER
enclosed SPECI and Additional Reports for reference)
Additional Reports:
Aviation Circular 2/2015/CA-080300/2015
India Meteorological Department
Central Aviation Meteorological Division (CAMD)
Office of the Director General of Meteorology, New Delhi
Sub: Revised criteria for additional Reports.
The following changes are to be made in para 4.8 Additional Reports of the 4th Edition
(2012) of ‘Manual on Meteorological Services for Aviation in India’. The criteria for
Additional reports is changed to include visibility changes to or passes 550m, 1200 m
and 2500m. Accordingly para 4.8 will be changed as given below:

23
 This message is identified with the prefix “ADDITIONAL” and supplied on red color
paper. However, these are not disseminated outside the aerodrome of origin. These
are issued to local ATC units in addition to the local routine reports and local special
reports.
ADDITIONAL reports shall be issued for changes in cloud base height and visibility
by all aeronautical meteorological offices in India as per the following criteria:

Element Criteria Issued by

Cloud Base Whenever the height of base of All stations equipped with
cloud covering more than half the ceilometers/ ceilographs.
sky changes to or passes 90 or 120
m (300 or 400 ft)
Visibility Whenever visibility changes to or By all Aerodrome
passes 550, 1200, 2000, 2500 and Meteorological Offices/
4000 meters. aeronautical meteorological
stations recording routine
observations.

2.3 METAR/SPECI CODE FORM

2.3.1 IDENTIFICATION GROUPS
METAR or COR CCCC vyggggz NIL (AUTO)
This has three parts:
1. The Report code Name (METAR or SPECI and MET
REPORT/SPECIAL/ADDITIONAL)
2. The ICAO location indicator of the reporting station, e.g. VOMM (Chennai
Airport)
3. The day of the month and the time of the observation in hours and minutes UTC,
followed by the letter Z. Example: 211030Z (CW observation of 21st day of the
month and time of observation 1030 UTC).
The code words COR and NIL are to be inserted after the code name and the time
group, for indicating a corrected message or as an indication of a NIL message.
Usually NIL is not being used in India.
The indicator AUTO is inserted when the report contains a fully automated
observation, that is, without human intervention. But in India it is not being practiced.
2.3.2 Surface Wind (KMH or KT or MPS)
Code Format: dndndnVdxdxdx
Reporting steps: Knots (KT) is the primary unit used in India for reporting wind
speeds in aviation messages. The mean true direction in degrees rounded off to the
nearest 10 degrees from which the wind is blowing and the mean speed of the wind
over the 10-minute period immediately preceding the observation shall be reported for

24
dddff followed, without a space, by the abbreviation KT. Values of wind direction less
than 100o shall be preceded by 0 and a wind from true north shall be reported as 360.
Values of wind speed less than 10 units shall be preceded by 0.
Reporting: Normally there will be a five-figure group to indicate the ten-minute mean
wind followed by an abbreviation to indicate the wind speed units used. The first three
figures indicate the wind direction and the last two the wind speed.
Example: 31015KT, 09008KT
Averaging periods for wind observations:
1. The wind reported in METAR and SPECI should be the mean over the ten minutes
preceding the observation. If during this period there has been a marked
discontinuity lasting at least two minutes, the mean values should be assessed over
the period after the discontinuity. A marked discontinuity occurs when there is a
wind direction change of 30 degrees or more with a wind speed of 10kt or more,
before or after the change or a wind speed change of 10 kt or more.
2. The averaging period for measuring variations from the mean wind speed (gusts)
should be three seconds.
3. For inclusion in MET REPORT and SPECIAL and for displays in air traffic
service units, two minutes averaged wind is used.
Wind Reporting- Special Cases:
1. In the case of variable wind direction, ddd shall be encoded as VRB when the
mean wind speed is less than 3 knots. A variable wind at higher speeds, shall be
reported only when the variation of wind direction is 180° or more or when it is
impossible to determine a single wind direction, for example when a thunderstorm
passes over the aerodrome.
Example: VRB02KT (variable wind with mean wind speed of 2 knots)
VRB20KT (mean wind speed is 20 knots the wind direction is varying by 180° or
more)
In MET REPORT as “WIND VRB2KT” and as “WIND VRB28KT”
2. If, during the 10-minute period preceding the observation, the total variation in
wind direction is 60° or more but less than 180° and the mean wind speed is 3
knots or more, the observed two extreme directions between which the wind has
varied shall be given for dndndnVdxdxdx in clockwise order. The wind shall be
reported in METAR/ SPECI as 31015KT 280V020. (Clockwise variation of wind
from 280° to 20°) In local reports, it shall be reported as “WIND 310/15KT VRB
BTN 280/ AND 020/”
3. Variation from the mean wind speed (gusts) during the past ten minutes shall be
reported when the maximum wind speed exceeds the mean speed by 10 knots or
more. The wind shall be reported in METAR/ SPECI as 31015KTG30KT. In
METREPORT it shall be reported as WIND 310/15KT MAX 30 MIN 5.
4. When a wind speed of less than 1 knot is reported, it shall be indicated as calm.
"Calm" shall be coded as 00000 followed immediately, without a space, by the

25
 abbreviation KT, in the form 00000KT. In MET REPORT it shall be indicated as
WIND CALM.
5. In MET REPORT and SPECIAL, if the surface wind is observed from more than
one location along the runway, the locations for which these values are
representative should be indicated.
Example: WIND RWY 27 TDZ 240/16KT MAX27 MNM10 END 250/14KT
Estimating Wind Speed Alternative method:
If the wind direction indicator is inoperable, estimate the direction by observing the
wind cone/ wind sock.
Use the Beaufort scale, to estimate wind speeds if instruments are out of service. Gusts
and squalls are not to be estimated.
Use Portable Airport Met Instruments Kit Provided
2.3.3 Visibility:
Code Format: VVVVDv VxVxVxVxDv
When there is NO marked directional variation in visibility, the minimum visibility
will be reported in metres using four figures. The visibility is assessed manually with
the help of visibility polar diagrams.
Example: 4000 (Four thousand metres)
Reporting:
Visibility shall be reported as follows:
1. In steps of 50M when the visibility is less than 800M,
2. In steps of 100M, when it is 800M or more but less than 5 km;
3. In kilometers steps when the visibility is 5km or more but less than 10km;
4. As 10 km when the visibility is 10 km or more, except when the conditions for the
use of CAVOK apply.
Any observed value, which does not fit the reporting scale in use, shall be rounded
down to nearest lower step in the scale.
Directional variations:
Directional variations are NOT considered MARKED unless the minimum visibility
is less than 5000M and the variations are at least 50 percent of the minimum visibility.
When there is a marked directional variation in the visibility, the reported minimum
visibility will be followed by one of the eight points of the compass to indicate the
direction of this visibility.
Example: 4000NE (Four thousand meters to the North East)
If the lowest visibility is observed in more than one direction, then the most
operationally significant direction shall be reported.

26
 Exception: When the minimum visibility is less than 1500 m and the visibility in
another direction is more than 5000 m, the maximum visibility and its direction should
also be reported.
Example: 1400SW 6000N (One thousand four hundred metres to the Southwest and
6 km to the North)
If the maximum visibility is observed in more than one direction, then the most
operationally significant direction is reported.
Manual Visibility estimating aid: Visibility landmarks and Polar diagram for both
day and night visibility prepared using standard procedures and made available at the
station.
Dark or nearly dark objects viewed against the horizon sky during the day, or
unfocused lights of moderate intensity (about 1000 candela) during the night.
At all stations, for METAR and SPECI, the visibility shall be the lowest observed
around the point of observation.
2.3.4 Runway Visual Range:
Code Format: rdrdr/vrvrvri or rdrdr/vrvrvrvrvvrvrvrvri
The group starts with the letter R followed by the Runway designator DRDR and a
“/” followed by the RVR in metres. Up to a maximum of four groups may be reported
in METAR.
Example: R24/1100 (Runway visual range on Runway 24, greater than one thousand
one hundred metres)
Directional variation of RVR as indicated in rdrdr/vrvrvrvrvvrvrvrvri is not reported
in India.
Special Case:
1. When the RVR is assessed to be more than 2000 m it should be reported as P2000.
Example: R24/P2000 (Runway visual range on Runway 24, greater than 2000
metres). In MET REPORT, it will be reported as “RVR RWY 24 ABV 2000M”.
2. When the RVR is below the minimum value that can be assessed the RVR should
be reported as M followed by the appropriate minimum value that can be assessed.
Example: R24/M0050 (Runway visual range on Runway 24, less than one hundred
and fifty metres). In MET REPORT it is reported as RVR RWY 24 BLW 50M.
Reporting and reporting scales:
In METAR and SPECI, where there is more than one runway available for landing,
touchdown zone runway visual range values shall be included for all such runways,
up to a maximum of four.
In local reports, the available runway visual range values shall be reported indicating
the locations, in the order touchdown zone, mid and end.
Reporting scales of RVR are as follows:
1. Increments of 25 m, if RVR below 400 m

27
2. Increments of 50 m, if RVR between 400 and 800 m
3. Increments of 100 m, if RVR above 800 m
Any observed value, which does not fit the report scale in use, shall be rounded down
to the nearest step in the scale.
National practice:
Runway visual range observations should be made, and reported in current weather
reports, throughout periods when either the horizontal visibility or the runway visual
range is less than 1500m.
Whenever the general visibility and / or RVR is from 1500 m to 2000 m, the RVR
should be included in the METAR/SPECI and in local routine and special reports as
supplementary information under “RMK” group.
This supplementary information is not to be disseminated internationally.
If the horizontal visibility is 2000 m or less but RVR is more than 2000 m the same
shall be reported as “RVR ABV 2000 M” as supplementary information, with
indicator RMK.
Manual RVR:
Whenever the visibility become 1500m or less, all aviation forecasting offices should
take manual RVR observation if instrumental recording facility of RVR is not
available or is not functioning.
When the visibility is expected to reach 1500m or fall below 1500m, the ATC should
be asked to provide transport with communication facility. An observer should be sent
to the observing point for RVR observations as soon as the transport is made available
by ATC. The current runway end in use, Touch down Zone (TDZ) should be
ascertained from ATC well in advance and the observer should be sent to the
corresponding observing point of runway in use to take RVR observations. Where
runway visual range is determined by human observers, runway visual range should
be reported to the appropriate local air traffic services units, whenever there is a
change in the value to be reported in accordance with the reporting scale. The
transmission of such reports shall normally be completed within 15 seconds after the
termination of observation.
Reporting Of Manual RVR:
Visual observations using lights:
In the visual observations method using lights, the RVR should ideally be assessed at
a height of 5 m above the centre line of the runway and the observer should count
runway lights from the runway threshold or from the touchdown zone. If it were
possible to assess RVR this way, the observing position would correspond best to what
the pilot sees. However, during flight operations, the observer, with the observation
vehicle, must be removed from the runway and its immediate area. Because it is also
necessary for continuous RVR information to be available to the pilot during flight
operations, it is clear that human RVR assessments cannot be made from the runway
itself. Instead, an observing position is chosen so that continuous RVR assessment can
be carried out from a safe location. Moreover, RVR observing structures are made as
frangible as possible consistent with their purpose. In all applications of human

28
observer RVR systems, the observers should meet a specified vision standard and be
subject to periodic vision checks. If no suitable platform is available as observing
point, a jeep can be taken to the observing location and standing over the bonnet of
the jeep, the observer counts the number of runway edge lights. As the distance
between two lights is known, it is possible to assess the RVR.
Normally, the runway edge lights on the side of the runway opposite the observing
position are counted; centre line lights, being flush fittings, are not sufficiently visible
therefrom. (Furthermore, runways with centre line lights tend to be equipped with
instrumented RVR systems) Using the far side lights provides a better assessment of
conditions along the runway than would be achieved by using the same side lights. In
a basic human observer system, the straight line distance from the observing position
to each light is measured and this becomes the reported RVR, but this method has
considerable inaccuracy. The edge lights are usually 60 m apart, except at taxiway
intersections, where the distance is different (e.g. 120 m). The RVR assessed visually
is the distance in the runway direction between the observer and the furthest visible
edge light. A simple conversion table is often compiled relating the number of
observed lights to RVR to be reported.
Counting runway edge lights that are visible on either the near or far side of the runway
is a difficult task because the edge lights may become confused with other white lights
on the aerodrome; also, the observer’s perception of the spacing between lights
becomes progressively less as range increases making it difficult to accurately count
the number of lights. Therefore, some States use separate lights — identical to the
runway lights in use and varied in intensity in the same way — for assessing RVR.
Because the observer and the light rows used are beyond the obstacle limits, RVR
assessments can be made during flight operations provided that these lights do not
give false indication of the runway position to pilots (see Annex 14, 5.3.1.2). Some
systems include the possibility of switching separate lights on and off to assist the
observer. The use of separate light rows requires special calibration procedures (see
10.3), which may be difficult to perform. These kind of lights also need periodic
cleaning like the runway lights.
Calibration of Visual Observations:
Because the RVR assessment point is different from that located at a height of 5 m
above the centre line of the runway, a calibration of the system must be carried out.
The direct method of calibrating the RVR observations is to make simultaneous
observations from the Runway Observing Point (ROP) and from the corresponding
touchdown point on the central line of the runway during poor visibility conditions
when there is no air traffic. If no suitable platform of 5 meter height is available, the
bonnet of another jeep can be used for locating the observer at central line. Now the
two observers are count the number of edge lights- the observer at the central line
counts the number lights along the runway on his left hand side visible to him and the
observer at ROP facing the runway counts the number of runway edge lights visible
to him on the other side of the runway, same row of lights as the other observer. This
experiment is to be done during poor visibility conditions when there is no air traffic
and the same has to be repeated in a variety of visibility conditions covering the
required reporting range and under different background conditions, like, day, twilight
and night and for various runway edge light intensities. Thus a conversion table for

29
various above conditions for actual RVR is originated from the number of runway
edge lights observed as shown in the sample table.
As the distance between two consecutive lighted lamps is normally 60 meter, the
columns 3 and 4 of the table are accordingly indicated. Similar tables are to be
prepared for all the various intensities of the runway edge lights normally in operation
under different visibility conditions. With these repeated experiments and calibration,
it will be possible to report RVR whenever required from the conversion tables by just
Station Airport No. of the Runway

Intensity of Runway Edge Background Condition: Day / Twilight /

Lights: Night
Serial No. of Lights Number of Lights Runway Visual
No. (1) Visible from ROP Visible From Central Range to be
(2) Line at Touchdown Reported
Point (3) (in Meters) (4)
1 1 2 120
2 2 3 180
3 3 4 240
4 4 5 300
5 5 6 360
6 6 7 420
counting the number of visible runway edge lights from ROP during poor visibility
conditions.
Method of Observation:
An observer having normal vision should go to the site either with a walkie-talkie set
or a telephone and establish communication with the current weather observer at the
ATC. At site, he should stand on the platform available and count the edge lights on
the other side of the runway. He should record the observations in a log book, check
again and confirm the observations taken and transmit the information to the control
tower. The following procedure may be followed:
(a) The observer to stand on the elevated platform
(b) Designate the nearest illuminated edge light opposite to him, on the other side of
the runway as No.1 of the count.
(c) Count the number of illuminated edge lights on the other side of the runway that
is just distinguishable.
(d) Note the number of lights counted in the log book.
(e) Check again and confirm the number of lights counted.
(f) Pass on the number of lights counted to the C.W. assistant at the tower by
telephone or walkie-talkie.
(g) The tower Assistant will read off from the RVR table, reportable RVR value
corresponding to the number of lights counted.

30
(h) The ATC Assistant will report the value so obtained according to the reporting
steps to be used.
(i) Observations may be taken and reported at desired interval and also whenever
there is a change in the reportable value and/or as often as the weather situation
warrants.
Since many a time, these observations have to be made in the night or early morning,
it is advisable to depute two persons to the “touchdown” site for taking manual RVR
observations. They will help each other in counting edge lights confirming the counts,
recording the observations and passing on the data to ATC. Also, this will provide
moral support so necessary in carrying out the difficult job satisfactorily.
Errors with Human Observer Systems:
Ideally, the RVR reported should correspond to the conditions on the runway
experienced by the pilot when landing or taking off. However, errors in the visual
observations occur due to a number of factors:
(a) Differences in the exposure to lights. Significant differences may occur in the
background luminance and extraneous lights to which an observer and a pilot are
exposed. This can be important where observations are not made at the runway
centre line (e.g. using a separate row of lights in a direction different from that of
the runway in use)
(b) Variations in vision among observers. Pilots must check their eyesight
periodically and have generally high demands on their vision, but this does not
necessarily apply to personnel making RVR assessments. A group of observers
may have a different distant visual acuity, significant variations in the visual
threshold of illumination in different background luminance conditions or other
degraded vision characteristics.
(c) Exposure of an observer to high levels of illumination. If this happens just before
making visual observations using lights, as would be the case when an observer
leaves a lighted area to make night observations, it would degrade the observer’s
ability to see the lights, and the RVR values would be underestimated, which could
result in the unnecessary deviations of aircraft to alternative aerodromes. This
difficulty can be overcome by allowing several minutes for adjustment to
illumination conditions outside the station.
(d) Beaming of the runway edge lights. The runway edge lights are so directed that
the beam intensities have a high value at the runway centre line while the intensity
falls off rapidly towards the edges. Because runway lights are not observed at the
centre line, the intensities directed towards the observer are lower. If the
calibration of visual observations as is not undertaken carefully, errors in reported
RVR values will occur.
Averaging of RVR:
Where instrumented systems are used for the assessment of RVR, the averaging period
of RVR should be:
(a) 1 minute for local routine and special reports and for RVR displays in ATS units,
and

31
 (b) 10 minutes for METAR and SPECI, except that when the 10-minute period
immediately preceding the observation includes a marked discontinuity in runway
visual range values, only those values occurring after the discontinuity shall be
used for obtaining mean values. A marked discontinuity occurs when there is an
abrupt and sustained change in runway visual range, lasting at least 2 minutes,
which reaches or passes through the values included in criteria for the issuance of
SPECI reports.
RVR Tendency:
In METAR and SPECI when instrumented systems are used for the assessment of
runway visual range, the variations in runway visual range during the 10-minute
period immediately preceding the observation shall be indicated as follows:
If the runway visual range values during the 10-minute period have shown a distinct
tendency, such that the mean during the first 5 minutes varies by 100 m or more from
the mean during the second 5 minutes of the period, this shall be indicated.
When the variation of the runway visual range values shows an upward or downward
tendency this shall be indicated by the abbreviation “U” or “D” respectively.
In circumstances when actual fluctuations during the 10-minute period indicate no
distinct tendency this shall be reported using the abbreviation “N”.
When indications of tendency are not available, no abbreviations shall be included.
2.3.5 Present Weather

Qualifier Weather Phenomenon

Intensity Descriptor Precipitation Obscuration Other

or
Proximity
MI Shallow DZ Drizzle BR Mist PO
BC Patches RA Rain FG Fog Dust/Sand
Light PR Partial SN Snow Whirls
(Covering Part of (dust
SG Snow FU Smoke
the Aerodrome) devils)
Grain VA
SQ Squalls
IC Ice Volcanic
DR Low Drifting Crystals FC Funnel
Moderate Ash
(Diamond Clouds
BL Blowing DU
dust) (Tornado
SH Showers Wide-Spread or Water
PL Ice dust Spout)
Pellets
TS Thunderstorm SA Sand SS Sand
GR Hail
+ Heavy FZ Freezing HZ Haze Storm
(Super Cooled) GS Small
DS Dust
Hail and/or
Storm
Snow Pellets

32
Example:
Having decided there is a weather phenomenon to be reported, the present weather is
encoded by considering each column in the table above.
For example:
There is rain - RA
It is heavy - +
It is a shower - SH
The encode becomes +SHRA
Explanations:
One or more groups w´w´, but not more than three, should be used to report all present
weather phenomena observed at or near the aerodrome and of significance to
aeronautical operations in accordance with the above Code table.
Appropriate intensity indicators and letter abbreviations should be combined in groups
of two to nine characters to indicate present weather phenomena.
The w´w´ groups shall be reported in the following order:
1. First, if appropriate, the qualifier for intensity or for proximity, followed without
a space by;
2. If appropriate, the abbreviation for the descriptor followed without a space by;
3. The abbreviation for the observed weather phenomenon or combinations thereof.
Intensity description:
 Intensity should be indicated only with precipitation, precipitation associated with
showers and/or thunderstorms, dust storm or sandstorm.
 If the intensity of the phenomena reported in the group is either light or heavy, this
shall be indicated by the appropriate sign.
 No indicator shall be included in the group when the intensity of the reported
phenomenon is moderate.
The following may be referred to:
Local Routine METAR and SPECI
Local Special Reports
Light FBL -
Moderate MOD ( no indication)
Heavy HVY +

The intensity of present weather phenomena reported in the group w´w´ shall be
determined by the intensity at the time of observation.

33
Qualifiers:
 If more than one significant weather phenomenon is observed, separate w´w´
groups should be included in the report in accordance with the Code table.
 If more than one form of precipitation is observed, the appropriate letter
abbreviations should be combined in a single group with the dominant type of
precipitation being reported first.
 In such a single group, the intensity should refer to the total precipitation and be
reported with one or no indicator as appropriate.
The qualifier SH:
 Should be used to indicate precipitation of the shower type.
 When associated with the indicator VC, the type and intensity of precipitation
should not be specified.
The qualifier TS:
 Should be used whenever thunder is heard or lightning is detected at the aerodrome
within the 10-minute period preceding the time of observation.
 When appropriate, TS should be followed immediately, without a space, by
relevant letter abbreviations to indicate any precipitation observed.
 The letter abbreviation TS on its own should be used when thunder is heard or
lightning detected at the aerodrome but no precipitation observed.
 A thunderstorm should be regarded as being at the aerodrome from the time thunder
is first heard, whether or not lightning is seen or precipitation is observed at the
aerodrome.
 A thunderstorm should be regarded as having ceased or being no longer at the
aerodrome at the time thunder is last heard, and the cessation is confirmed if
thunder is not heard for 10 minutes after this time.
The qualifier FZ:
 Should be used only to indicate supercooled water droplets or supercooled
precipitation and is used only with FG, DZ and RA.
 Any fog consisting predominantly of water droplets at temperatures below 0°C
should be reported as freezing fog (FZFG) whether it is depositing rime ice or not.
 Whether or not the supercooled precipitation is of the shower type need not be
specified.
The qualifier VC:
 Should be used to indicate the significant weather phenomena TS, DS, SS, FG,
FC, SH, PO, BLDU, BLSA, BLSN and VA observed in the vicinity of the
aerodrome.
 Vicinity means “Not at the aerodrome but not further away than approximately 8
km from the aerodrome perimeter and used only in METAR and SPECI.

34
 Phenomena:
 GR is used to report hail only when the diameter of the largest hailstones observed
is 5 mm or more.
 GS should be used to report small hail (diameter of the hailstones less than 5 mm)
and/or snow pellets.
 IC should be used to indicate the phenomenon ice crystals (diamond dust). For
w´w´ = IC to be reported, the visibility should be reduced by this phenomenon to
5000 metres or less.
 The abbreviations FU, HZ, DU and SA (except DRSA) should be used only when
the obstruction to vision consists predominantly of litho-meteors and the visibility
is reduced by the reported phenomenon to 5000 metres or less.
 The abbreviation BR should be used when the obstruction to vision consists of
water droplets or ice crystals. For w´w´= BR to be reported, the visibility reported
in the group VVVV should be at least 1000 metres but not more than 5000 metres.
 The letter abbreviation FG should be used when the obstruction to vision consists
of water droplets or ice crystals (fog or ice fog). For w´w´= FG to be reported
without the qualifiers MI, BC or VC, the visibility reported in the group VVVV
should be less than 1000 metres.
 For w´w´= MIFG to be reported, the visibility at two metres above ground level
should be 1 000 metres or more and the apparent visibility in the fog layer shall be
less than 1000 metres.
 The abbreviation VCFG can be used to report any type of fog observed in the
vicinity of the aerodrome.
 The abbreviation BCFG is used to report fog patches. BCFG should be used only
when the visibility in parts of the aerodrome is 1000 metres or more although,
when the fog is close to the observing point, the minimum visibility reported will
be less than 1000 metres.
 The abbreviation PRFG is used to report fog covering part of the aerodrome. The
apparent visibility in the fog patch or bank should be less than 1000 metres, and
the fog should be extending to at least two metres above ground level.
 BL (blowing) is used to report DU, SA or SN raised by the wind to a height of 2m
or more above the ground.
 DR (Low drifting) is used with DU, SA, or SN raised by the wind to less than 2m
above ground level.
 SQ is used to report squalls when a sudden increase of at least 16 knots in wind
speed is observed, the speed rising to 22 knots or more and lasting for at least one
minute.
2.3.6 Cloud or Vertical Visibility
Code form: NsNsNshshshs or VVhshshs or SKC or NSC
Reporting:

35
Cloud groups consist of six characters under normal circumstances. The first three
indicate cloud amount with:
1/8 to 2/8 reported as FEW (Few)
3/8 to 4/8 reported as SCT (Scattered)
5/8 to 7/8 reported as BKN (Broken) and
8/8 reported as OVC (Overcast)
The last three characters indicate the height of the base of the cloud in units of 30 m
or 100 ft upto 3000 m (10000 ft).
Example: 3/8 of Stratocumulus with a base of 1850 will be encoded: SCT018.
Cloud Type:
 Types of cloud other than significant convective clouds are not identified.
 Significant convective clouds are; Cumulonimbus indicated by CB and Cumulus
congestus of great vertical extent indicated by TCU.
 The contraction TCU, taken from “Towering Cumulus”, is an ICAO abbreviation
used to describe this type of cloud.
Repeated Cloud Groups:
The cloud group can be repeated to report different layers or masses of cloud but the
number of groups should not normally exceed three.
The following criteria should be followed for reporting cloud layers:
 The lowest individual layer (mass) of any amount as FEW, SCT, BKN or OVC.
 The next individual layer of more than 2/8 as SCT, BKN, or OVC as appropriate.
 The next higher layer of more than 4/8 as BKN or OVC; and
 Cumulonimbus (CB) and/or towering cumulus clouds (TCU), whenever observed
and not already reported.
Example:
There are 1/8 at 500 ft
2/8 Cumulonimbus at 1000 ft
3/8 Cumulus at 1800 ft
5/8 Stratocumulus at 2500 ft
At mountain stations, when cloud base is below station level, the cloud group should
read NsNsNs///.
Example: SCT///, FEW///CB
The reported cloud would be:
FEW005 FEW010CB SCT018 BKN025

36
 Explanations:
1. The cloud groups are reported in ascending order of height.
2. When there are no clouds of operational significance and no restriction on vertical
visibility and the abbreviation CAVOK is not appropriate, the abbreviation NSC
(Nil Significant Cloud) should be used. (Cloud of operational significance: A
cloud with the height of cloud base below 1500 m (5000 ft) or below the highest
minimum sector altitude whichever is greater, or a cumulonimbus cloud or a
towering cumulus cloud at any height).
3. When Cumulonimbus (CB) and Towering Cumulus (TCU) have a common cloud
base, the type of cloud is reported as CB and the amount of clouds is encoded as
the sum of CB and TCU amounts at that cloud base.
Vertical Visibility:
When the sky is obscured and cloud details cannot be assessed but information on
vertical visibility is available, the cloud group should be replaced by a five character
group, the first two characters being VV followed by the vertical visibility in units of
30 m or 100 ft as for cloud base. When the sky is obscured but the vertical visibility
cannot be assessed the group will read VV///.
Example: VV003 (Vertical visibility three hundred feet/ 90 meters)
2.3.7 Air and Dew Point Temperature
Code format: T´T´/ TdTd
The observed air temperature and dew point temperature, each as two figures rounded
to the nearest whole degree Celsius, should be reported next.
Temperatures below 0 degrees Celsius will be preceded by M to indicate minus.
Example: Minus 9.5 degrees Celsius is reported as M09.
Explanations: Air temperature and dew point values of 0.5 degrees will be rounded
up to the higher whole degree.
Example: Air temperature of 9.5 degree Celsius and Dew point temperature of 3.3
degree Celsius will be reported as 10/03
Alternative to recording temperature when automated instrument is out of
order: Psychrometer / Sling Psychrometer:
An instrument used for measuring the water-vapor content of the air. It consists of two
ordinary glass thermometers. The bulb of one thermometer (wet-bulb) is covered with
a clean muslin wick, which is saturated with water prior to an observation. When the
bulbs are properly ventilated, they indicate the wet- and dry-bulb temperatures of the
atmosphere.
Use Hygrometric Tables to find out Dew Point temperature from Dry and Wet Bulb
Temperatures
2.3.8 Pressure – QNH
Code Format: QPHPHPHPH

37
 The last group of the main part of the report should indicate the QNH rounded down
to the nearest whole HectoPascal.
The group starts with the letter Q followed by four figures.
In local reports, QFE also is to be reported.
Example: A QNH of 995.6 hPa is reported as Q0995
Alternative method to record QNH and QFE when automated instruments are
out of order:
 Use either of available Digital Barometer/Aneroid barometer installed at the
station.
 Take values from the Surface observatory of the station/nearby station and apply
correction, if any, known.
 Use Portable Airport Met Instruments Kit provided.
2.3.9 Supplementary Information
Code Format: WS RWYDRDR Or RE wiwi WS ALL RWY (WTsTs/SSi)
(RRRRERCReReRBRBR)
For international dissemination this section is used for reporting:
 Recent weather phenomena of operational significance;
 Information on wind shear in the lower layers; and,
 Other information in accordance with regional air navigation agreement including:
(a) Sea surface temperature and the state of the sea, and
(b) State of the runway
The other information group is not being used in India.
Observations made at aerodromes should include the available supplementary
information concerning significant meteorological conditions, particularly those
in the approach and climb-out areas, and specifically the location of
cumulonimbus or thunderstorm, moderate or severe turbulence, wind shear, hail,
severe line squall, moderate or severe icing, freezing precipitation, marked mountain
waves, sandstorm, dust-storm, blowing snow or funnel cloud (tornado or waterspout).
Where practicable, the information should identify the vertical extent and direction
and rate of movement of the phenomenon. As turbulence, wind shear and icing cannot,
for the time being, be satisfactorily observed from the ground, evidence of their
existence should be derived from aircraft observations during the climb out or
approach phases of flight to be made in accordance with separate regulations.
In local routine and special reports and in METAR
and SPECI, the following recent weather
phenomena, i.e. weather phenomena observed at the REFZDZ, REFZRA
aerodrome during the period since last hour,
whichever is the shorter, but not at the time of
observation, should be reported, up to a maximum

38
three groups, in the supplementary information:
freezing precipitation
Moderate or heavy precipitation (including showers REDZ, RERA, RESN, RESG,
thereof) REPL, RESHRA, RESHSN,
RESHGR, RESHGS
Blowing snow REBLSN
Dust-storm or Sandstorm RESS, REDS
Thunderstorm RETS
Funnel Cloud (tornado or water spout) REFC
Volcanic Ash REVA

In local routine and special reports, the following significant meteorological

conditions, or combination thereof, should be reported in supplementary information

Cumulonimbus cloud CB
Thunderstorm TS
Moderate or severe turbulence MOD TURB, SEV TURB
Wind Shear WS
Hail GR
Severe line squall SEV SQL
Moderate or severe icing MOD ICE, SEV ICE
Freezing precipitation FZDZ, FZRA
Severe mountain wave SEV MTW
Duststorm, Sandstorm SS, DS
Blowing snow BLSN
Funnel cloud (tornado or water FC
spout)

Information on recent weather of operational significance observed at the aerodrome

within the period since the last issued routine report or last hour, whichever is the
shorter, but not at the time of observation should be reported.
 Where local circumstances warrant, information on wind shear should be added in
reports disseminated beyond the aerodrome.
 Information on wind shear should be added in the form “WS RWY 12” or “WS
ALL RWY”.
 Information on recent significant weather should be added in the form
“REFZRA”.
 Significant directional variations in visibility particularly, those affecting the
approach area, should be observed and reported.
 Directional variations in visibility should be reported with an indication of the
direction of observation, for example, “VIS 2000M TO S”.

39
  RVR values above 1500 m and up to 2000 m are to be reported in METAR/SPECI
and in special MET REPORTS as supplementary information which should not
be disseminated internationally.
 If the horizontal visibility is 1500 m or less but RVR is more than 2000 m the same
should be reported as “RVR ABV 2000 M” as supplementary information.
2.4 CRITERIA FOR ISSUANCE OF LOCAL SPECIAL REPORTS AND SPECI
Local special report and SPECI should be issued whenever changes in accordance
with the following criteria occur:
2.4.1 Surface Wind
1. When the mean surface wind direction has changed by 600m or more from that
given in the latest report, the mean wind speed before and/or after the change being
10 knots or more;
2. When the mean surface wind speed has changed by 10 knots or more from that
given in the latest report;
3. When the variation from the mean surface wind speed (gusts) has increased by 10
knots or more from that given in the latest report, the mean speed before and/or
after the change being 15 knots or more.
2.4.2 Visibility
When the visibility is improving and changes to or passes through one or more of the
following values, or when the visibility is deteriorating and passes through one or
more of the following values:
800, 1500, 3000 or 5000 meters.
2.4.3 Runway Visual Range (RVR)
When the runway visual range is improving and changes to or passes through one or
more of the following values, or when the runway visual range is deteriorating and
passes through one or more of the following values:
150, 350, 600 or 800 metres.
2.4.4 Present Weather
1. When the onset, cessation or change in intensity of any of the following weather
phenomena occurs:
a. Freezing precipitation
b. Moderate or heavy precipitation (including showers thereof)
c. Thunderstorm (with precipitation)
d. Duststorm
e. Sandstorm
f. Funnel cloud (tornado or waterspout)
2. When the onset or cessation of any of the following weather phenomena occurs:

40
 a. Ice crystals
b. Freezing fog
c. Low drifting dust, sand or snow
d. Blowing dust, sand or snow
e. Thunderstorm (without precipitation)
f. Squall
2.4.5 Cloud
When the height of base of the lowest cloud layer of BKN or OVC extent is lifting
and changes to or passes through one or more of the following values, or when the
height of base of the lowest cloud layer of BKN or OVC extent is lowering and passes
through one or more of the following values:
30, 60, 150, 300, or 450 m (100, 200, 500, 1000 or 1500 ft.)
When the amount of a cloud layer below 450 m (1500 ft) changes:
1. From SCT or less to BKN or OVC; or
2. From BKN or OVC to SCT or less.
2.4.6 Vertical Visibility
When the sky is obscured and the vertical visibility is improving and changes to or
passes through one or more of the following values, or when the vertical visibility is
deteriorating and passes through one or more of the following values:
30, 60, 150 or 300 m (100, 200, 300, 1000 ft)
2.4.7 Air temperature
When air temperature has increased by 20 C or more from that given in the latest
report.
2.5 DISSEMINATION OF SPECI AND SPECIAL REPORTS
1. When a deterioration of one weather element is accompanied by an improvement
in another element, a single SPECI / local special report should be issued. It should
be treated as a deterioration report.
2. SPECI representing a deterioration in conditions shall be disseminated
immediately after the observation.
3. A SPECI representing a deterioration of one weather element and an improvement
in another element shall be disseminated immediately after the observation.
4. A SPECI representing an improvement in conditions shall be disseminated only
after the improvement has been maintained for 10 minutes; it shall be amended
before dissemination, if necessary, to indicate the conditions prevailing at the end
of that 10 minute period.

41
 5. Local Special Reports shall be transmitted to local air traffic services units as soon
as the specified conditions occur, even if it represents an improvement in
conditions.
6. Local Special Reports shall also be made available to the operators and to other
users at the aerodrome.
# Refer Aviation Circular 2/2015 regarding SPECI dissemination
2.6 ADDITIONAL REPORTS
This message is identified with the prefix “ADDITIONAL” and supplied on red
colored paper. However, these are not disseminated outside the aerodrome of origin.
These are issued to local ATC units in addition to the local routine reports and local
special reports.
ADDITIONAL reports shall be issued for changes in cloud base height and visibility
by all aeronautical meteorological offices in India as per the following criteria:

Element Criteria Issued by

Cloud base Whenever the height of base of cloud covering All stations equipped with
more than half the sky changes to or passes 90 ceilometers/ ceilographs.
or 120 metres (300 or 400 feet)
Visibility Whenever visibility changes to or passes 2000 By all aerodrome meteorological
or 4000 metres. offices/ aeronautical
meteorological stations recording
routine observations.

2.7 TREND FORECAST

2.7.1 General:
1. Landing forecasts issued in India as a routine are called trend forecast.
2. These forecasts are intended to meet the requirements of local users and of aircraft
within about one hour’s flying time from the aerodrome.
3. All Aerodrome Meteorological Offices (with forecasting facility) issue TREND
forecasts during the forecast watch hours.
4. The AMSs at Kochi and Kozhikode also issue TREND forecasts.
5. They are appended to a local routine or local special report, or a METAR or
SPECI.
6. The period of validity of a trend forecast shall be 2 hours from the time of the
report, which forms part of the landing forecast.
2.7.2 Inclusion of meteorological elements in trend forecasts:
1. The trend forecast indicates significant changes in respect of one or more of the
elements: surface wind, visibility, weather and clouds.
2. Only those elements are included for which a significant change is expected.

42
 3. However, in the case of significant changes in respect of cloud, all cloud groups,
including layers, or masses not expected to change, shall be indicated.
4. In the case of a significant change in visibility, the phenomenon causing the
reduction of visibility should also be indicated.
5. When no change is expected to occur, this shall be indicated by the term “NOSIG”.
2.7.3 Use of change indicators:
When a change is expected to occur, the trend forecast message should begin with one
of the change indicators “BECMG” or “TEMPO”.
BECMG
 The change indicator “BECMG” is used to describe forecast changes where the
meteorological conditions are expected to reach or pass through specified values
at a regular or irregular rate.
 The period during which, or the time at which, the change is forecast to occur is
indicated, using the abbreviations “FM”, “TL”, or “AT”, as appropriate.
 They should be followed by a time group in hours and minutes.
 When the change is forecast to begin and end wholly within the trend forecast
period, the beginning and end of the change shall be indicated by using the
abbreviations “FM” and “TL” respectively with their associated time groups.
For example, for a trend forecast period from 1000 to 1200 UTC in the form,
“BECMG FM1030 TL1130” (in both METAR and local routine report).
TEMPO
 The change indicator “TEMPO” is used to describe forecast temporary
fluctuations in the meteorological conditions which reach or pass specified values
and last for a period of less than one hour in each instance and, in the aggregate,
cover less than one-half of the period during which the fluctuations are forecast to
occur.
 The period during which the temporary fluctuations are forecast to occur shall be
indicated, using the abbreviations “FM” and/or “TL”, as appropriate
 They should be followed by a time group in hours and minutes.
Example, for a trend forecast period from 1000 to 1200 UTC in the form “TEMPO
FM1030 TL1130” (in both METAR and local routine report).
Surface wind
The trend forecast for surface wind is issued for the following conditions:
1. A change in the mean wind direction of 600 or more, the mean speed before and/or
after the change being 10 kts or more;
2. A change in mean wind speed of 10 kts or more.
Example:

43
An expected temporary fluctuation of surface wind from 250° at 35 kt with maximum
speed (gusts) to 50 kt throughout the period of the trend forecast is indicated in the
form:
“TEMPO 25035G50KT” in METAR and
“TEMPO 250/35KT MAX50” in METREPORT
Visibility
1. Trend forecast for visibility is issued when it is expected to change to or pass
through any one of the values 150, 350, 600, 800, 1500, 3000 or 5000 m.
2. Whenever reduction of visibility is indicated in trend forecasts in locally
disseminated reports, the reasons for such reduction in visibility is also specified
in the trend part of the message.
Example:
A temporary reduction throughout the period of the trend forecast of the visibility to
750 m in fog shall be rounded down to 700 m and indicated in the form
“TEMPO 0700” in METAR or
“TEMPO VIS 700M” MET REPORT.
Weather phenomena
1. The trend forecast should indicate the expected onset, cessation or change in
intensity of one or more of the following weather phenomena or combinations
thereof:
a. Freezing precipitation
b. Moderate or heavy precipitation (including showers thereof)
c. Thunderstorm (with precipitation)
d. Duststorm
e. Sandstorm
f. Other weather phenomena if they are expected to cause a significant change in
visibility.
2. The trend forecast should indicate the expected onset or cessation of one or more
of the following weather phenomena or combinations thereof:
a. Ice crystals
b. Freezing fog
c. Low drifting dust, sand or snow
d. Blowing dust, sand or snow
e. Thunderstorm (without precipitation)
f. Squall
g. Funnel cloud (tornado or waterspout)

44
3. The total number of phenomena reported in (a) and (b) should not exceed three.
4. The expected end of the weather phenomena shall be indicated by the abbreviation
“NSW”.
Example:
“TEMPO FM0300 TL0430 TSRA” (METAR) and “TEMPO FM0300 TL0430 MOD
TSRA” (local routine report).
An expected cessation at 1630 UTC, of significant weather, such as a thunderstorm,
is indicated in the form “BECMG AT1630 NSW” (in both METAR and local routine
report).
Clouds
1. Trend forecast should be issued when the height of the base of a cloud layer of
BKN or OVC extent is expected to change to or pass through one or more of the
following values: 30, 60, 150, 300 and 450 m (100, 200, 500, 1000 and 1500 ft).
2. When the height of the base of a cloud layer is below or is expected to fall below
or rise above 450 m (1500 ft), the trend forecast should also indicate changes in
cloud amount from FEW, or SCT increasing to BKN or OVC, or changes from
BKN or OVC decreasing to FEW, or SCT.
3. When no clouds of operational significance are forecast and “CAVOK” is not
appropriate, the abbreviation “NSC” should be used.
Vertical visibility
When the sky is expected to remain or become obscured and vertical visibility
observations are available at the aerodrome, and the vertical visibility is forecast to
change to or pass through one or more of the following values: 30, 60, 150, or 300m
(100, 200, 500, or1000 ft), the trend forecast should indicate the change.

45
 Chapter - 3
CLIMATOLOGY

3.1 GENERAL PROVISIONS

Aeronautical climatological information required for the planning of flight operations
shall be prepared in the form of aerodrome climatological tables and aerodrome
climatological summaries. Such information shall be supplied to aeronautical users as
agreed between the meteorological authority and those users.
Aeronautical climatological information shall normally be based on observations
made over a period of at least five years and the period shall be indicated in the
information supplied.
Climatological data related to sites for new aerodromes and to additional runways at
existing aerodromes shall be collected starting as early as possible before the
commissioning of those aerodromes or runways.
3.2 AERODROME CLIMATOLOGICAL TABLES
Arrangements shall be made for collecting and retaining the necessary observational
data and shall:
 Prepare aerodrome climatological tables for each regular and alternate
international aerodrome; and
 Make available such climatological tables to an aeronautical user within a time
period as agreed between the meteorological authority and that user.
3.3 AERODROME CLIMATOLOGICAL SUMMARIES
Aerodrome climatological summaries shall follow the procedures prescribed by the
World Meteorological Organisation. The summaries shall be prepared using the model
specified by the World Meteorological Organisation, and shall be published and kept
up to date as necessary.
3.4 COPIES OF METEOROLOGICAL OBSERVATIONAL DATA
IMD, on request and to the extent practicable, shall make available to any other
meteorological authority, to operators and to others concerned with the application of
meteorology to international air navigation, meteorological observational data
required for research, investigation or operational analysis.
3.5 PROCESSING OF AERONAUTICAL CLIMATOLOGICAL INFORMATION
Meteorological observations for regular and alternate aerodromes shall be collected,
processed and stored in a form suitable for the preparation of aerodrome
climatological information.
3.6 EXCHANGE OF AERONAUTICAL CLIMATOLOGICAL INFORMATION
Aeronautical climatological information shall be exchanged on request between
meteorological authorities. Operators and other aeronautical users desiring such
information shall apply to the meteorological authority responsible for its preparation.

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 3.7 CONTENT OF AERONAUTICAL CLIMATOLOGICAL INFORMATION
3.7.1 Aerodrome Climatological Table
An aerodrome climatological table shall give:
 Mean values and variations there from, including maximum and minimum values,
of meteorological elements (for example, of air temperature); and /or
 The frequency of occurrence of present weather phenomenon affecting flight
operations at the aerodrome (for example, of sandstorms); and/or
 The frequency of occurrence of specified values of one, or of a combination of
two or more, elements (for example, of a combination of low visibility and low
cloud).
 Aerodrome climatological tables shall include the information required for the
preparation of aerodrome climatological summaries.
3.7.2 Aerodrome climatological summaries
Aerodrome climatological summaries shall cover:
 Frequencies of occurrence of runway visual range/ visibility and/ or height of the
base of the lowest cloud layer of BKN or OVC extent below specified values at
specified times;
 Frequencies of visibility below specified values at specified times;
 Frequencies of height of base of the lowest cloud layer of BKN or OVC extent
below specified values at specified times;
 Frequencies of occurrence of concurrent wind direction and speed within specified
ranges;
 Frequencies of surface temperature in specified ranges of 5oC at specified times;
and
 Mean values and variations there from, including maximum and minimum values
of meteorological elements required for operational planning purposes, including
take-off performance calculations.

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 Chapter - 4
AVIATION WEATHER FORECAST

4.1 INTRODUCTION
Definition: A weather forecast is a statement of expected meteorological conditions for a
specified time or period, and for a specified area or portion of airspace (ICAO Annex 3 -
Meteorology).
Meteorological Watch Office (MWO)/Airport Meteorological Office (AMO) delivers
consistent & timely weather forecast & related information for the aviation activities of the
country through a team of highly skilled people to enhance safe and efficient flight
operations.
Applicability: The forecasting procedures outlined in this SOP are applicable to all aviation
weather forecasting offices of the country. However each forecasting office will develop
the forecast based on details - regarding available data sources, evaluation of the weather
data, & specific feature of the aerodrome (local topography), experience of the forecaster
etc.
Wording: The terms are used in this SOP to specify the degree of obligation with reference
to stated procedures.
1. Weather forecast/ forecast describes: Aviation weather forecast.
2. Shall - The procedure is mandatory
3. Should - The procedures is recommended
4. May - The procedure is optional
5. Will - Means futurity, and never indicates any degree of requirement for application
of a procedure.
Basis of Weather Forecasting: The data gathered from various observational sources,
synoptic charts & model out puts form the basis of all weather forecasts, advisories,
warnings and briefings.
Observations:
 Surface Aviation Weather Observations (Current Weather)
 Upper Air Observations (RS/RW& PB)
 Remote sensing (Radar, Satellite etc.)
 Lightning Data
 Aircraft Meteorological Data Relay (AMDAR)

48
 Synoptic Charts:
 Surface Level Analysis
 Upper Level Analysis.
NWP model: Particularly Mesoscale models (including local models) for analyses and
prognoses.
Types of aviation weather forecast: There are different types of aviation forecasts
designed to meet requirements for the various stages of flight planning. They differ in
respect of area or airspace covered and period of validity. Forecast may be categorized as
1. Terminal aerodrome forecast (TAF)
2. Route forecast
3. Local / Area forecast
4. Trend forecast
4.2 TERMINAL AERODROME FORECAST (TAF)
4.2.1 Basis of TAF
Definition: Terminal Aerodrome Forecast (TAF) is a concise statement of the expected
meteorological conditions within 8 km radius from the centre of an airport's runway during
a specified period (usually 24 hours).
Observational requirements of TAF:
TAF are issued for aerodromes for which regular half hourly and special weather reports
meeting standards for observations are available.
Note: If an aerodrome is closed for greater than 24 hours, no TAF needs to be generated.
The next TAF shall be generated based on at least two consecutive hourly observations with
all required elements (wind, visibility, weather and, sky condition, temperature, dew point,
and altimeter) immediately prior to the issue time of the TAF & reopening of the station.
However, requirement of TAF by ATC authority shall be given highest priority in closed
condition also.
4.2.2 Updation of TAF
Time References & Time of updation/transmission:
All times in the TAF shall be are stated in Coordinated Universal Time (UTC) or Zulu time
with whole hour time increments.
To facilitate flight planning, aerodrome forecasts shall be transmitted on OLBS not later
than 20 minutes prior to the beginning of their period of validity.
4.2.3 Issuing authority & dissemination of TAF
In India, TAF is being issued by all AMO/MWO for their own aerodromes and also for
their associated AMS as per requirement.
49
 Note: If any AMO is having restricted watch/operational hour the AMO/MWO of
respective states/region will assume the responsibility of issue of TAF for the close period
of the said (parent) AMO.
TAF and amended TAF shall be issued only in accordance with the template.
TAF are provided through web based automated information dissemination system known
as On-line Briefing System (OLBS) of IMD and can be found on two websites after log in
namely https://olbs.amsschennai.gov.in/ and https://olbs.amssdelhi.gov.in
4.2.3 Types & validity of TAF
TAF may be categorized as short & long.
Short TAF are issued with 9 hours validity period for the requirement of domestic flight,
VOLMET and DVOLMET broadcast. Short TAF are transmitted locally & nationally only.
Long TAF are issued with 30 hours validity for the use of international flight & transmitted
through international mode.
Note: When issuing TAF, meteorological offices shall ensure that only one TAF of a
particular type (Short/Long) is valid at an aerodrome at any given time & when a new TAF
is issued, it automatically cancels the previous one.
4.2.4 Work sheet for preparation of TAF
Producing an accurate TAF is challenging for numerous reasons. Therefore it is suggested
to prepare & complete some type of worksheet prior to development & dissemination of a
TAF.
Worksheets are nothing more than a list of charts, bulletins, and different products that
provide a standardized and systematic approach to TAF preparation and the forecaster
indicates he has studied by placing a check mark next to each item.
A good TAF worksheet should follow the "funnel" forecast thought process of looking at
hemispheric features down to local features considering atmospheric scales as 10 percent
hemispheric, 30 percent synoptic, 60 percent mesoscale and local scale and lead the
forecaster to some definite conclusion about what weather conditions to forecast.
A simple guide line worksheet is described below for this purpose.
Terminal Aerodrome Forecast (TAF) Tools/Worksheet
Analysis:
HEMISPHERIC Feature:
 Mark long wave features affecting your station i.e. Ridge/Trough, Axis location: West/
East/ Overhead.
 Analyse long wave ridge/trough amplitude changes and axis shift during 24/30 hour
forecast period.
SYNOPTIC Feature:

50
 Examine/ Consult Synoptic forecast bulletins issued by NWFC/SWFC
 Examine & analyse following input data (charts) & interpolation as necessary to
describe upper air and surface features that will influence your forecast period at 6
hours interval (00 HR, 06 HR, 12 HR, and 18 HR).
 Examine 200 mb to delineate - Jet Maxima (Y/N) & Cold/Warm region/area.
 300 mb to identify - Confluence/Difluence region/area
 500 mb to examine - Trough / Ridge position, CAA/WAA, vorticity advection, character
of airmass (moist/dry), Contour height rise/fall
 700 mb to examine - Trough/Ridge position, CAA/WAA, airmass (Moist/dry)
 Lower level (850 & 925 mb) to examine - Dryline, Trough/Ridge position, CAA/WAA,
airmass character (Moist/dry), Low-Level Jet (Y/N)
 Surface level to delineate - High/low pressure zone, temperature & moisture gradient,
CAA/WAA & moisture advection etc.
Vertical profile:
 Tephigram analysis (00Z/12Z) applicable to today’s forecast problem.
 Examine the stability index value i.e. LI, TT, SWEAT, KI, CAPE, CIN etc.
 Examine CCL/LCL & FZL value, convective temperature etc.
Note: Explain which values are pertinent today & why
Models (Output & Guidance):
1. Examine various model outputs & diagnostic products available at IMD & other related
website.
2. Make value addition to model output for framing the final forecast based on –
 Station specific current weather observation.
 Station specific prevailing wind flow pattern.
 Consistency of model output compared to previous run.
 Latest Radar signature - animations for reflectivity and velocity.
 Satellite imagery to include special enhancements for fog, ground temperature,
severe weather, movement of features, etc.
 Lightning data.
Climatology:
Examine whether final forecast of the station make sense based on monthly/daily
aerodrome climate summary data? (Extreme temperatures, 24-hour precipitation extremes
- (Y/N)?
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 Station Consideration:
 Microscale (point) forecasting like TAF, requires the forecaster to consider and give
more attention to station factors than synoptic condition.
 The topography of an area can significantly modify any synoptic feature.
 Aviation Forecasters should have a thorough knowledge on local-area
topography/geography and all associated local effects of any forecasted station.
 Above all the forecaster’s experience plays a vital role for accurate TAF.
Note: Obviously, it is impossible to design a universal TAF worksheet that can be used by
every weather forecasting office. But, there are many elements common to a sound
worksheet. However TAF specific to each airfield will be issued based on available &
evaluation/analysis of the weather data, local features besides forecaster’s experience.
4.2.5 TAF Formulation
When formatting a TAF every effort shall be made to present a representative outlook of
the forecast elements for the valid period as possible.
On the other hand, the forecaster should avoid redundancy, ambiguity and the inclusion of
additional groups that illustrate changes but have no operational impact on flight
operations.
Aerodrome forecast and amendments thereto should be issued only in accordance
with the template and shall be disseminated in the TAF code form.
4.2.6 Encoding the Elements in TAF
The initial line for the TAF shall contain all the required elements describing the prevailing
conditions forecasted to occur at the beginning of the forecast period.
This conditions prevail until the end of the forecast period or until modified by a change
group/line like –
BECMG, FM, TEMPO, and PROB.
4.2.7 TAF Template
Kindly Refer to Appendix-IV.
4.2.8 Description of TAF Template
Template consists of broad 5 parts (group) & are issued in the following order as
indicated:
[Type of forecast] [ICAO Station Identifier] [Date and Time of Origin] [Valid Period Date
and Time] [Forecast Meteorological Conditions]
Type of forecast:
(Inclusion criteria M = inclusion mandatory, part of every message)

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 There are two types of TAF issuances (Forecast) a routine forecast (TAF) and an
amended forecast (TAF AMD)
 An amended TAF is issued when the current TAF no longer adequately describes the
on-going weather or the forecaster feels the TAF is not representative of the current or
expected weather.
 Amended TAFs are valid from the current hour to the ending hour of the original TAF.
 Corrected (COR) TAF included when the TAF is a correction of a previously issued
TAF; Example: TAF (TAF COR)/TAF AMD
ICAO Station location Identifier:
(Inclusion criteria, M= inclusion mandatory, part of every message)
The TAF code uses the ICAO four letter location identifier.
Example:
TAF VECC 110500Z 1106/1212 19008KT 3500 HZ SCT018 BKN100
TEMPO 1108/1112 2000 TSRA SCT015 FEW025CB OVC090
BECMG 1122/1124 2800 -RA HZ
BECMG 1203/1205 3500 -RA HZ
TEMPO 1205/1209 2000 TSRA SCT015 FEW025CB OVC090 =
VECC is the NSCBI (Dumdum, Kolkata) Airport’s ICAO four letter code.
Date & Time of origin:
(Inclusion criteria, M = inclusion mandatory, part of every message)
In the TAF, there are two items of date-time information. The first group indicates the
date and time at which the TAF issued.
Two-digit date with a four-digit time group (dd/hh/mm) appended with Z to denote the
time (UTC)
Example:
TAF VECC 110500Z
110500Z the digits 11 identify the day of the month. Other 4-digit and Z indicates hours
and minutes in UTC. The above TAF, originates on 11th day of the month, at 05:00,
UTC.
Valid Period Date and Time:
(Inclusion criteria, M = inclusion mandatory, part of every message)
The second time group with UTC valid period of the forecast consists of two four-digit
sets, separated by a "/". The first four-digit set is a two-digit date followed by the two-
digit beginning hour, and the second four-digit set is a two-digit date followed by the two-
digit ending hour.

53
In the case of an amended forecast, or a forecast which is corrected or delayed, the valid
period may be for less than 09/30 hours
Example:
TAF VECC 110500Z 1106/1212
The day of month is repeated, 11, and is followed by the start of the forecast time in
hours, 06, and then, separated by a slash the end of the forecast time, with the validation
day of the month, 12 and end of the validity period in hours, 12.
Forecast Meteorological Conditions:
Forecast Meteorological condition are included in the TAF as per following order as
indicated:
 Surface Wind
 Visibility
 Weather
 Cloud (sky condition) and
 If a significant change to one or more of these elements is expected during the period of
validity a new time period with the following change group is included : From as FM;
Becoming as BECMG; TEMPO; Probability as PROB 30/40
The following describes how the meteorological elements to be indicated in the above
Template:
Surface wind (Direction & Speed with unit): (Inclusion criteria, M = inclusion
mandatory, part of every message)
Surface Wind & Wind Gust: (Inclusion criteria, C = inclusion conditional, dependent on
meteorological conditions)
Wind group writing/inclusion - GENERAL procedure:
 Normally there will be a five-figure group (dddff) to indicate the ten-minute mean
wind followed by an abbreviation Knot (KT) without space to indicate the wind
speed units used.
 The first three figures indicate the wind direction and the last two the wind speed.
Example: TAF VECC 110500Z 1106/1212 19008KT
Wind comes from 190° with speed 08 KT.
 When it is not possible to forecast a prevailing particular direction, the forecast wind
direction is indicated as “variable” using “VRB” followed by an abbreviation Knot
(KT) without space (for example, during light wind conditions (less than 3kt) or
thunderstorms) Example :- VRB02KT

54
  Values of wind direction less than 100o shall be preceded by 0 and a wind from true
north shall be reported as 360. Values of wind speed less than 10 units shall be
preceded by 0.
 When the wind is forecast to be less than 1 knot (calm), it will be indicated as
00000KT.
 Wind gusts are noted by the letter "G" appended to the wind speed followed by the
highest expected gust and coded form is dddffGffKT. Example: 35012G20KT
(Wind three five zero at one two gust two zero)
 When the wind speed of 100KTs or more is forecast it shall be indicated to be more
than 99KT in the form P99KT. Example: 120P99KT
Surface wind writing/inclusion - SPECIAL procedure:
The change for surface wind is issued for the following conditions:
 A change in the mean wind direction of 60° or more, the mean speed before and/or
after the change being 10 KT or more.
 A change in mean wind speed of 10 KT or more.
Example: An expected fluctuation of surface wind from 250o at 05KT with speed to
15KT throughout the period after the fluctuation is indicated in the form: BECMG
25015 KT
Note: Squalls are not forecasted in the wind group; if expected, they shall be included
in the significant weather group (TEMPO) with direction and speed.
Surface Visibility: (Inclusion criteria, M = inclusion mandatory, part of every message)
 Visibility Group: VVVV
 Encode the forecasted prevailing visibility for the initial forecast period and in
any subsequent FM group or BECMG group that includes an expected change.
 Visibility is indicated in meters rounded down to the nearest reportable value.
 When the visibility is forecast to be
• less than 800 m it is expressed in steps of 50 m;
• between 800 m and 5 km, in steps of 100 m;
• between 5 km and 10 km in steps of km and
• More than 10 km, it is expressed as 10 km, except CAVOK condition.
 Include a weather group immediately following the visibility group whenever
forecasting a visibility of 5000 meters or less.
Example: TAF VECC 110500Z 1106/1212 19008KT 3500 HZ.
Visibility is 3500 metre due to haze.

55
Significant change in Visibility:
 In the case of a significant change in visibility, the phenomenon causing the reduction
of visibility should also be indicated and only one value of the following significant level
will be included.
 When the visibility is improving and changes to or passes through one or more of the
following values, or when the visibility is deteriorating and passes through one or more
of the following values: 150, 350, 600 800, 1500, 3000 or 5000 meters,
 Only one value of the significant level will be included in visibility group.
Note: For deteriorating condition use only one value between 1500 & 800. From 1500 next
value will be less than 800 but in improving condition both value can be included in
sequence.
If the visibility will alternate between significant values, describe the situation in a change
group. Do not use variable visibility remarks.
Weather: (Inclusion criteria, C = inclusion conditional, dependent on meteorological
conditions)
Weather Group: w´w´
General consideration: Encode the forecasted weather and obstructions to vision, if any,
for the initial forecast period and any subsequent FM or BECMG lines.
 If no significant weather is expected in the initial time period or additional FM lines,
omit the line.
 One or more groups (w´w´) up to a maximum of three of the following weather
phenomena or combinations thereof, together with their characteristics and, where
appropriate, their intensity:
Freezing precipitation/ Freezing Fog/ Moderate or heavy precipitation (including
showers thereof)/ Low Drifting dust, sand or snow/ Blowing dust, sand or snow/
Duststorm/ Sandstorm/ Thunderstorm (with or without precipitation)/ Squall/ Funnel
cloud (tornado or waterspout)/ Other weather phenomena if they are expected to cause
a significant change in visibility.
 The expected end of occurrence of the weather phenomena shall be indicated by the
abbreviation “NSW”.
 Format is [Intensity Or Proximity] [Descriptor] [Weather Phenomena]
Selection Criteria of weather elements: Normally, first consider the need for intensity,
followed by a descriptor and then weather phenomena (precipitation and/or obscuration).
No space is placed among the groups.
 Only one intensity and one descriptor shall be used for each weather group or
combination. Example: +SHRA
 Order of weather element: TS > RA > DZ
Intensity description:
56
 Intensity should be indicated only with precipitation, precipitation associated with
showers and/or thunderstorms, duststorm or sandstorm.
 Indicate Light intensity as (-), Heavy as (+) & no symbol for moderate intensity.
For Freezing Precipitation: A forecast of freezing precipitation is an exception to the
above rule.
 When one or more types of precipitation are forecasted and one is freezing (e.g. FZRA),
that type shall be encoded first regardless of the intensity.
 Intensity shall not be encoded with a second or third precipitation. For instance if heavy
snow and light freezing rain are forecast, the proper encoded is –FZRASN.
Special consideration for Thunderstorm: Thunderstorm (TS) is the only descriptor that
may be encoded without any associated precipitation.
 Whenever a thunderstorm is included in the weather group, even if in the vicinity, the
cloud group shall include a forecast cloud type of cumulonimbus.
 Intensity indicators refer only to the intensity of the precipitation associated with a
thunderstorm, not the intensity of the thunderstorm.
 There is no way to explicitly forecast a severe thunderstorm; however, a severe
thunderstorm can be indicated on the basis of the forecast winds, i.e. wind gusts of 50
knots or greater or forecast hail size of ¾ inch or greater.
Special Criteria for Obscuration (Visibility) Forecast:
 Encode BR (Mist) if the prevailing visibility is expected to be at least 1000 m but not
more than 5000 m and RH more than 75% & phenomena due to hydrometeors.
 Encode FG (Fog) when the prevailing visibility is expected to be less than 1000 meters.
 Encode MIFG (Shallow Fog) when the fog depth is less than six (6) feet and not expected
to obscure any part of the sky.
 Encode PRFG (Partial Fog) to describe fog "covering substantial part of the
aerodrome.”
 Encode BCFG (Patchy Fog) to describe fog patches randomly covering the aerodrome.
 Encode HZ (Haze) when visibility is 5000 m or less and RH less than 75% & phenomena
due to litho-meteors.
 Encode FU (Smoke) when visibility is 5000 m or less and obscuration is due to litho-
meteors.
 Encode DS (Duststorm) when visibility is 5000 m or less and obscuration is due to litho-
meteors.
 Encode SS (Sandstorm) when visibility is 5000 m or less and obscuration is due to litho-
meteors.

57
Special criteria for Weather CAVOK:
Example: TAF VECC 110500Z 1106/1212 04009KT CAVOK=
 The code CAVOK is frequently used in the TAF code, being the abbreviation for ‘Ceiling
(or cloud) and visibility are OK’
 If CAVOK is used, it will replace the Visibility, RVR, weather and cloud groups.
 There are four following criteria which must be met in order for CAVOK to appear in the
TAF.
1. The visibility must be 10 kilometres or more.
2. The height of the lowest cloud must be no less than 5000 feet, or the level of highest
minimum sector altitude, whichever is the greater.
3. There must be no cumulonimbus present.
4. There must be no significant weather
Cloud:
Cloud amount & height of base: (Inclusion criteria, M = inclusion mandatory, part of
every message)
Cloud type: (Inclusion criteria, C = inclusion conditional, dependent on meteorological
conditions)
General consideration:
 The group shall be in the initial time period line, all subsequent change lines as necessary.
 The cloud group can be repeated to indicate different layers or masses of cloud but the
number of groups should not normally exceed three with the following considerations:
Cloud amount (Sky cover):
 The lowest individual layer (mass) of with amount as FEW, SCT, BKN or OVC as
appropriate.
 The next individual layer of more than 2/8 as SCT, BKN, or OVC as appropriate.
 The next higher layer of more than 4/8 as BKN or OVC; and Cumulonimbus (CB)
and/or towering cumulus clouds (TCU), whenever observed and not already reported.
 When no cloud of operational significance is forecast, and “CAVOK” is not appropriate,
the abbreviation “NSC” shall be used.
 Vertical visibility is to be forecast in the form “VV” followed by the forecast value of
the vertical visibility when the sky is expected to remain or become obscured and clouds
cannot be forecast and information on vertical visibility is available.

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Height of cloud base:
 Encode the height of the base of each cloud layer in hundreds of feet AGL. This entry
follows the amount without a space.
 Express the height to the nearest 100 feet from the surface to 5,000 feet, to the nearest
500 feet from 5,000 feet to 10,000 feet; and to the nearest 1,000 feet above 10,000 feet.
 Layers from the surface to 50 feet are considered to be surface based and encoded as
000.
Cloud Type:
The only cloud type included in the TAF is cumulonimbus (CB).following the height in a
cloud group without a space, (i.e. BKN020CB). CB may be forecasted without the forecast
of a thunderstorm.
Change groups (Forecast Change Indicators):
Inclusion of Change group: Change groups are included as per following criteria:
 When the mean surface wind direction is forecasted to change by 60º or more, the mean
speed before and/or after the change being 10 kts or more;
 When the mean surface wind speed is forecasted to change by 10 kts or more;
 When the variation from the mean surface wind speed (gusts) is forecasted to increase
by 10 knots or more, the mean speed before and/or after the change being 15 knot or
more;
 Diurnal changes of surface wind (onset of sea breeze etc.), even if the changes do not
meet the above criteria.
 When the visibility is forecast to change to or pass through one or more of the following
values: 150, 350, 600, 800, 1500, 3000 or 5000 m;
 When any of the following weather phenomena or combinations thereof are forecasted
to begin or end or change in intensity -
• Freezing precipitation
• Moderate or heavy precipitation (including showers thereof)
• Thunderstorm (with precipitation)
• Duststorm
• Sandstorm
 When any of the following weather phenomena or combinations thereof are forecasted
to begin or end:
• Ice crystals
• Freezing fog

59
 • Low drifting dust, sand or snow
• Blowing dust, sand or snow
• Thunderstorm (without precipitation)
• Squall
• Funnel cloud (tornado or waterspout)
 When the height of base of the lowest layer or mass of cloud of BKN or OVC extent is
forecasted pass through one or more of the following values:
30, 60, 150, 300 or 450 m (100, 200, 500, 1000 or 1500 ft);
 When the amount of a layer or mass of cloud below 450 m (1500 ft) is forecasted to
change:
• From NSC, FEW or SCT to BKN or OVC; or
• From BKN or OVC to NSC, FEW or SCT;
 When the vertical visibility is forecast to pass through one or more of the following
values:
30, 60, 150, or 300 m (100,200,500 or 1000 ft)
 There are distinctive TAF codes which indicate that a change is expected in some or all
of the forecast meteorological conditions.
 The nature of the change can vary; it may, for instance, be a rapid, gradual or temporary
change.
Types of change group:
These codes are FM (meaning FROM), BECMG (meaning BECOMING), TEMPO
(meaning TEMPORARILY), and PROB (meaning PROBABILITY).
1. FROM (FM) Group:
 The FM indicator introduces what is effectively a new (permanent) forecast and
Change is from a point of time.
 The change indicator FM is followed by a four-digit time group in hours, and minutes,
to indicate the time at which the change is expected to begin.
Example: TAF VECC 130600Z 1307/1316 31015KT 8000 –SHRA SCT010 BKN018
FM 1220 27015KT 4000 BKN010 =
Explanation: From the above example, we read that, from 1220Z until the end of the
TAF period, the wind will change to be 270° at 15 knots, with a prevailing visibility of
4000 metres, and broken cloud at 1000 feet.
2. Becoming (BECMG) Group:

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 The code BECMG, marks a permanent change in the forecast weather, but which will
establish itself more gradually than weather conditions introduced by the code FM.
 BECMG is used to describe changes where the meteorological conditions are expected
to reach or pass through specified threshold values at a regular or irregular rate and at
an unspecified time during the time period. The time period shall normally not exceed
2 hours but in any case shall not exceed 4 hours.
 The BECMG indicator is followed by two four-digit sets, separated by a "/".
 The first four-digit set is a two-digit date followed by the two-digit beginning hour, and
the second four-digit set is a two-digit date followed by the two-digit ending hour
between which the change conditions is expected to occur.
Example:
TAF VECC 130600Z 1307/1316 31015KT 8000 –SHRA SCT010 BKN018 BECMG
1309/1311 5000 –RA =
Explanation: TAF indicates that at some time between the 0900 and 1100 UTC, but
definitely by 1100 UTC the prevailing conditions will give 5000 metres visibility, in
light rain. There is no new wind information after BECMG, so the implication is that the
wind will be as previously forecast value of 310° 15KT.
3. Temporary (TEMPO) Group:
 TEMPO is used for frequent or infrequent temporary fluctuations in the meteorological
conditions which reach or pass specified threshold values and last for a period of less
than one hour in each instance and, in the aggregate, cover less than one-half of the
forecast period generally 4 hours.
 The TEMPO indicator is followed by two four-digit sets, separated by a "/".
 The first four-digit set is a two-digit date followed by the two-digit beginning hour, and
the second four-digit set is a two-digit date followed by the two-digit ending hour
between which the temporary change conditions is expected to begin and end.
Example:
TAF VECC 130600Z 1307/1316 31015KT 8000 KT –SHRA SCT010 BKN018 TEMPO
1312/1314 4000 TSRA BKN010CB =
Explanation: TAF tells us that sometime between 1200 UTC and 1400 UTC, the
visibility will fall 4000 metres, with the weather being thunderstorms and moderate rain.
There will be 5 to 7 oktas of cumulonimbus cloud at 1000 feet.
4. The Probability (PROB) Indicator:
 The code PROB in a TAF indicates the probability of the occurrence of specified weather
phenomena. There are two type of PROB:
i. PROB30: indicates a low probability of a change occurring.
ii. PROB40: indicates a high probability of a change occurring.
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 The code PROB can be followed by a time group of its own, and/or by an indicator, such
as BECMG or TEMPO.
Example:
TAF VECC 130600Z 1307/1316 31015KT 8000 –SHRA SCT010 BKN018 PROB40
TEMPO 1310/1314 +TSRAGR SCT005CB =
Explanation: The above example of TAF tells us that there is a high probability that,
between 1000 UTC and 1400 UTC, there will be thunderstorms with heavy rain and hail,
and from 3 to 4 oktas of cumulonimbus clouds at 500 feet.
End of Message:
An equals sign (=) appears at the end of the TAF reports to denote that the message is
complete.
Example:
TAF VECC 110500Z 1106/1212 19008KT 3500 HZ SCT018 BKN100
TEMPO 1108/1112 2000 TSRA SCT015 FEW025CB OVC090
BECMG 1122/1124 2800 -RA HZ
BECMG 1203/1205 3500 -RA HZ
TEMPO 1205/1209 2000 TSRA SCT015 FEW025CB OVC090 =
Issue time & updation of TAF:
Long TAF (30 hour validity period) are scheduled four times daily (0000Z, 06000Z, 1200Z,
1800Z)
Short TAF (9 hour validity period) are scheduled eight times daily (0000Z, 0300Z 06000Z,
0900Z, 1200Z, 1500Z, 1800Z & 2100Z)
Issue time, schedule of updation & validity of short & long TAF are as follows:

Validity Period (UTC)

Issue Time 9 hours 30 hours
(UTC)
0200 03 -12
0500 06 -15 06-12
0800 09 -18
1100 12 -21 12- 18
1400 15 -24
1700 18 – 03 (next day) 18 - 00
2000 21 – 06
2300 00 - 09 00-06
Note: The 9 hourly TAF and 30 hourly are filed for departmental exchange 3 hours
before the start of the validity period. The 30 hourly TAF to international destination are
filed one hour before the beginning of validity period.
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4.3 ROUTE FORECAST (ROFOR)
4.3.1 General
Definition:
ROFOR is an abbreviation for "Route Forecast". As the name suggests it is the route
weather forecasts any aircraft between the point of departure and destination.
Form of ROFOR:
Route forecast are issued in:
1. Code form
2. Chart form and
3. Pictorial form
ROFOR is issued in coded form by AMOs and transmitted to AMSs for preparation of
route forecast between two specified aerodromes.
ROFOR is then decoded and MET-T4/ MET-T3 are prepared for handing over to pilot.
MET-T4 is used for flights beyond 500 nautical miles and MET-T3 is used for flight below
500 nautical miles.
4.3.2 Content of ROFOR
ROFOR contain upper winds, upper-air temperatures, and significant en-route weather
phenomena and associated clouds. Other elements namely-freezing (Icing) levels,
turbulence and vertical wind shear may be added as required. This information covers the
flight operations for which they are intended in respect of time, altitude and geographical
extent.
4.3.3 Steps for preparation of ROFOR
The preparation of Manual ROFOR involves following main steps:
 Aviation Forecast Order Form is filled by the duty Aviation officer at the briefing office
with the information provided by the Captain of the flight or the agency.
 Aviation Forecast Order Form is then forwarded /faxed to the Duty Forecaster.
 Duty Forecaster at briefing used this information to prepare a ROFOR.
 ROFOR prepared /filed at briefing to be collected by the ATS/pilot.
3.3.4 General Rules for Preparing Route Forecast (MET-T4)
1. Route forecast on MET-T4 is prepared in pictorial form for flight beyond 500 nautical
miles.
2. 0°C isotherm is to be drawn as a dashed line in blue or black and labelled 0°C on either
end.

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 3. Cloud amounts are to be indicated as SCT, BKN or OVC for all clouds other than CBs.
For CBs the terms ISOL, OCNL, or FRQ are to be used to indicate the frequency of
occurrence. The above terms are to be written either within the cloud or above it in
capital letters. Cloud types are to be indicated after the terms SCT, ISOL, etc.
4. The portion of the cloud depicted below the 0 0 C isotherm is to be shaded green while
the portion above 0 0 C isotherm is to be shaded red.
5. The following symbols are to be depicted in blue or black:

6. General information about flight should be entered in first page of MET-T4 form. It
contain Serial No. of flight, date of flight, flight number, ICAO name of AMO issuing
route forecast, route for which forecast is valid, date and time of issuing route forecast,
date and time of validity and Name of forecaster. And any other special information.
7. TAFORS of originating and destination along with their alternates and inference may be
given on first page under special information
4.3.5 Route Forecast (ROFOR) (For Decoding Into Met-T4 Form)
General Information
Serial No.: PQR-01
Flight number: IC-720
Date of flight: 15-12-2016
ROFOR 150100Z 150310KT VOMM VABB 03 VOHY 6000 SCT020 7060160 405026
27010 407020 27015 410013 36010 414002 09010 TEMPO 1509/1515 4000 TSRA
SCT015 7050/// FEWCB025 7340/// 651509 580256 OVC080 03 VAAU 6000 SCT020
7060160 405028 33015 407021 36015 410013 36010 414002 09010 TEMPO 1509/1515
3000 TSRA SCT015 7050/// 03 VABB 4000 HZ SCT025 7060160 405027 33015 407020
36015 410013 36010 414002 09010=
4.3.6 Preparation for plotting MET-T4
ROFOR Message indicator
150100Z Date and Time of issue in UTC Issued on 15th day of the month at 0100 UTC
150310KT Period of validity
On 15th Day of the month & valid from 0300 to 1000 UTC
VOMM- ROFOR is from Chennai to Mumbai
VABB
VOHY This division of route on Station basis i.e. Route forecast is up to Hyderabad
6000 Visibility group: Visibility is 6000 m
SCT020 Cloud group: SCT is amount & type of cloud, 020 base of cloud

64
7060160 This group is top (height) of cloud & height of freezing level. 070 is top of cloud
whose base is 020 & freezing level is 160
405026 Indicator of flight level (height) and corresponding temperature, 050 is flight level
(height) and 26 (plus 26°C) is temperature at flight level (height) 050
27010 This is wind direction and wind speed,270° is wind direction
& 10 kts is wind speed at flight level (height) 050
407020 Indicator of flight level (height) and corresponding temperature, 070 is flight level
(height) and 20 (plus 20°C) is temperature at flight level (height) 070
27015 This is wind direction and wind speed, 270° is wind direction
& 15 kts is wind speed at flight level (height) 070
410013 Indicator of flight level (height) and corresponding temperature, 100 is flight level
(height) and 13 (plus 13°C) is temperature at flight level (height) 100
36010 This is wind direction and wind speed, 360° is wind direction
& 10 kts is wind speed at flight level (height) 100
414002 Indicator of flight level (height) and corresponding temperature, 140 is flight level
(height) and 02 (plus 02°C) is temperature at flight level (height) 140
09010 This is wind direction and wind speed, 090° is wind direction
& 10 kts is wind speed at flight level (height) 140
TEMPO This is the change indicator, temporary fluctuation in meteorological parameter

1509/1515Date and validity temporary fluctuation, 15 is date, change is expected from 0900
to 1500 UTC
4000 Reduction in visibility to 4000 M
TSRA Weather group as the supplementary phenomena is Thunderstorm
FEWCB025 FEW amount & type of cloud is CB, 025 base of CB cloud
7340/// 340 is Top of CB, /// - no freezing level forecast as it has already given (160)
651509 This is icing group, 5 is type of icing at base height (flight level) 150 and thickness
is 9. The base of icing is at 150 and top is (150*30 + 9*300)/30 = 240

580256 This is turbulence group, 8 is type of turbulence at base height 025 flight level and
thickness 6. The base of turbulence 025 & top is (025*30 + 6*300)/30 = 085

OVC080 Cloud group BKN is amount & type of cloud, 080 is the base of
cloud
03 VAAU This division of route on Station basis i.e. Route forecast is up to Aurangabad
6000 Visibility
SCT020 Cloud group: SCT is amount & type of cloud, 020 base of cloud
7060160 This group is top (height) of cloud & height of freezing level. 070 is top of cloud
whose base is 020 & freezing level is 160
405028 Indicator of flight level (height) and corresponding temperature, 050 is flight level
(height) and 28 (plus 28°C) is temperature at flight level (height) 050
33015 This is wind direction and wind speed, 330° is wind direction

65
 & 15 kts is wind speed at flight level (height) 050

407021 Indicator of flight level (height) and corresponding temperature, 070 is flight level
(height) and 21 (plus 21°C) is temperature at flight level (height) 070
36015 This is wind direction and wind speed, 360° is wind direction
& 15 kts is wind speed at flight level (height) 070
410013 Indicator of flight level (height) and corresponding temperature, 100 is flight level
(height) and 13 (plus 13°C) is temperature at flight level (height) 100
36010 This is wind direction and wind speed, 360° is wind direction
& 10 kts is wind speed at flight level (height) 100
414002 Indicator of flight level (height) and corresponding temperature, 140 is flight level
(height) and 02 (plus 02°C) is temperature at flight level (height) 140
09010 This is wind direction and wind speed, 090° is wind direction
& 10 kts is wind speed at flight level (height) 140
TEMPO This is the change indicator, temporary fluctuation in meteorological parameter
1509/1515 Date and validity temporary fluctuation, 15 is date, change is expected from 0900
to 1500 UTC
3000 Reduction in visibility to 3000 M
TSRA Weather group as the supplementary phenomena is Thunderstorm
03 VABB This division of route on Station basis i.e. Route forecast is up to Mumbai
4000 Visibility
HZ Weather Group is Haze
SCT025 Cloud group: SCT is amount & type of cloud, 025 base of cloud
760160 This group is top (height) of cloud & height of freezing level. 070 is top of cloud
whose base is 020 & freezing level is 160
405027 Indicator of flight level (height) and corresponding temperature, 050 is flight level
(height) and 27 (plus 27°C) is temperature at flight level (height) 050
33015 This is wind direction and wind speed, 330° is wind direction
& 15 kts is wind speed at flight level (height) 050
407020 Indicator of flight level (height) and corresponding temperature, 070 is flight level
(height) and 20 (plus 20°C) is temperature at flight level (height) 070
36015 This is wind direction and wind speed, 360° is wind direction
& 15 kts is wind speed at flight level (height) 070
410013 Indicator of flight level (height) and corresponding temperature, 100 is flight level
(height) and 13 (plus 13°C) is temperature at flight level (height) 100
36010 This is wind direction and wind speed, 360° is wind direction
& 10 kts is wind speed at flight level (height) 100
414002 Indicator of flight level (height) and corresponding temperature, 140 is flight level
(height) and 02 (plus 02°C) is temperature at flight level (height) 140
09010 This is wind direction and wind speed, 090° is wind direction
& 10 kts is wind speed at flight level (height) 140

66
 # Kindly refer to Appendix-IV for Met-T4 Format
4.3.7 General Rules for Preparing Route Forecast (Met-T3)
1. MET T3 is the route forecast in tabular form.
2. General information about flight should be entered in first page of MET-T3 form. It
contain Serial No. of flight, date and time of flight forecast issued, flight number, ICAO
name of AMO issuing route forecast, route for which forecast is valid, and Name of
forecaster and any other special information which is significant for the flight also may
be provided.
3. Date and time of issuing route forecast, date and time of validity.
4. TAFORs of originating and destination along with their alternates and inference may be
given on first page under special information.
5. Cloud amounts are to be indicated as SCT, BKN or OVC for all clouds other than CBs.
For CBs the terms ISOL, OCNL, or FRQ are to be used to indicate the frequency of
occurrence. Cloud types are written in capital letters.
4.3.8 Route Forecast (ROFOR) (For Decoding Into Met-T3 Form)
General Information
Serial No.: PQR-02
Flight number: VUBNH
Date of flight: 13-05-2020
ROFOR 130030Z 200610KT VECC-VANP 2800 HZFEW020 7024140 SCT090 405022
24010 407015 22015 410010 21010 414001 19005 BECMG 1303/1305 4000 HZ=

ROFOR Message Identifier

130030Z Date and Time of issue in UTC e.g. On 13th Date & issued at 0030UTC
200610KT Date & Time of validity e.g. On 13th Date & valid from
0300 to 1000UTC
VECC-VANP ROFOR is from Kolkata to Nagpur
2800 Visibility
HZ Weather along the route here weather is Haze
FEW020 Cloud group: FEW amount & type of cloud, 020 base of cloud
7024140 This group is top (height) of cloud & height of freezing level. 024 is top of cloud
whose base is 020 & freezing level is 140
SCT090 Cloud group: SCT amount & type of cloud, 090 base of
cloud
405022 Indicator of flight level (height) and corresponding temperature, 050 is flight
level (height) and 22 (Plus 220C) is temperature at flight level (height) 050

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 24010 This is wind direction and wind speed group, 2400 is wind direction & 10KT is
wind speed
407015 Indicator of flight level (height) and corresponding temperature, 070 is flight
level (height) and 15 (Plus 150C) is temperature at flight level (height) 070
22015 This is wind direction and wind speed group, 2200 is wind
direction & 15KT
410010 Indicator of flight level (height) and corresponding temperature, 100 is flight
level (height) and 10 (Plus 100C)
is temperature at flight level (height) 100
21010 This is wind direction and wind speed, 2500 is wind
direction & 15Kt is wind speed at flight level (height) 070
414001 Indicator of flight level (height) and corresponding temperature,
140 is flight level (height) and 01 (Plus 010C)
is temperature at flight level (height) 140
19005 This is wind direction and wind speed 1900 is wind direction & 05KT is wind
speed at flight level (height) 140
BECMG Change group indicator
1303/1305 Date and validity period of the temporary fluctuation, 13 is date, The fluctuation
in conditions are expected from 0300 to 0500 UTC.
4000 Improvement in visibility to 4000 M in HZ

# Kindly refer to Appendix-IV for Met-T4 Format

4.4 LOCAL/AREA FORECAST
4.4.1 Purpose
These are issued for the use of low-level flights including helicopters.
4.4.2 Issuing authority
MWOs/ AMOs in India shall issue Local forecasts for their own aerodromes & Area
forecasts for the AMSs under their control as per requirement.
4.4.3 Coverage area
Both are valid over the aerodrome and 100 NM around.
4.4.7 Frequency of issue & Validity
Local and Area forecasts are to be issued three times a day, where ATC watch is maintained
for 24 hrs. Each forecast shall be valid for the next 8 hours.
4.4.8 Schedule of issue with validity period
Issued at (UTC) Valid for (UTC)
2130 2200-0600
0530 0600-1400

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 1330 1400-2200

Note: At aerodromes, where the ATC maintains only restricted watch, Local and Area
forecasts are to be issued to cover the ATC watch hour period.
4.4.9 Template for Local/Area Forecast
Both Local and Area Forecasts are issued in the same template (Met-T2) given below.
4.5 TREND FORECAST/LANDING FORECAST:
4.5.1 Purpose & coverage area
Landing forecasts issued in India as a routine are called trend forecast also.
These forecasts are intended to meet the requirements of local users and of aircraft within
about one hour’s flying time from the aerodrome.
4.5.2 Issuing authority
All Aerodrome Meteorological Offices (with forecasting facility) issue TREND forecasts
during the forecast watch hours.
4.5.3 Frequency of issue & Validity
 They are appended to a local routine or local special report, or a METAR or SPECI as
and when situation arises i.e. when significant changes in respect of one or more of the
elements: surface wind, visibility, weather and clouds is/are expected.
 The period of validity of a trend forecast shall be 2 hours from the time of the report,
which forms part of the landing forecast.
4.5.4 Change indicators
1. When a change is expected to occur, the trend forecast message should begin with one
of the change indicators “BECMG” or “TEMPO”.
2. The trend forecast indicates significant changes in respect of one or more of the
elements: surface wind, visibility, weather and clouds.
3. Only those elements are included for which a significant change is expected.
4. However, in the case of significant changes in respect of cloud, all cloud groups,
including layers, or masses not expected to change, shall be indicated.
5. In the case of a significant change in visibility, the phenomenon causing the reduction
of visibility should also be indicated.
6. When no change is expected to occur, this shall be indicated by the term “NOSIG”.
Surface Wind:
The trend forecast for surface wind is issued for the following conditions:
1. Change in the mean wind direction of 600 or more, the mean speed before and/or after
the change being 10 kts or more;
69
2. Change in mean wind speed of 10 kts or more.
Example: An expected temporary fluctuation of surface wind from 250° at 35 kts with
maximum speed (gusts) to 50 kts throughout the period of the trend forecast is indicated
in the form:
“TEMPO 25035G50KT” in METAR and
“TEMPO 250/35KT MAX50” in METREPORT.
Visibility:
 Trend forecast for visibility is issued when it is expected to change to or pass through
any one of the values 150, 350, 600, 800, 1500, 3000 or 5000 m.
 Whenever reduction of visibility is indicated in trend forecasts in locally disseminated
reports, the reasons for such reduction in visibility is also specified in the trend part of
the message.
Example: A temporary reduction throughout the period of the trend forecast of the
visibility to 750 m in fog shall be rounded down to 700 m and indicated in the form:
“TEMPO 0700” in METAR and
“TEMPO VIS 700M” in MET REPORT.
Weather phenomena:
 The trend forecast should indicate the expected onset, cessation or change in intensity
of one or more of the following weather phenomena or combinations thereof:
 Freezing precipitation
 Moderate or heavy precipitation (including showers thereof)
 Thunderstorm (with precipitation)
 Duststorm
 Sandstorm
 Other weather phenomena if they are expected to cause a significant change in
visibility.
 The trend forecast should indicate the expected onset or cessation of one or more of the
following weather phenomena or combinations thereof:
 Ice crystals
 Freezing fog
 Low drifting dust, sand or snow
 Blowing dust, sand or snow
 Thunderstorm (without precipitation)

70
  Squall
 Funnel cloud (tornado or waterspout)
 The total number of phenomena reported in (a) and (b) should not exceed three.
 The expected end of the weather phenomena shall be indicated by the abbreviation
“NSW”.
Example:
1. “TEMPO FM0300 TL0430 TSRA” (METAR) and “TEMPO FM0300 TL0430
MOD TSRA” (local routine report).
2. An expected cessation at 1630 UTC, of significant weather, such as a
thunderstorm, is indicated in the form “BECMG AT1630 NSW” (in both METAR
and local routine report).
Cloud:
 Trend forecast should be issued when the height of the base of a cloud layer of BKN or
OVC extent is expected to change to or pass through one or more of the following
values: 30, 60, 150, 300 and 450 m (100, 200, 500, 1000 and 1500 ft).
 When the height of the base of a cloud layer is below or is expected to fall below or rise
above 450 m (1500 ft), the trend forecast should also indicate changes in cloud amount
from FEW, or SCT increasing to BKN or OVC, or changes from BKN or OVC
decreasing to FEW, or SCT.
 When no clouds of operational significance are forecast and “CAVOK” is not
appropriate, the abbreviation “NSC” should be used.
Vertical visibility:
 When the sky is expected to remain or become obscured and vertical visibility
observations are available at the aerodrome, and the vertical visibility is forecast to
change to or pass through one or more of the following values: 30, 60, 150, or 300m
(100, 200, 500, or1000 ft), the trend forecast should indicate the change.
4.5.6 Use of change group
BECMG:
 The change indicator “BECMG” is used to describe forecast changes where the
meteorological conditions are expected to reach or pass through specified values at a
regular or irregular rate.
 The period during which, or the time at which, the change is forecast to occur is
indicated, using the abbreviations FROM “FM”, TILL “TL”, or “AT”, as appropriate.
 They should be followed by a time group in hours (2 digit) and minutes (2 digit).

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 When the change is forecast to begin and end wholly within the trend forecast period,
the beginning and end of the change shall be indicated by using the abbreviations “FM”
and “TL” respectively with their associated time groups.
For example, for a trend forecast period from 1400 to 1600 UTC in the form, “BECMG
FM1430 TL1600” (in both METAR and local routine report).
TEMPO:
 The change indicator “TEMPO” is used to describe forecast temporary fluctuations in
the meteorological conditions which reach or pass specified values and last for a period
of less than one hour in each instance and, in the aggregate, cover less than one-half of
the period during which the fluctuations are forecast to occur.
 The period during which the temporary fluctuations are forecast to occur shall be
indicated, using the abbreviations “FM” and/or “TL”, as appropriate.
 They should be followed by a time group in hours and minutes.
Example: For a TREND forecast period from 1000 to 1200 UTC in the form “TEMPO
FM1030 TL1130” (in both METAR and local routine report).

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 Chapter - 5
WEATHER ADVISORY
SIGMET
5.1 INTRODUCTION
Definition:
SIGMET is shorthand for “Significant Meteorological Information. SIGMET is an in-
flight weather advisory concerning the occurrence or expected occurrence of specified
en-route weather phenomena (Significant Meteorological hazards) which may affect the
safety of aircraft operations.
5.2 ISSUING AUTHORITY
In India, SIGMET messages are issued by the MWOs at Mumbai, Kolkata, New Delhi
and Chennai for the respective Flight Information Regions. A SIGMET gives a concise
description of the phenomena in abbreviated plain language.
5.3 ISSUING TIME
The information may be about a hazardous weather phenomenon already occurring or it
may be for the expected occurrence of a phenomenon.
5.4 FORECASTING TOOL FOR SIGMET
Examine the following:
1. Surface pressure tendency: Rise/Fall
2. Low level moisture availability
3. Convection /convergence
4. Wind flow pattern & vertical wind shear.
5. Dry intrusion of air at or near mid tropospheric level
6. Size and distribution of CAPE & environmental lapse rates
7. Stability indices
8. Vorticity advection.
9. Upper level Jet.
10. NWP Model (Nowcast/Mesoscale)
11. Radar products (MAX Z, VVP-2)
12. Satellite imageries (Prevailing cloud pattern, movement & intensification)

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5.5 TYPES OF SIGMET
There are three types of SIGMETs:
1. SIGMET for volcanic ash, denoted as VA SIGMET or WV SIGMET
2. SIGMET for Tropical Cyclones, denoted as TC SIGMET or WC SIGMET
3. SIGMET for en-route weather phenomena other than VA and TC, (includes TS, CB,
TURB, ICE, MTW, DS, SS and RDOACT CLD) denoted as WS SIGMET.
5.6 DATA TYPE DESIGNATORS
The WMO data type designators used for dissemination of the SIGMETs are:
WC - SIGMET for Tropical Cyclones
WV - SIGMET for Volcanic Ash
WS - SIGMET other than volcanic ash cloud or tropical cyclone.
5.7 PERIOD OF VALIDITY
 The validity of a SIGMET message should not be more than 4 hours.
 In case of VA SIGMET and TC SIGMET, the period of validity can be extended up to
6 hours.
5.8 TIME OF ISSUE AND UPDATING FREQUENCY
 SIGMET messages should be issued not more than 4 hours before the commencement
of the period of validity.
 In case of VA SIGMET and TC SIGMET, these messages can be issued as soon as
practicable but not more than 12 hours before the commencement of the period of
validity.
 SIGMET messages for volcanic ash and tropical cyclones should be updated at least
every 6 hours.
5.9 SIGMET GUIDANCE CENTRES FOR TC & VA
 SIGMET messages concerning volcanic ash cloud and tropical cyclones shall be based
on advisory information provided by the designated VAACs and TCACs,
respectively.
 For India RSMC, New Delhi provide guidance for Tropical Cyclone & VAAC –
Darwin & VAAC Toulouse (France) provide advisories for Volcanic Ash cloud.
5.10 CANCELLATION OF SIGMET
SIGMET information shall be cancelled when the phenomena are no longer occurring or
no longer expected to occur in the FIR.
5.11 SPECIFICATION RELATED TO ISSUANCE OF SIGMET INFORMATION

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  SIGMET messages should be prepared in abbreviated plain language, using ICAO
approved abbreviations.
 Should be prepared in the template given.
 Messages containing SIGMET information shall be identified as “SIGMET”.
 The sequence number referred to in the template shall correspond with the number of
SIGMET messages issued for the FIR since 0001 UTC on the day concerned, e.g.,
“3” will be related to the Third SIGMET message issued by MWO since 0001 UTC
on the day concerned.
5.12 PHENOMENA TO BE INCLUDED IN A SIGMET MESSAGE
In accordance with the template, only one of the following phenomena shall be included
in a SIGMET message, using the abbreviations as indicated below irrespective of altitude.
Phenomena Abbreviation Description
OBSC TS Obscured thunderstorm(s)
EMBD TS Embedded thunderstorm(s)
FRQ TS Frequent thunderstorm(s)
TS SQL TS squall line thunderstorm(s)
OBSC TSGR obscured thunderstorm(s) with hail
EMBD TSGR Embedded thunderstorm(s) with hail
FRQ TSGR frequent thunderstorm(s) with hail
SQL TSGR squall line thunderstorm(s) with hail
TC Tropical cyclone
TC (+ Name of the Tropical (with 10 - minute mean surface wind speed
Cyclone, if known) of 34 kts or more)

TURB SEV TURB severe turbulence

ICE SEV ICE severe icing
SEV ICE (FZRA) severe icing due to freezing rain
MTW SEV MTW severe mountain wave
DS HVY DS heavy duststorm
HVY SS heavy sandstorm
VA VA volcanic ash
(+ Name of the Volcano,
if known)
5.13 CRITERIA RELATED TO PHENOMENA INCLUDED IN SIGMET MESSAGE
An area of Thunderstorms and cumulonimbus clouds shall be considered:
1. Obscured (OBSC) - If it is obscured by haze or smoke or cannot be readily seen due
to darkness.
2. Embedded (EMBD) - If it is embedded within cloud layers and cannot be readily
recognized.

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 3. Isolated (ISOL) - If it consists of individual features which affect, or are forecast to
affect, an area with a maximum spatial coverage less than 50 per cent of the area
concerned (at a fixed time or during the period of validity).
4. Occasional (OCNL) - If it consists of well-separated features which affect, or are
forecast to affect, an area with a maximum spatial coverage between 50 and 75 per
cent of the area concerned (at a fixed time or during the period of validity).
5. Frequent (FRQ) - An area of thunderstorms shall be considered frequent (FRQ) if
within that area there is little or no separation between adjacent thunderstorms with a
maximum spatial coverage greater than 75 per cent of the area affected or forecasted
to be affected, by the phenomenon (at a fixed time or during the period of validity).
6. Squall line (SQL) shall indicate a thunderstorm along a line with little or no space
between individual clouds.
7. Hail (GR) shall be used as further description of the thunderstorm, as necessary.
8. Severe and moderate turbulence (TURB) shall refer only to: low-level turbulence
associated with strong surface winds; rotor streaming; or turbulence whether in cloud
or not in cloud (CAT). Turbulence shall not be used in connection with convective
clouds. Note: Turbulence shall be considered:
9. Severe whenever the peak value of the cube root of eddy dissipation rate (EDR)
exceeds 0.7; and
10. Moderate whenever the peak value of the cube root of eddy dissipation rate (EDR) is
above 0.4 and below or equal to 0.7.
11. Severe and moderate icing (ICE) shall refer to icing in other than convective clouds.
Freezing rain (FZRA) shall refer to severe icing conditions caused by freezing rain.
5.14 SPECIAL CONSIDERATION/NOTE
The elements, turbulence and icing are assumed normally to be associated with an active
thunderstorm area, tropical revolving storm and severe line squall. They need not,
therefore, be specifically mentioned when SIGMET information is issued for active
thunderstorm area, tropical revolving storm and severe line squall.
Also the occurrence of heavy hail with thunderstorm shall be indicated.
5.15 TEMPLATE FOR SIGMET
Kindly refer to Appendix – IV.

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 Chapter - 6
AVIATION WEATHER WARNINGS

6.1 INTRODUCTION
Aviation weather warnings are given as:
1. Aerodrome warning (AW)
2. Light aircraft warning
3. Wind shear warning
6.2 AERODROME WARNING (AW)
6.2.1 Purpose
AWW gives concise information of meteorological conditions, which could adversely affect
aircraft on the ground, including parked aircraft and the aerodrome facilities and services.
Information contained in this product is useful to airport managers, airport based
operators, airline ground personnel, and others responsible for the safety of ground
operations.
6.2.2 When to Issue & for Whom
They can be issued for an observed phenomenon or for the expected occurrence of a
phenomenon that could adversely affect aircraft on the ground, including parked aircraft
and the aerodrome facilities and services.
Aerodrome warnings are issued only for the local aerodrome as they are meant for
protection of the aircraft parked and aerodrome facilities.
6.2.3 Issuing Authority
Issued by all MWOs/AMOs during period of forecast watch hour as & when required.
For aerodromes with AMS, these warnings are issued by the associated Aerodrome
Meteorological Office.
Outside the forecast watch period of any station, the responsibility is transferred to the
concerned AMO or to the MWO.
6.2.4 Format for Issue
The AWW warnings are to be issued in the template given below.
6.2.5 Template for Aerodrome Warning
Kindly refer to Appendix – IV.
6.2.6 Time of Updation & Validity Period

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 The aerodrome warnings for the expected occurrence of the phenomena shall be issued at
least half to one hour prior to the expected occurrence of the warning elements.
The period of warning shall preferably be short, not exceeding 4 hours. If the phenomena
are expected to continue for a longer time, a fresh warning may be issued suitably.
6.2.7 Cancellation of Aerodrome Warning
Aerodrome warnings shall be cancelled when the phenomena are no longer occurring or
are no longer expected to occur at the aerodrome.
Cancellation message also should be issued as per the template.
6.2.8 Elements of Aerodrome warning
Aerodrome warnings shall relate to the occurrence or expected occurrence of one or more
of the following phenomena:
1. Tropical cyclone: (To be included if the 10 minute mean surface wind speed at the
aerodrome is expected to be 34 kts or more)
2. Thunderstorm
3. Hail
4. Snow (including the expected or observed snow accumulation)
5. Freezing precipitation
6. Hoar Frost or rime
7. Duststorm
8. Sandstorm
9. Rising sand or dust.
10. Strong surface wind and gusts:
a. Speed expected to reach 30 kts or more even in gusts.
b. Direction change rapidly by >= 45°, wind speed before and after expected to be >=
20 kts.
11. Squall: Whenever expected, the expected direction and speed shall be indicated.
12. Frost
13. Volcanic ash
14. Tsunami
Note: Reduction in visibility and lowering of cloud base associated with the warning
elements should not be mentioned in warnings separately.

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6.2.9 Transmission
The warnings are to be passed on to local ATS units, Airport managers for further
dissemination over a particular aerodrome and to the operators, etc. These are not to be
disseminated beyond the aerodrome of origin. The warning should also be updated in
OLBS system.
6.2.10 Verification of Aerodrome warnings
General rule for verification of Aerodrome warnings:
 All the aerodrome warnings issued by the station are to be verified.
 Only the expected/forecast occurrence of the warning elements is to be verified.
 There shall only be “correct” and “incorrect” categories. There shall not be
“partially correct” category as per this criterion.
 For each element, a minimum of 80% of cases percentage within range shall be
considered desirable/ satisfactory.
Example: Out of 100 forecasts of an element, at least on 80 occasions, the forecast
shall be correct.
Criteria for verification of Aerodrome warnings:
Weather phenomena: Occurrence or non-occurrence.
 If in the aerodrome warning, a weather phenomenon is expected to affect the
aerodrome and if it occurs, then warning is to be considered as correct.
 In case of expected occurrence of thunderstorms, if lightning is observed or thunder
is heard, the warning may be taken as correct.
 If, CB is observed at the station, then also the warning may be taken as correct
Surface wind: (For “Strong surface wind and gusts”, and for “Squall”)
Speed: ± 5 knots; i.e., when the deviation of the forecast speed from the observed
speed is 5 knots, the warning may be taken as correct. Otherwise it may be taken as
wrong.
Wind Direction: ± 30°; the warning may be taken as correct when the expected
direction differs from the actual direction by 30° or less.
In cases of aerodrome warning for rapid wind direction change by 45 degrees or
more of wind with a speed of 20 KT or more, the occurrence of the event may be
taken as “correct” and non-occurrence as “wrong”.
Proforma for verification of Aerodrome forecast:
For Proforma for verification of Aerodrome Warning, please refer to Appendix.

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6.3 WARNING FOR LIGHT AIRCRAFTS
6.3.1 Purpose
Apart from the aerodrome warnings issued, warnings for gliders, light aircraft and
helicopters are to be issued separately when wind speed is expected to reach 17KT or
more.
They should also be appended to local forecast.
6.3.2 Issuing Authority
All AMOs/MWOs issues light aircraft warning during operational watch hour.
They are to be issued with the prefix “Warnings for Light Aircraft” in abbreviated plain
language.
6.3.3 Format
Format of light aircraft warning is similar to the format of aerodrome warning except it
is issue with the prefix “Warnings for Light Aircraft”.
6.3.4 Cancellation of Warning
The warning is cancelled when wind speed no longer exists/expected to exit 17KT or
more.
6.3.5 Transmission
The warnings are to be passed on to local ATS units, Airport managers for further
dissemination over a particular aerodrome and to the operators, etc.
These are not to be disseminated beyond the aerodrome of origin. Also updated in OLBS
system.
6.4 WIND SHEAR WARNING
6.4.1 Phenomena Associated with Wind Shear Warning
Wind shear conditions are normally associated with the following phenomena:
1. Thunderstorms, Microbursts, Funnel cloud (tornado or waterspout), and Gust
fronts
2. Frontal surfaces
3. Strong surface winds coupled with local topography
4. Sea breeze fronts
5. Mountain waves (including low-level rotors in the terminal area)
6. Low-level temperature inversions
6.4.2 Content & Purpose

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 Wind shear warnings shall give concise information on the observed or expected
existence of wind shear which could adversely affect aircraft on the approach path or
take-off path or during circling approach between runway level and 500 m (1600 ft) above
that level and aircraft on the runway during the landing roll or take-off run.
6.4.3 Detection of Wind Shear
Evidence of the existence of wind shear shall be derived from:
1. Ground-based wind shear remote-sensing equipment, for example, Doppler Radar;
2. Ground-based, wind shear detection equipment, for example, a system of surface wind
and/or pressure sensors located in an array monitoring a specific runway or runways
and associated approach and departure paths;
3. Aircraft observations during the climb-out or approach phases of flight to be made in
accordance with the provisions of
4. Aircraft Observations and Reports;
6.4.4 Issuing Authority & When to Issue
Wind shear warnings shall be prepared by AMOs/MWOs when detected.
6.4.5 Criteria for Issue
1. The warnings shall be prepared and disseminated for aerodromes where wind shear is
considered a factor for aircraft safety.
2. Where local topography has been shown to produce significant wind shears at heights
in excess of 500 m (1600 ft) above runway level, then 500 m (1600 ft) shall not be
considered restrictive.
6.4.6 Procedure of Issue & Transmission
Wind shear warnings shall be issued in accordance with the template and shall be
disseminated in accordance with local arrangements to those concerned.
The sequence number referred to in the template shall correspond with the number of
wind shear warnings issued for the aerodrome since 0001 UTC on the day concerned.
6.4.7 Format and Dissemination of Wind Shear Warning
Information on wind shear is also to be included as supplementary information in local
routine and special reports and METAR and SPECI in accordance with the respective
templates.
When an aircraft report is used to prepare a wind shear warning, or to confirm a warning
previously issued, the corresponding aircraft report, including the aircraft type, shall be
disseminated unchanged in the warning, in the form, “WS WRNG B747 REPORTED
MOD WS IN APCH RWY 34 AT 1510”.

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 Where microbursts are observed, reported by pilots, or detected by ground-based, wind
shear detection or remote-sensing equipment, the wind shear warning shall include a
specific reference to microburst, for example, “WS WRNG MBST APCH RWY 26”.
Following reported encounters by both arriving and departing aircraft two different wind
shear warnings may exist: one for arriving aircraft and one for departing aircraft.
6.4.8 Template for Wind Shear Warning
Kindly refer to Appendix – IV.
6.4.9 Intensity Report by Pilot:
Pilots, when reporting wind shear, may use the qualifying terms “moderate”, “strong” or
“severe”, based to a large extent on their subjective assessment of the intensity of the
wind shear encountered.
6.4.10 Cancellation of Wind Shear:
Wind shear warning for arriving aircraft and/or departing aircraft shall be cancelled when
aircraft reports indicate that wind shear no longer exists, or alternatively after an elapsed
time of two hours.

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 Chapter - 7
BRIEFING, DE-BRIEFING AND DOCUMENTATION

7.1 BRIEFING
7.1.1 Role of AMOs /MWOs
Aviation Meteorological Offices should supply the meteorological information to
operators and flight crewmembers for:
1. Pre-flight planning by operators;
2. In-flight re-planning by operators using centralised operational control of flight
operations;
3. Use by flight crew members before departure; and
4. Aircraft in flight.
7.1.2 Purpose of Briefing
The purpose of briefing is to supply the latest available information on existing and
expected meteorological conditions along the route to be flown, at the aerodrome of
intended landing, alternate aerodromes as relevant, either to explain and amplify the
information contained in the flight documentation or in lieu of flight documentation.
7.1.3 Briefing requirement of National flight (Information to be provided)
Meteorological information supplied to operators and flight crewmembers should be up
to date and include the following information:
1. Forecasts of
a. Upper wind and upper air temperature;
b. Flight level and temperature of tropopause;
c. Direction, speed and flight level of maximum wind; and
d. SIGWX phenomena.
2. METAR and SPECI (including trend forecasts) for the aerodromes of departure and
intended landing, and for take-off, en-route and destination alternate aerodromes;
3. TAF or amended TAF for the aerodromes of departure and intended landing, and for
take-off, en-route and destination alternate aerodromes;
4. Forecasts for take-off;
5. SIGMET information, and appropriate special air-reports relevant to the whole route,
those not already used in the preparation of SIGMET;
6. Volcanic ash and tropical cyclone advisory information relevant to the whole route;

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 7. Area forecast/local forecast;
8. Aerodrome warnings for local aerodrome;
9. Meteorological satellite images; and
10. Ground- based weather radar information
7.1.4 Briefing requirement for International flight
Forecasts listed for supplying to international flights shall be generated from the digital
forecasts provided by the WAFCs whenever these forecasts cover the intended flight path
in respect of time, altitude and geographical extent.
When forecasts are identified as being originated by the WAFCs, no modifications shall
be made to their meteorological content.
7.1.5 Mode of supply
Meteorological information can be supplied by one or more of the following methods
(order shown below not implying priorities):
1. Written or printed material, including specified charts and forms;
2. Data in digital form;
3. Briefing;
4. Consultation; or
5. Display.
6. Online briefing system (OLBS) through following URL:
a. http://olbs.amsschennai.gov.in/nsweb/FlightBriefing/#showLogin
b. http://olbs.amssdelhi.gov.in/nsweb/FlightBriefing/#showLogin
7.1.6 Supply of information & role of Forecasting office
The required briefing, consultation, display and/or flight documentation shall normally
be provided by the AMOs at the aerodrome of departure.
If the meteorological office at the aerodrome of departure happens to be an AMS that
office will provide necessary flight documentation after obtaining the same from the
associated AMO.The required information shall be supplied at the location of the
meteorological office.
The flight crew member or other flight operations personnel for whom briefing,
consultation and/or flight documentation has been requested shall visit the meteorological
office in person for receiving the necessary meteorological briefing three hours prior to
the scheduled time of departure.
Where local circumstances at an aerodrome make personal briefing or consultation not
practicable, the meteorological office shall provide those services by telephone or other

84
 suitable telecommunication facilities. The service shall normally be confined to flights
originating within the country.
7.1.7 Time schedule of supply of information
The upper wind and upper-air temperature information and the significant en-route
weather information for pre-flight planning and in-flight re planning by operators shall
be supplied as soon as it becomes available, but not later than 3 hours before departure.
Other meteorological information requested for pre-flight planning and in-flight re-
planning by operators shall be supplied as soon as is practicable.
7.1.8 Specific requirement for briefing of low-level flights (Helicopter)
Briefing and/or consultation for low-level flights including those in accordance with the
visual flight rules, should include meteorological information covering altitudes up to
flight level 100 (or up to flight level 150 in mountainous areas or higher, when necessary).
Particular mention should be made of the occurrence or expected occurrence of any
phenomena causing widespread reduction of visibility to less than 5000 m, as well as the
occurrence or expected occurrence of clouds, which may affect the flight.
Information from relevant SIGMET message also may be provided.
7.1.9 Provision for amendment of briefing document
If the meteorological office expresses an opinion on the development of meteorological
conditions at an aerodrome, which differs appreciably from the aerodrome forecast
included in the flight documentation, the attention of the flight crewmembers shall be
drawn to the divergence. The portion of the briefing dealing with the divergence shall be
recorded at the time of briefing and this record shall be made available to the operator.
7.1.10 Requirement of display system
To assist the flight crewmembers and others concerned with the preparation of the flight and
for use in briefing and consultation, the meteorological office shall display the latest available
information for ready access to the users.
7.1.11 Procedures to be followed when briefing & documentation facility is
not available to a particular station
If an aircraft makes a stop at aerodromes at which briefing and documentation are not
normally available for the flight, the following procedures will be followed:
1. If the meteorological office at such stop happens to be an AMO, it shall make available
to the flight crew the most recent aerodrome forecasts available relevant to the flight
and the most recent meteorological reports available relevant to the continuation of
the flight. If fresh briefing and documentation is requested by the flight crew due to
the delay in flight, etc., the meteorological office shall prepare and supply necessary
documentation and provide briefing.
2. If the meteorological office at such halt happens to be an AMS, it shall make available
the most recent meteorological reports available relevant to the continuation of the

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 flight; if documentation is requested the same may be obtained from the associated
Aerodrome Meteorological Office and provided.
7.2 DE-BRIEFING
The popular meaning of debriefing is telling about what type of flight weather
encountered during en-route. The experience is shared by flight crew member to the Met
duty officer at the termination of a flight journey.
7.3 FLIGHT DOCUMENTATION
7.3.1 Documentation of National Flight
1. Content of documentation of National flight
Flight documentation shall cover the whole route to be flown and comprise
information listed below:
a. Forecasts of Upper wind and upper air temperature; and SIGWX phenomena.
b. METAR and SPECI (including trend forecasts) for the aerodromes of departure and
intended landing, and for take-off, en-route and destination alternate aerodromes;
c. TAF or amended TAF for the aerodromes of departure and intended landing, and
for take-off, en-route and destination alternate aerodromes;
d. SIGMET information, and appropriate special air-reports relevant to the whole
route, those not already used in the preparation of SIGMET;
e. Volcanic ash and tropical cyclone advisory information relevant to the whole route
(the information received from other meteorological offices shall be included in
flight documentation without change); and
f. Area forecast/ local forecast;
2. Procedure for documentation of National Flight:
a. The flight documentation for national flights shall be presented in the form of
charts, tabular forms or abbreviated plain language texts.
b. METAR, SPECI, TAF, and SIGMET received from other meteorological offices
shall be included in flight documentation without change.
c. TAF shall be presented in code form or abbreviated plain language texts.
d. The forms and the legend of charts in flight documentation should be printed in
English.
e. The units employed for each element shall be indicated.
f. The location indicators and the abbreviations used should be explained in the flight
documentation.
g. The documentation is to be handed over only to DGCA certified Flight Dispatcher/
Pilots.

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7.3.2 Procedure for documentation of International Flight
For flight documentation of international flights, meteorological offices shall provide
information received within the framework of WAFS using WAFC SIGWX Chart.
TAF shall be presented in code form or abbreviated plain language texts.
Examples of WAFC SIGWX Chart and upper air wind and temperature forecast are given
in Appendix -
Examples of route forecast in Met-T4 and Met-T3 forms. National SIGWX charts are also
given as Appendix -
7.3.3 Amendment of flight documentation
 Where a need for amendment arises after flight documentation has been supplied, and
 Before take-off of the aircraft, the meteorological office shall issue the necessary
amendment or updated information to the operator or to the local air traffic services
unit, for transmission to the aircraft.
7.3.4 Retention of Documentation:
 The meteorological offices shall retain information supplied to flight crewmembers
as printed copies and as computer files, for a period of at least 180 days from the date
of issue.
 This information shall be made available, on request, for inquiries or investigations
and, for these purposes, shall be retained until the inquiry or investigation is
completed.
 Log in details of briefing provided through OLBS is also to be retained in hard copy
form as well as in the form of computer files.
7.3.5 Set of charts to be provided
The actual charts provided for pre-flight and in-flight planning and for flight
documentation shall be based on the user’s requirement. Charts to be provided shall be
generated from the digital forecasts provided by the WAFCs whenever these forecasts
cover the intended flight path in respect of time, altitude and geographical extent.
7.3.6 Procedures for supply of documentation by AMO/AMS
 For all International flights, originating from AMOs, documentation shall be supplied
in chart form, as obtained from WAFC. Chart form of documentation shall also be
supplied to international flights originating from airports served by AMSs by
obtaining the same from the associated AMOs.
 For all National flights documentation shall be supplied as follows:
1. For all national flights, national SIGWX charts along with WAFC upper wind and
temperature charts shall be provided wherever FAX/internet facility is available.

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 2. At other stations, documentation shall be provided in Met.T-3 form for flights of
500 nautical miles or less and in Met.T-4 form for flights exceeding 500 nautical
miles.
 For all services the forecasting office at the starting station shall provide
documentation and briefing up to the next aerodrome of landing where a forecasting
office (Civil/IAF) is functioning. The forecasting offices at such intermediate halts
shall in turn, provide fresh briefing and documentation. For such of these flights
whose duration of halt at intermediate stations is 75 minutes or less, through
documentation and briefing, shall be provided by the forecasting offices at the starting
station. AMOs at intermediate halts need not provide fresh documentation for such
flights.
 AMOs at intermediate halts shall supply to the local air traffic control units,
METARs/SPECIs of stations ahead on the route up to a distance of 2 hours flying
time, so that the ATC can transmit these observations directly to the aircraft. The
required current weather observations shall be obtained on the departmental
telecommunication channels.
 Wind and temperature data required for flight planning purposes shall be provided by
the starting station for the entire route as required.
 For flights starting from an aerodrome with an AMO and returning from another
aerodrome with an AMO, briefing and documentation for return flight also shall be
provided by the starting AMO. If the duration of the flight is covered by the validity
period of WAFC products or the validity period of the national significant weather
charts, fresh briefing or documentation need not be supplied to the aircraft for the
return flights if the halt at the aerodrome is less than 75 minutes. However, briefing
shall be provided at the aerodrome of return flight whenever requested by pilots.
7.3.7 Supply of documentation by AMS
Documentation shall be provided as follows in respect of flights terminating at AMS and
returning from there as new flights:
1. AMO at the starting stations shall provide through documentation for the return flight
also if the flights are operating within the same region.
2. In case of delayed flights, if sufficient notice is available the documentation for the
return flight may be sent by ROFOR. If the station is connected by internet or has
FAX facility, chart form of documentation may be provided after obtaining the same
from the associated AMO.
3. In case of flights originating in one region and terminating in another region, and
starting from there as new flights, the documentation shall be provided on the basis
of ROFOR/ national SIGWX charts and WAFC upper air wind and temperature charts
supplied by the associated AMO in the region.
4. For all flights, an outlook of weather from the destination to one designated alternate
shall be supplied along with the documentation, on request.

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7.3.8 Procedure for supply of documentation in short notice
In respect of aircraft flights for which adequate notice is not available for preparation of
necessary documentation, and in such cases where the flight crew insists on
meteorological briefing without documentation, the following procedure shall be
followed:
1. The briefing shall cover the chief features of weather affecting the flight (including
visibility, clouds, upper winds and temperature as required). All available METARs /
SPECIs / RAREPs / SIGMETs etc. pertinent to the flight shall be shown to the crew
receiving briefing.
2. The details of briefing given as above shall be recorded under the heading “Main
points of briefing”, in the briefing register in the column ‘Briefing Notes.
3. The briefing notes shall be recorded in the presence of the aircrew receiving briefing,
who shall be requested to sign against the notes, in the appropriate column in the
briefing register.
4. The clearance form shall be signed by the Duty Officer with the remarks “Briefed
Captain/Mr. …………. Documentation not provided for want of adequate notice”.
Note: However, such oral briefings may be avoided as far as possible.
7.3.9 Inputs for preparation of Flight Documentation
Upper wind and upper air temperature:
a. The upper wind and temperature forecast charts issued by WAFC shall be used along
with the national SIGWX charts for the documentation of flights other than
international flights.
b. In Tabular and Cross Section forms of forecasts, upper wind and upper air temperature
information shall be given for the levels specified by the operators, for not more than
five levels.
c. This information shall be given for route segments.
d. Upper wind and upper air temperature charts for low level flights shall be supplied
for points separated by not more than 500 km (300NM) and for at least the following
altitudes:
600, 1500 and 3000m (2000, 5000 and 10000 ft).
7.3.10 Preparation of National significant weather (SIGWX) charts
As per latest decision (23.06.2020) NWP division of HQ will produce National significant
weather charts using NWP technique for the medium level (between FL 100 and FL 250)
and for high level (between FL 250 and FL 630).
Inclusion of 0° isotherm is necessary in the medium level chart.
7.3.11 Frequency, issue time & validity of National SIGWX charts

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  The charts shall be prepared four times a day based on 00, 06, 12 and 18 UTC
observations. The charts shall be issued 09 hours after the observation time i.e. a chart
based on 06 UTC observations will be issued and will be available for use by 1500
UTC.
 The charts will have a validity of 24 hrs. The issue time and validity of the national
SIGWX charts will be as follows:
Time of observation Time issue of chart (UTC) Validity
(UTC) (UTC)
00 09 00 next day
06 15 06 next day
12 21 12 next day
18 03 18 next day

 All Height indications will be in Flight Levels and the wind speeds will be in Knots.
7.3.12 Contents of the National SIGWX charts
The elements to be included in the high-level and medium-level SIGWX forecasts are as
follows:
1. Tropical cyclone, provided that the maximum of the 10-minute mean surface wind
speed is expected to reach or exceed 63 km/h (34kt);
2. Severe squall lines;
3. Moderate or severe turbulence (in cloud or clear air);
4. Moderate or severe icing;
5. Widespread sandstorm/duststorm;
6. Cumulonimbus clouds associated with thunderstorms and with 1 to 5;
7. Flight level of tropopause;
8. Jet-streams;
9. Information on the location of volcanic eruptions that are producing ash clouds of
significance to aircraft operations;
10. Information on the location of an accidental release of radioactive materials into the
atmosphere, of significance to aircraft operations.
Note: Non-convective cloud areas associated with in-cloud moderate or severe turbulence
and/or moderate or severe icing are to be included in the SIGWX forecasts.
7.3.13 Criteria for preparation of Flight Documentation Folder
Met.T-3 Format
In flight documentation provided in Met.T-3 form, the information given in flight
forecasts will include:

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 1. Significant features of synoptic situation;
2. Significant weather;
3. Cloud (amounts, types and heights of bases and tops);
4. Surface visibility;
5. Surface pressure data, if required;
6. Height of 0° C isotherm;
7. Upper winds and upper air temperature information;
8. General outlook.
Met T-4 Format
In flight documentation provided in Met.T-4 form the following information appropriate
to the flight shall be included:
1. Significant features of synoptic situation;
2. Significant en-route weather phenomena;
3. Clouds (amount and type of cloud);
4. Upper winds and upper air temperature information;
5. Surface pressure data, if required;
6. Height of 0° C isotherm;
7. Tropopause;
8. Surface visibility (only for flights below FL100).
7.3.14 List of Significant weather for inclusion in flight documentation folder
Information on significant weather included in Met T-4 and Met T-3 forms shall relate
to the occurrence of:
1. For high level flights:
a. Thunderstorm
b. Tropical cyclone
c. Squall line
d. Hail
e. Moderate or severe turbulence in cloud or clear air
f. Marked mountain waves and associated downdraft
g. Moderate or severe aircraft icing

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 h. Freezing precipitation
i. Widespread sandstorm/duststorm
2. For low level flights (up to FL100):
a. Thunderstorm
b. Tropical cyclone
c. Squall line
d. Hail
e. Moderate or severe turbulence in cloud or clear air
f. Mountain waves and associated downdrafts
g. Aircraft icing
h. Freezing precipitation
i. Widespread sandstorm/dust storm
j. Fog
k. Precipitation
l. Other phenomena causing widespread reduction of visibility to less than 5000
meters.
7.3.15 Flight documentation: Aerodrome forecasts
 The flight documentation shall in all cases include aerodrome forecasts for the
aerodrome of departure, the destination aerodrome and for take-off, en-route and
destination aerodromes and alternates.
 The period of validity of the aerodrome forecast shall cover at least one hour before
ETA at the destination and 2 hours after the ETA at the farthermost alternate.
 Aerodrome forecasts received from other meteorological offices shall be included in
flight documentation without change in substance.
 A Meteorological Office providing documentation shall make all practicable efforts
to obtain the forecasts from the office of issue. If the forecast is still not received, a
provisional forecast shall be prepared by that office and included in the
documentation. The aviation meteorological office shall inform the flight crew that
the forecast is provisional and the fact shall be recorded in the aerodrome forecast
form.
 The aerodrome forecast included in all documentation in tabular or cross section form
shall be in the abbreviated plain language form. Those included in chart form of
documentation may be either in the abbreviated plain language form or in TAF code
form.

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 Chapter - 8
ACTION FOR VIP/VVIP FLIGHT MOVEMENT

8.1 CONSIDERATION OF VIP/VVIP FLIGHTS

A non-scheduled flight by chartered or IAF aircraft arranged by the Government for any
important person and details of which are notified to the IMD by the DG of Civil Aviation,
Air HQ, the Protocol Division of the External Affairs Ministry, the Ministry of Civil
Aviation etc., may be considered as a VIP flight.
The term VVIP is used for President, Vice-President, Prime Minister and Deputy
Prime Minister of India as well as the Heads of States and Prime Ministers of foreign
countries.
Messages dealing with the programmes of such dignitaries should be prefixed with the
term “VVIP”, but the actual identity of the party should not be indicated in the messages.
Similarly the identity of the party should not be indicated in VIP messages also.
8.2 RESPONSIBILITY OF THE METEOROLOGICAL DEPARTMENT/OFFICE
 Necessary Meteorological services will be rendered by the MWO/AMO/AMS located
at the respective aerodrome.
 At aerodromes where no meteorological unit is available, special facilities by way of
current weather observations, briefing and documentation is to be provided, if the Civil
Aviation Department makes corresponding arrangements for ATC and
Communication (COM) facilities.
 The Regional Meteorological Centers concerned should liaise closely with the
Regional Controller of Aerodromes and Regional Controller of Communication to find
out if arrangements for providing ATC/COM facilities are being made and then
arrange for provision of meteorological facilities accordingly.
 If no arrangements are made by Airport Authority of India (AAI), IMD also need not
make any special arrangements.
 For reaching remote airfields, the AAI sometimes organize a service party consisting
of ATC and communication officers. The DDGM (RMC) concerned may attach the
IMD personnel to the service party for the sake of convenience.
 In case of inadequate notice, if it is not possible to make any arrangement for providing
meteorological facilities to VIP/VVIP flights, no arrangements may be made for the
same. In such cases the Collectors concerned may be informed about the weather
conditions on telephone/fax or e-mail. Acknowledgement of them having received the
message shall be obtained.
 If the VIP flight starts or terminates at an IAF air field, it is the responsibility of the
Air H. Q. to provide all facilities including the meteorological services. IMD need to

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 provide necessary service only on request from Air H. Q. (Directorate of Meteorology)
depending upon the communication facilities provided either by Air H.Q., or AAI.
Request to India Meteorological Department for rendering meteorological services in
connection with VIP/VVIP flights at IAF aerodromes (with or without meteorological
units) should come from Air H.Q. New Delhi. In special cases, request from local IAF
authorities for provision of Meteorological facilities may be entertained; provided IAF
agrees to place necessary facilities like transport, etc, at the disposal of the visiting IMD
officials.
Helicopter flights, at stations where no meteorological offices exist, need not be covered
unless AAI makes special arrangements for providing ATC/ COM facilities.
8.3 ACTION ON VIP/VVIP FLIGHT PROGRAMMES
8.3.1 Intimations
1. Intimations regarding VVIP/VIP flights are generally received from Air Headquarters,
Director General of Civil Aviation, Ministry of External Affairs etc., by the
meteorological office at Delhi (Palam) airport.
2. On receipt of intimation of a projected VIP/VVIP flight, AMO Delhi (Palam) should
sent a copy of the same to the concerned MWO /DDGM (RMC) and CAMD by
available fastest mode of communication.
3. Messages relating to VIP/VVIP movements in boarder areas should be exchanged by
AMSS, or Landline. As a routine, an acknowledgement of the message shall be send
by the in- charge of the receiving office to the originating office in all communications
made with respect to VIP/ VVIP flights.
4. Clarifications, if any, required by receiving office may be addressed direct to AMO
Delhi (Palam), who should consult with the authorities concerned and promptly issue
the clarifications required.
5. Intimations regarding VIP/VVIP flights received at a Met. Office other than at New
Delhi should be transmitted by that office to the concerned MWO/DDGM (RMCs) for
necessary instructions. CAMD, AMO Delhi (Palam) and DGM may be kept informed.
8.3.2 Briefing of VVIP flights
1. At all aerodromes where a forecasting office is functioning, briefing for VVIP flights
should be provided by the Meteorologist-in-charge or, in his absence on leave, tour
etc., by the Senior-most officer at the station.
2. Forecasts for VVIP flights whether originating at the station where an Aerodrome
Meteorological Office is located or elsewhere in the area of its jurisdiction should,
invariably, be issued in consultation with the in-charge of the Aerodrome
Meteorological Offices. The forecasts should be kept under constant review and
amendments should be issued promptly as and when necessary.

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 3. Full details of what is told to the pilots of VVIP flights by the briefing officers at the
time of briefing should be entered in the column ‘Briefing Notes’ of the briefing
register
8.3.3 Arrangements to be made by the RMC
As soon as the intimation is received regarding the programme of VIP/VVIP flight, the
RMCs should make the following arrangements:
1. The concerned MWO/AMO/AMS Met office should be alerted.
2. If there are no suitable meteorological staff available at the aerodrome of departure for
a flight, a Group A officer or an experienced Assistant Meteorologist if a Group A
officer cannot be spared, should be deputed for providing briefing and documentation,
provided AAI makes the corresponding arrangements as envisaged in para 7.2. This
officer should reach the station a day before the flight, if possible, for covering the
same.
3. If there is an AMS at the aerodrome of departure, manned by Assistant Meteorologist
possessing the requisite experience, briefing and documentation may be done by him.
Every effort should be made to send a gazetted officer on tour, if time permits, to
provide briefing and documentation for VIP flights, at an AMS manned by a Scientific
Assistant.
4. Special efforts are to be made to obtain the latest METAR and TAF of the destination
aerodrome and the designated alternate. If VVIP/VIP flight goes to a place where there
is no meteorological office, a gazetted officer or an experienced Assistant
Meteorologist may be sent on tour with portable instruments to provide the necessary
Current Weather observations (Local Routine and Local special) required. The
documentation and briefing may be provided, if, suitable communication facilities are
available to receive the same from the associated AMO. The above arrangement may
be done only if AAI authorities are making special arrangements for communication
at the station concerned.
5. In the case of VVIP flights to unmanned aerodromes, ATC and communication
facilities are normally provided. A gazetted officer /an experienced Assistant
Meteorologist should be deputed to cover VVIP flights to such aerodromes.
6. At Intermediate halts, where Aerodrome Meteorological Offices exist, generally fresh
briefing and documentation need be provided only if the halt at such places exceeds
45 minutes. For flights with the halts of shorter duration, through forecast from the
departure aerodrome to the final aerodrome of landing should be provided with an
outlook of weather from the destination aerodrome to a designated alternate.
7. At Intermediate halts without Aerodrome Meteorological Offices, fresh briefing and
documentation need be provided only if the halt exceeds 3 hours at the station. In such
cases, the required forecast should be sent to the concerned station sufficiently in time
to enable it been decoded and documentation to be provided before the departure of
the flight from the station.

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 8. Fresh briefing and documentation are to be provided at intermediate halts where there
is no AMO even if the halt is less than three hours in the case of (I) VVIP flight, (II)
in case where a number of aircraft are involved (e.g.: visits by Heads of Foreign
Governments).
9. In all cases whether fresh briefing and documentation are provided or not,
arrangements for current weather watch should be made to cover the arrival and
departure of the flights and for the reception of Current Weather observations of the
en-route stations, next halt and destination and alternates. These should be passed to
the Captain of the aircraft.
10. Current Weather reports of IAF stations connected by AFTN or meteorological T/P
channel may be obtained by these channels. TAFs of IAF stations having a forecasting
office may be obtained on AFTN or T/P channel if available at the station. Otherwise,
the TAFs may be originated by the Aerodrome Meteorological Office in whose area
the IAF station is located.
8.3.4 Provision of facilities for VVIP Flight
All meteorological facilities provided for a scheduled flight should be provided for
VIP/VVIP flights. The facilities provided are as follows:
1. An official going on tour to an aerodrome to provide meteorological facilities for
VIP/VVIP flights should carry with him an altimeter, a portable wind vane and a
portable anemometer and psychrometer, if no meteorological unit is available at the
aerodrome.
2. On arrival at the aerodrome, the officer must familiarise himself with the topography
in the vicinity of the aerodrome as quickly as possible. In case there is already a met
unit at the place, he should arrange with the local met staff for the current weather
observations required in connection with the flight. If there is no met unit, he should
himself plan the method of taking non-instrumental observations, like, visibility,
cloud height etc. He should contact AAI and if necessary, other local authorities, such
as, Collector, Revenue or Police Officials etc., and make suitable arrangements for
expeditious reception and dispatch of met messages and for necessary facilities.
3. The Met. Unit (already existing or the one temporarily set up for the purpose of the
VIP/VVIP flight in question) serving the aerodrome of arrival should supply hourly/
half hourly METAR /SPECI messages, if any, to the aerodrome of departure
commencing at least two hours before ETD, by all available departmental
communication channels.
4. After take-off of the flight from the previous station, hourly or half hourly current
weather messages should be supplied as necessary, to the local ATC till the plane
arrives at the station. Just before landing, all operational meteorological information
required for landing should be supplied.
5. All or part of these messages should be sent to the AMO who will issue the forecast
for the flight.

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 6. All these messages should also be sent to the MWO concerned, when required.
7. After arrival of the plane, the pilot should be de-briefed if feasible. The de-briefing
report may be immediately transmitted to the associated AMO as per prior
instructions. Otherwise, the same may be submitted to the associated A.M.O along
with other documents concerning the flight. If, however, the de-briefing report
contains such vital information which in the opinion of the de-briefing officer is
necessary to be immediately communicated to the associated AMO he should do so,
even in the absence of such instructions.
8. Pre-flight planning information as is available at the station or obtaining the same
expeditiously from the associated AMO concerned, should be supplied whenever
required.
9. If there is an AMS at the aerodrome of departure, it is the responsibility of the AMS
to decode the ROFOR and TAFs and other information received from the associated
AMO and provide the necessary briefing and documentation. The efforts made to get
the above reports should be entered in briefing register. The forms used for
documentation should be the same as for scheduled flights.
10. Briefing should be done with the help of current weather reports and any analyses,
inferences etc., received from the associated AMO.
11. Current weather reports along with other relevant information available, of destination
and alternates will be passed on to ATC till the aircraft lands.
12. Soon after the conclusion of VVIP/VIP flight, the officer deputed should submit a
report regarding the action taken by him and also indicate the shortcomings
experienced by him. He should also indicate the type of discussions he had with the
crew of VIP/VVIP flight or other authorities
8.3.5 Responsibility of Associated AMO
The associated AMO will send whenever necessary ROFORs/ TAFs and SIGMET to the
office providing briefing and documentation by all communication channels available at
its disposal so as to reach well in advance for rendering adequate met service. If such
information is to be received from other offices the associated A.M.O. should arrange for
the receipt for the required information by sending suitable requisitions. Arrangements
for expeditious reception of C.W. observations of relevant stations should be made. The
associated A.M.O should intimate in advance the concerned station of the arrangement.
8.3.6 Responsibility of MWO
Area meteorological watch will be maintained as usual in the FIR of jurisdiction. The
M.W.O should ensure that SIGMET information of interest to the flight is passed to the
aircraft through the appropriate A.T.C. channels.
8.3.7 Responsibility of RCs after the flight
On receipt of the report as envisaged in para above the DDGM (RMC) should satisfy
himself that the officer concerned had rendered the meteorological facilities satisfactorily.

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 Any important points mentioned in the report such as, difficulties experienced by the
officer, may be communicated to CAMD, who if necessary may bring to the notice of
DGM with suitable remarks.
8.3.8 Retention of documents
1. Copies of documents supplied to VVIP/VIP flights should be collected at RMC/MWO
and preserved for a period of 180 days as in the case of other documents.
2. These instructions do not apply to flights of VIPs by scheduled services. No special
arrangement need be made for such flights.
3. If VIP/VVIP flight crew do not turn up either for collection of forecast or for briefing,
entries may be made to that effect in the briefing register. Such instances may also be
brought to the notice of CAMD New Delhi.

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 Chapter - 9
ONLINE BRIEFING SYSTEM (OLBS)

9.1 OLBS updating procedure and time schedule for update

Online Met Briefing System (OLBS) provides weather information to pilots,
dispatchers and air traffic controllers to support flight safety and efficiency. It provides
a crucial service to the national and international civil aviation sector in fulfilment of
the requirements prescribed by the International Civil Aviation Organisation (ICAO)
and the Director General of Civil Aviation of India (DGCA). Officers and staff make
their best efforts to provide authentic and usable products by updating contents in the
OLBS.
9.2 OLBS Server Design:
OLBS Server is a combination of a Message Handler and a Web Server. It is connected
to the WMAN communication server through a GTS socket stream and handles
messages. Hence it receives global aviation data and products through WMAN. The
web-server provides web pages for online Met Briefing as well as data input pages to
input METAR/TAF etc., by other Met Offices. All products are either automatically
uploaded on receipt from WMAN or product generator upload using web-pages.

The products uploaded in OLBS can be classified as 1. Scheduled products, which are to
be uploaded and made available always and 2. Non-scheduled products are uploaded as
and when the products are generated by the issuing offices. All timings are in UTC.

1. Scheduled Products: These products are uploaded at fixed timings as per the
observation schedule or issue schedule.
i. METAR,
ii. Take-off Data,
iii. TAF,

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 iv. Area Forecast,
v. WAFC Wind/Temp,
vi. IMD Wind Temp Charts,
vii. WAFC SigWx Charts,
viii. IMD SigWx Charts,
ix. Radar Pictures,
x. SAT images,
xi. IWB,
xii. Regional Inferences and
xiii. IONASAC Bulletins are the Scheduled Products. Availability of these products
are to be monitored at regular intervals.
i. METAR:
Originator: AMS and AMOs
Time of Issue: HH00, HH30
Mode of collection and upload: At HH03, HH33 by WMAN and OLBS MHS
Tools to Check National METARs: OLBS  ObservationsMETAR
Action for missing product:
a) Collect from the Originator
b) Retrieve from VABBYZYX
International METARs: Retrieve from
REGIONAL OPMET DATA BANKS RJTDYZYX, VTBBYZYX, YBBBYZYX,
NFFNYZYX, WSSSYZYX
ii. Take-off Data:
Originator: AMO
Time of Issue: 0030, 0330, 0630, 0930, 1230, 1530, 1830
Mode of collection and upload: OLBS MHS
Tools to Check: OLBS  ObservationsForecastsTake-off
Action for missing product: Collect from the Originator
iii. TAF:
Originator: AMO
Time of Issue: a. Short TAF – 0200, 0500,0800,1100,1400,1700,2000,2300
b. Log TAF – 0500, 1100, 1700, 2300
Mode of collection and upload: WMAN, OLBS MHS and OLBS Web Form

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Tools to Check National TAFs: OLBS  forecastsLong TAF/Short TAF:
Action for missing product:
a) Collect from the Originator
b) Retrieve from VABBYZYX
International TAFs: Retrieve from
REGIONAL OPMET DATA BANKS RJTDYZYX, VTBBYZYX, YBBBYZYX,
NFFNYZYX, WSSSYZYX
iv. Area Forecast:
Originator: AMO
Time of Issue: 0530, 1330 and 2130
Mode of collection and upload: OLBS Web Form
Tools to Check: OLBS  forecastsArea Forecast
Action for missing product: Inform the Originator
v. WAFC Wind Temp Charts:
Originator: EGRR WAFC London
Time of Download of GRIB2: Based on 00  0401, 06  1001, 12  1601,
182201
Mode of collection: SADIS FTP
Tools to Check: MHS DATA MONITORING
Action for missing product:
a) Check WAFC Notices
b) Run the FTP script manually
c) In case WAFC London EGRR GRIB2 non-availability, fetch GRIB2 from WAFC
KWBC
Time of Chart Generation: 0430,1030,1630,2230
Mode of Preparation: OLBS Chart Generation Software
Tools to Check: MHS DATA MONITORING
Action for missing product:
a) Check WAFC Notices
b) Run the chart generation script manually
vi. IMD Wind Temp Charts:
Originator: NWP, New Delhi
Time of Download: Based on 00  0712, 06  1312, 12  1912, 180112

101
Mode of collection and upload: FTP
Tools to Check: MHS DATA MONITORING
Action for missing product: Run the FTP script manually
vii. WAFC SIGWX Charts:
Originator: EGRR WAFC London
Time of Download of BUFR: Based on 00  0901, 06  1501, 12  2101, 180301
Mode of collection: SADIS FTP
Tools to Check: MHS DATA MONITORING
Action for missing product:
a) Check WAFC Notices
b) Run the FTP script manually
c) In case WAFC London EGRR BUFR non-availability, fetch from WAFC KWBC
Time of Chart Generation: 0910,1510,2110,0310
Mode of Preparation: OLBS Chart Generation Software
Tools to Check: MHS DATA MONITORING
Action for missing product:
a) Check WAFC Notices
b) Run the chart generation script manually
viii. IMD SIGWX Charts:
Originator: MWO Chennai
Time of Issue: Based on 00  0901, 06  1501, 12  2101, 180301
Mode of collection and upload: FTP from DO PC to OLBS
Tools to Check: MHS DATA MONITORING
Action for missing product: Run the FTP script manually
ix. Radar Pictures:
Originator: DWR Stations
Time Of Issue: Every 10 minutes
Mode of collection and upload: FTP
Tools to Check: MHS DATA MONITORING
Action for missing product: Contact concerned DWR
x. SAT Images:
Originator: SAT Met, New Delhi

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Time of Issue: Every 30 Mts
Mode of collection and upload: FTP
Tools to Check: MHS DATA MONITORING
Action for missing product: SAT Met, New Delhi
xi. IWB:
Originator: IMD, Pune
Time of Issue: Based on 0300UTC and 1200UTC
Mode of collection and upload: WMCC (AMSS) through RTH New Delhi
Tools to Check: Online
Action for missing product: RTH New Delhi
xii. Regional Inferences:
Originator: RMC
Time of Issue: Based on 0300Utc and 1200UTC
Mode of collection and upload: WMCC (AMSS)
Tools to Check: Online
Action for missing product: Contact respective RMCs
xiii. IONOSAC Bulletins:
Originator: IONOSAC Section, IMD, Pune
Time of Issue Based on 0000UTC and 1200UTC
Mode of collection and upload: WMCC (AMSS)
Tools to Check: Online
Action for missing product: contact IONOSAC Section, IMD, Pune
2. Non-Scheduled Products: These products are generated by Offices whenever
certain weather phenomena occur in the area concerned. They are i. Aerodrome
Warning, ii. SIGMET iii. Tropical Cyclone Advisories.
i. Aerodrome Warning:
Originator: AMO
Mode of collection and upload: OLBS WEB form
Tools to Check: OLBS  forecastsAerodrome Warning
Action for missing product: Contact the concerned AMO
ii. SIGMET:
Originator: MWO
Mode of collection and upload: WMAN

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Tools to Check: OLBS  forecastsSIGMET
Action for missing product: Resubmit at WMAN
iii. Tropical Cyclone Advisories:
Originator: TCAC, New Delhi
Mode of collection and upload: Received through Email and uploaded using Graphical
Tropical Cyclone Advisory
Tools to Check: OLBS  Forecasts Graphical Tropical Cyclone Advisory
Action for missing product: Repeat Upload procedure.
Action on Messages from Users Requesting products:
Users are provided with a facility to send messages through OLBS whenever a
required real time product is not available in the web-site. OLBS staff shall monitor
such messages and update the requested product.
OLBS Product Schedules:
Short TAF Schedule:
Validity Issue Time/Upload Time
00-09 2300
03-12 0200
06-15 0500
09-18 0800
12-21 1100
15-24 1400
18-03 1700
21-06 2000

Long TAF Schedule:

Validity Issue Time/Upload Time
00-06 2300
06-12 0500
12-18 1100
18-24 1700

Take-Off Data Schedule:

Validity Issue Time/Upload Time
0100-0600 0030
0400-0900 0330
0700-1200 0630
1000-1500 0930

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 1300-1800 1230
1600-2100 1530
1900-2400 1830

Area forecast Schedule:

Validity Issue Time/Upload Time
0600-1400 0530
1400-2200 1330
2200-0600 2130

WAFC GRIB2 download Schedule:

Data time Download beginning Time
0000 0401 *
0600 1001*
1200 1601*
1800 2201*

(*Download begins 0401 hrs from the time of observation) WAFC W/T Charts
Generation Schedule:
Data time Generation Time/Upload Time
0000 0430
0600 1030
1200 1630
1800 2230

WAFC BUFR Download Schedule

Data time Download Time
0000 0901*
0600 1501 *
1200 2101 *
1800 0301 *

(* Download begins 0901 hrs from the time of observation)

WAFC SIGWX CHART Generation Schedule:
Data time Chart Generation Time/Upload Time
0000 0910
0600 1510
1200 2110
1800 0310

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 IMD W/T Carts Schedule:
Validity Upload Time
Data time 0000 0712
Data time 0600 1312
Data time 1200 1912
Data time 1800 0112

IMD SIGWX Charts Schedule:

Based on Issue Time/Upload Time
0000 0900
0600 1500
1200 2100
1800 0300

9.3 REGISTRATION PROCEDURE TO OLBS FOR STAKEHOLDERS

Online Met Briefing System (OLBS) is a web-based pre-flight information briefing
system provided by India Meteorological Department for flights originating from
airports in India. The system is operational since 1st December 2012 with servers in
Chennai and Delhi. As per DGCA Regulations, only authorized Pilots/Flight
Dispatchers can avail Met. Briefing. Users are required to register themselves online
in OLBS for availing the services. There are around 1400 registered users. The users
can be classified as i. IMD Offices ii. DGCA and iii. Flight Operators.
Registration of IMD Offices and DGCA:
IMD Offices require access to OLBS to provide Met briefing for Non-scheduled
flights and VIP/VVIP flights. DGCA requires access to OLBS as a regulatory body in
the field of Civil Aviation. OLBS system administrator shall submit the details of the
IMD Offices and DGCA and the system generates. The username and password shall
be informed to the corresponding offices by email.
Procedure for registration of Flight Operators is given below:
Information about OLBS: The airlines get the information about OLBS through Met
Offices in the airports or through IMD Website. URL for Registration:
https://olbs.amsschennai.gov.in for Chennai site and https://olbs.amssdelhi.gov.in for
Delhi site.
Formation of Club: (Club administrator):
Airlines with many Pilots and Flight Despatchers are registered as a ‘Club’. For each
registered club an administrator is designated in consultation with the Head of the
Airlines. The OLBS admin collects the required information and creates Clubs. It is
the responsibility of the Club administrator to check the genuineness of the users under
the club.
Registration shall be initiated by the applicants by clicking the link ‘Click here to
register’ or the button ‘Register’ found in the web page. The applicant is navigated to
a page containing FAQ and terms and conditions. On clicking the button ‘continue’
found at the bottom of this page, the online registration form appears.

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The following details are to be furnished by the applicant in the registration form:
Email address
Requested username
Full name(s)
Telephone number
Physical address
Company/Organization
Motivation and Pilot License No. / DGCA Flight Dispatcher No
FD/CPL/ATPL Number
FD/CPL/ATPL Expiry Date
Airline Operator (Drop down menu to select the name of the club or none)

The applicant belonging to a registered club shall select the name of the appropriate
club under item No.10. Airline Operator else select ‘None’. The applicant shall
submit the details by clicking the button ‘Register’ found at the bottom of the form
page.
OLBS Automated Response:
1. The system validates the details and originates verification emails to the applicant
to his email ID and to the club administrator, if the applicant belongs to a registered
club.
2. The system displays the details of the application in the User Management Page
under Pending Activation.
Expected Response from the applicant and club administrator:
1. The applicant shall click the activation link received from the OLBS system.
2. The club administrator shall either approve or disapprove the applicant through the
email sent by OLBS.
Authorization Procedure:

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The OLBS admin shall regularly check the User Management Page for requests
pending for approval and process the requests.
Applicants belonging to a Club:
‘Approve’ if the approval from the club admin approval is ‘YES’ and the applicant
verification is “YES”.
The System sends an email to the applicant informing the username/password. The
password can be changed by the user at any time after registration.
‘Reject’ the application if the club administrator approval is ‘NO’.
Keep pending and generate email reminders to the parties until a response is received.
Applicants not belonging to a Club:
1. The OLBS admin shall check the details provided by the applicant and the
entry under club is N/A.
2. Shall check whether the applicant has verified the system sent email. If ‘No’
generate an email reminder to verify the system sent email.
3. If the applicant’s verification is ‘YES’, request further details to be
furnished through the official email ID of the OLBS station.
4. Instruct the applicant to send to the OLBS station official email ID
5. Scanned copy of the valid license
Flight levels of operation
Frequency of operation
Authorization letter from the Company CEO.
Shall ‘Approve’ if the flight level of operation is Medium/High altitude and the other
documents are found valid and genuine.
The System sends an email to the applicant informing the username/password. The
password can be changed by the user at any time after registration.
Shall ‘Reject’ if the flight level of operation is Low altitude and originate an email
informing rejection with the reason.
Shall ‘Reject’ if the applicant’s license is not valid and the request is not genuine and
originate an email informing rejection with the reason.
The system removes the entries of applicant from the User Management Page on
‘Approval’ or ‘Rejection’. The system also posts a message to OLBS administrator.
Replication of Registration: Once an user is approved and registered in one of the
OLBS viz Chennai or Delhi relevant entries are made in the other OLBS enabling the
user access both the systems with the same username/password.
Blocking A Registered User: In the event of a registered user misuse/exploit the
access to the OLBS the login shall be blocked and the user shall be informed. The
registration shall be cancelled on receipt of information regarding
termination/resignation of a registered operator from the company.

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 Chapter - 10
OPERATIONAL MESSAGES

10.1 INTRODUCTION
India Meteorological Department caters to the needs of Aviation Services through a
network of 4 Meteorological Watch Offices (MWOs – Kolkata, Delhi, Chennai and
Mumbai), 18 Aerodrome Meteorological Offices (including 4 MWOs) and 54
Aeronautical meteorological stations (AMS). The operational messages managed by
all the offices and stations are given below:
Type of offices Operational Messages WMO Heading
Disseminated
TTAAiiCCCC
for National Transmission
METAR SAIN90 CCCC
SPECI SPIN90 CCCC
Long TAF FTIN90 CCCC
MWOs Short TAF FCIN90 CCCC
WS SIGMET WSIN31 CCCC
VA SIGMET WVIN31 CCCC
TC SIGMET WCIN31 CCCC
METAR SAIN90 CCCC
AMOs SPECI SPIN90 CCCC
Long TAF FTIN90 CCCC
Short TAF FCIN90 CCCC
AMSs METAR SAIN90 CCCC
SPECI SPIN90 CCCC
Except the above mentioned operational messages there are also some other
operational messages managed by different Met offices which is discussed below.
10.2 EXAMPLES OF OPERATIONAL MESSAGES
METAR
METAR VECC 032100Z 28003KT 4000 HZ SCT020 BKN100 25/23 Q1008
TEMPO 3000 HZ
MET REPORT VECC 032110Z WIND 280/3KT VIS 4000M HZ CLD SCT 2000FT
(600M) BKN 10000FT (3000M) T25 DP23 QNH 1008HPA TREND TEMPO VIS
3000MHZ
Meaning:
Local routine weather report for Kolkata airport issued on 3rd of the month at 2100
UTC, surface wind direction 280 degrees and wind speed 3 knots, visibility 4000
metres, present weather is Haze, scattered clouds at 2000 feet (600 metres) and broken
clouds at 10000 feet (3000 metres), air temperature 25℃ , dew point temperature 23℃,
QNH 1008 hPa, Trend during next 2 hours is temporary reduction of visibility to 3000
metres in Haze.
SPECI (For reduction invisibility)

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SPECI VECC 032216Z 00000KT 3000 HZ SCT020 BKN100 24/23 Q1007 TEMPO
2000 BR
SPECIAL VECC 032216Z WIND CALM VIS 3000M HZ CLD SCT 2000FT (600M)
BKN 10000FT (3000M) T24 DP23 QNH 1007HPA TREND TEMPO VIS 2000M
BR
Meaning:
Local special weather report for Kolkata airport issued on 3rd of the month at 2216
UTC, surface wind calm, visibility 3000 metres, present weather is Haze, scattered
clouds at 2000 feet (600 metres) and broken clouds at 10000 feet, air temperature
24℃, dew point temperature 23℃, QNH 1007 hPa, Trend during next 2 hours is
visibility reducing to 2000 metres for a period of less than one hour in Mist.
ADDITIONAL (For reduction of visibility to 2000m)
Coded form not given as ADDITIONAL is meant for local use only.
ADDITIONAL VECC 032314Z WIND CALM VIS 2000M BR CLD SCT 2000FT
(600M) BKN 10000FT (3000M) T23 DP23 QNH 1008HPA TREND NOSIG
Meaning:
Local additional weather report for Kolkata airport issued on 3rd of the month at 2314
UTC, surface wind calm, visibility 2000 metres, present weather is Mist, few clouds
at 2000 feet (600 metres) and broken clouds at 10000 feet (3000 metres), air
temperature 23℃, dew point temperature 23℃, QNH 1008 hPa, Trend during next 2
hours is no significant change.
TAF (LONG TAF)
TAF VECC 041100Z 0412/0518 15006KT 3000 HZ SCT018 BKN 100 BECMG
0418/0420 00000KT 2200 –RA BR BECMG 0500/0502 1000 BR FEW020 SCT100
BECMG 0503/00505 11005KT 2200 HZ BECMG 0506/0508 17007KT 3200 HZ
SCT018 SCT100 TEMPO 0512/0514 2000 TSRA SCT015 FEW025CB OVC090
Meaning:
Terminal Aerodrome Forecast issued by Kolkata airport on 4th day of the month at
1100 UTC with validity period of 30 hours ranging from 1200 UTC of that day to
1800 UTC of the next day. The general forecasting consist of surface wind direction
150 degree and surface wind speed 06 knots, visibility 3000 metres in present weather
Haze, scattered clouds at 1800 feet (540 metres) and broken clouds at 10000 feet (3000
metres).
It is expected that the surface wind will gradually become calm within the period
1800 UTC and 2000 UTC; similarly visibility will likely to reduce to 2200 metres
either in light rain or in Mist within that period.
It is expected that the visibility will likely to reduce to 1000 metres in Mist within the
period 0000 UTC and 0200 UTC of the next day; few clouds at 2000 feet (600 metres)
and scattered clouds at 10000 feet (3000 metres).

110
It is expected that the surface wind direction will 110 degree and surface wind speed
will 05 knots within the period 0300 UTC and 0500 UTC of the next day; visibility
will likely to increase to 2200 metres in Haze within that period.
It is expected that the surface wind direction will 170 degree and surface wind speed
will 07 knots within the period 0600 UTC and 0800 UTC of the next day; visibility
will likely to increase to 3200 metres in Haze within that period; scattered clouds at
1800 feet (540 metres) and scattered clouds at 10000 feet (3000 metres).
It is expected that the visibility will temporarily reduce to 2000 metres in present
weather thunderstorm within the period 1200 UTC and 1400 UTC; scattered clouds
at 1500 feet (450 metres), few cumulonimbus clouds at 2500 feet (750 metres),
overcast clouds at 9000 feet (2700 metres).
TAF (SHORT TAF)
TAF VECC 041100Z 0412/0421 15006KT 3000 HZ SCT018 BKN 100 BECMG
0418/0420 00000KT 2200 –RA BR
Meaning:
Terminal Aerodrome Forecast issued by Kolkata airport on 4th day of the month at
1100 UTC with validity period of 9 hours ranging from 1200 UTC to 2100 UTC. The
general forecasting consist of surface wind direction 150 degree and surface wind
speed 06 knots, visibility 3000 metres in present weather Haze, scattered clouds at
1800 feet (540 metres) and broken clouds at 10000 feet (3000 metres).
It is expected that the surface wind will gradually become calm within the period 1800
UTC and 2000 UTC; similarly visibility will likely to reduce to 2200 metres either in
Light Rain or in Mist within that period.
AERODROME WARNING
VECC 201200Z AD WRNG 3 VALID 201320/201520 SFC WSPD 40KT MAX
60KT FROM 050 DEG TSRA FCST NC=
Meaning:
Aerodrome warning number 3issued by Kolkata airport at 1200 UTC on 20 th day of
the month with validity period of 2 hours from 1320 UTC to 1520 UTC. It is
forecasted that the surface wind speed will reach 40 knots gusting to 60 knots from 50
degree in Thunderstorm. No change of intensity is expected.
LIGHT AIRCRAFT WARNING
VECC 250600Z LIGHT AIRCRAFT WRNG 2 VALID 250630/250930 SFC
WDSPD 17KT MAX 27 KT FROM 190 DEG FCST NC=
Meaning:
Light Aircraft warning number 2issued by Kolkata airport at 0600 UTC on 25th day
of the month with validity period of 3 hours from 0630 UTC to 0930 UTC. It is
forecasted that the surface wind speed will reach 17 knots gusting to 27 knots from
190 degree. No change of intensity is expected.

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OUTLOOK (LOW VISIBILITY PROCEDURE)

Meaning:
Outlook for low visibility is issued by Kolkata airport at 0115 UTC on 05th December,
2019 as visibility reduces to 1000 metres. RVR of runway 01R touchdown zone is
1100 metres; RVR of runway 01R mid is 1000 metres. RVR of runway 19L
touchdown zone is 1100 metres; RVR of runway 19L mid is 1000 metres. It is
expected that the visibility will likely reduce to 800 metres in Mist Fog.

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ADVISORY (LOW VISIBILITY PROCEDURE)

Meaning:
Advisory for low visibility is issued by Kolkata airport at 0118 UTC on 05th
December, 2019 as RVR is expected to fall below 800 metres. RVR of runway 01R
touchdown zone is 1000 metres; RVR of runway 01R mid is 1000 metres. RVR of
runway 19L touchdown zone is 1000 metres; RVR of runway 19L mid is 1000 metres.
It is expected that the visibility will likely reduce to 700 metres in Mist Fog.

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TC ADVISORY

Meaning:
Tropical cyclone advisory number 11 for tropical cyclone AMPHAN issued at 1200
UTC on 18 th May, 2020 by TCAC New Delhi. Position of the centre of the tropical
cyclone is 14°00´´ north, 86°18´´ east. Direction and speed of movement are
Northwards and 12 knots respectively. Central pressure is 930 hPa. Max surface wind
near the centre is 120 knots. Forecasted position of the centre of tropical cyclone after
6 hours (1800 UTC) is 15°12´´ North, 86°30´´ East with max surface wind speed 125
knots. Forecasted position of the centre of tropical cyclone after 12 hours (0000 UTC
of 19 th May, 2020) is 15°54´´ North, 86°42´´ East with max surface wind speed 125
knots. Forecasted position of the centre of tropical cyclone after 18 hours (0600 UTC
of 19 th May, 2020) is 17°06´´ North, 87°00´´ East with max surface wind speed 125
knots. Forecasted position of the centre of tropical cyclone after 24 hours (1200 UTC
of 19 th May, 2020) is 17°42´´ North, 87°12´´ East with max surface wind speed 120
knots. Next advisory message will be issued on 2100 UTC of 18 th May, 2020.

TC SIGMET
VECF SIGMET 1 VALID 190600/191200 VECC – VECF KOLKATA FIR TC
AMPHAN OBS AT 0000Z N1536 E08642 CB TOP FL 520 WI 200 NM OF
CENTRE MOV NNE 12KT NC FCST 1200Z TC CENTRE N1724 E08706
Meaning:
SIGMET 1 valid from 190600 UTC to 191200 UTC issued by MWO Kolkata for
Kolkata FIR for Tropical Cyclone AMPHAN observed at 15º36´´ North and 86
º42´´East, CB top at flight level 52000 feet within 200 nautical mile of centre
movement NNE, expected no change of intensity, forecasted at 1200Z TC centre will
be at 17º24´´ North and 87º06´´ East.

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 Chapter-11
WORLD AREA FORECAST SYSTEM

11.1 INTRODUCTION
The objective of the World Area Forecast System is to supply meteorological authorities
and other users with global aeronautical meteorological en-route forecasts in digital form.
This objective is achieved through a comprehensive, integrated, worldwide and, as far as
practicable, uniform system, and in a cost effective manner, taking full advantage of
evolving technologies.
11.2 WORLD AREA FORECAST CENTRES (WAFC)
Responsibilities of WAFC:
a. To prepare gridded global forecast of
1. upper wind;
2. upper air temperature and humidity;
3. Geopotential altitude of flight levels;
4. flight level and temperature of tropopause;
5. direction, speed and flight level of maximum wind;
6. cumulonimbus clouds;
7. icing; and
8. turbulence;
b. To prepare global forecasts of significant weather(SIGWX) phenomena
c. To issue the forecasts referred to in a) and b) in digital form to meteorological
authorities and other users.
d. To receive information concerning the accidental release of radioactive materials into
the atmosphere from its associated WMO Regional Specialised Meteorological Centre
(RSMC) for the provision of transport model products for radiological environmental
emergency response, in order to include the information in significant weather
forecasts; and
e. To establish and maintain contact with VAACs for the exchange of information on
volcanic activity in order to coordinate the inclusion of information on volcanic
eruptions in significant weather forecasts.

The forecasts of upper wind; upper-air temperature; and humidity; direction, speed and
flight level of maximum wind; flight level and temperature of tropopause, areas of
cumulonimbus clouds, icing, clear-air and in-cloud turbulence, and Geopotential altitude
of flight levels will be prepared four times a day by the WAFC and will be valid for fixed
115
valid times at 6, 9, 12, 15, 18, 21, 24, 27, 30, 33 and 36 hours after the time (0000, 0600,
1200 and 1800 UTC) of the synoptic data on which the forecasts were based. The
dissemination of each forecast shall be in the above order and will be completed as soon
as technically feasible, as but not later than 6 hours after standard time of observation.

The grid point forecasts prepared by a WAFC comprise:

a) Wind and temperature data for flight levels 50 (850 hPa), 100 (700 hPa), 140 (600
hPa), 180 (500 hPa), 240 (400 hPa), 270 (350hPa), 300 (300 hPa), 320 (275 hPa), 340
(250 hPa), 360 (225hPa), 390 (200 hPa), 450 (150 hPa) and 530 (100 hPa);
b) Flight level and temperature of tropopause;
c) Direction, speed and flight level of maximum wind;
d) Humidity data for flight levels 50 (850 hPa), 100 (700 hPa), 140 (600 hPa), and 180
(500 hPa);
e) Horizontal extent and flight levels of base and top of cumulonimbus clouds;
f) Icing for layers centered at flight levels 60 (800hPa), 100 (700hPa), 140 (600 hPa),
180 (500 hPa), 240 (400 hPa) and 300 (300 hPa);
g) Clear-air turbulence for layers centered at flight levels 240 (400 hPa), 270 (350 hPa),
300 (300 hPa), 340 (250 hPa), 390 (200 hPa) and 450 (150 hPa);
h) In-cloud turbulence for layers centered at flight levels 100 (700 hPa), 140 (600 hPa),
180 (500 hPa), 240 (400 hPa) and 300 (300 hPa); and
1) Note 1: Layers centered at a flight level referred to in (f) and (h) have a depth of
100 hPa.
2) Note 2: Layers centered at a flight level referred to in (g) have a depth of 50 hPa.
3) Note3: The products from e to h are issued on a trial basis and are available
through FTP service.
i) Geopotential altitude data for flight levels 50 (850 hPa), 100 (700 hPa), 140 (600 hPa),
180 (500 hPa), 240 (400 hPa), 300 (300 hPa), 320 (275 hPa), 340 (250 hPa), 360 (225
hPa), 390 (200 hPa), 450 (150 hPa) and 530 (100 hPa).

The above grid point forecasts are being issued by a WAFC in binary code form using the
GRIB code form prescribed by WMO. The grid point forecasts are prepared in a regular
grid with a horizontal resolution of 1.25° of latitude and longitude.

116
Fig: WAFC Wind/ Temp Charts at FL 140 and FL320

117
11.3 SIGNIFICANT WEATHER (SIGWX) FORECASTS
General provisions
Forecasts of significant en-route weather phenomena are being prepared as SIGWX
forecasts four times a day by WAFC. They are valid for fixed valid times at 24 hours after
the time (0000, 0600, 1200 and 1800 UTC) of the synoptic data on which the forecasts
were based. The dissemination of each forecast is completed as soon as technically
feasible, as but not later than 9 hours after standard time of observation.
SIGWX forecasts are issued in binary code form using the BUFR code form prescribed by
WMO.
Types of SIGWX forecasts
SIGWX forecasts are being issued as:
i) High- level forecasts for flight levels between 250 and 630; and
ii) Medium-level forecasts for flight levels between 100 and 250.

Items included in WAFC SIGWX forecasts

High-level and medium level forecasts of WAFC include the following items:
a. Tropical cyclone provided that the maximum of the 10-minute mean surface
wind speed is expected to reach or exceed 34 knots; severe squall lines;
b. Moderate or severe turbulence (in cloud or clear air);
c. Moderate or severe icing;
d. Widespread sand storm / duststorm;
e. Cumulonimbus cloud associated with thunderstorm and with a) to e);
Note: Non-convective cloud areas associated with in-cloud moderate or severe
turbulence and/or moderate or severe icing are to be included in SIGWX forecasts
f. Flight level of tropopause;
g. Jet streams;
h. Information on the location of volcanic eruptions that are producing ash clouds of
significance to aircraft operations comprising: volcanic eruption symbol at the location
of the volcano and, at the side of the chart, the volcano eruption symbol, the name of
the volcano, latitude/longitude, the date and time of first eruption, if known, and a
reference to SIGMET and NOTAM or ASHTAM issued for the area concerned; and
i. Information on the location of an accidental release of radioactive materials into the
atmosphere, of significance to aircraft operations, comprising: the radio activity symbol
at the site of the accident and, at the side of the chart, the radio activity symbol, latitude/
longitude of the site of the accident, date and time of the accident and a reminder to
users to check NOTAM for the area concerned.

Criteria for including items in WAFC SIGWX forecasts:

The following criteria are applied for SIGWX forecasts:
a. The abbreviation “CB” is included only when it refers to the occurrence or expected
118
 occurrence of cumulonimbus clouds:
1) Affecting an area with a maximum spatial coverage of 50% or more of the area
concerned;
2) Along a line with little or no space between individual clouds; or
3) Embedded in cloud layers or concealed by haze.
b. The inclusion of “CB” shall be understood to include all weather phenomena normally
associated with cumulonimbus clouds, i.e. thunderstorm, moderate or severe icing,
moderate or severe turbulence and hail;
c. where a volcanic eruption or an accidental release of radioactive materials into the
atmosphere warrants the inclusion of the volcanic activity symbol or the radioactivity
symbol in SIGWX forecasts, the symbols shall be included on SIGWX forecasts
irrespective of the height to which the ash column or radioactive material is reported
or expected to reach; and
d. In the case of co-incident or the partial overlapping of items a) [tropical cyclones], i)
[volcanic eruptions] and j) [accidental release of radioactive materials], the highest
priority is given to volcanic eruptions, followed by release of radioactive materials
and by tropical cyclones. The item with the highest priority is placed at the location of
the event, and an arrow is used to link the location of the other item(s) to its associated
symbol or textbox.

Fig: SIG WX Chart (FL 100 – FL 450)

119
Fig: SIGWX Chart (FL 250 – FL 630)

120
Fig: NATIONAL SIGWX Chart- MIDDLE LEVEL

121
Fig: NATIONAL SIGWX Chart- HIGH LEVEL

122
Weather Symbol:

123
Severe squall line symbol: In flight documentation for flights operating up to FL 100.
This symbol refers to “squall line”.
Radioactive materials in the atmosphere symbol: The following information shall be
included at the side of the chart: radioactive material symbol; latitude/longitude of the
accident site; date and time of accident; check NOTAM for further information.
Volcanic eruption symbol: The following information shall be included at the side of
the chart: volcanic eruption symbol; name an international number of volcano (if known);
latitude/longitude; date and time of the first eruption (if known); check SIGMETs and
NOTAM or ASHTAM for volcanic ash.
Freezing precipitation: This symbol does not refer to icing due to precipitation coming
into contact with an aircraft, which is at a very low temperature.
Visible ash cloud symbol: Visible ash cloud symbol applies only to model VAG not to
SIGWX charts.
NOTE: Height indications between which phenomena are expected, top above base as
per chart legend.
Abbreviations used to describe clouds:
Type
CI=Cirrus AS =Altostratus ST = Stratus
CC = Cirrocumulus NS = Nimbostratus CU = Cumulus
CS=Cirrostratus SC = Stratocumulus
CB= Cumulonimbus
AC =Altocumulus
Amount
Clouds except CB
SKC = sky clear (0/8) FEW = few (1/8 to2/8)
SCT = scattered (3/8 to 4/8) OVC = overcast (8/8)
CB only
ISOL = individual CBs (isolated)
OCNL = well-separated CBs (occasional)
FRQ = CBs with little or no separation (frequent)
EMBD= CBs embedded in layers of clouds or concealed by haze (embedded)
Height
Heights are indicating on SWH and SWM charts in flight levels (FL), top over base.

124
 When XXX is used, tops or bases are outside the layer of the atmosphere to which the
chart applies.
In SWL charts:
Heights are indicated as altitudes above mean sea level;
The abbreviation SFC is used to indicate ground level.
Depicting of lines and systems on specific charts
Models SWH and SWM – Significant weather charts (high and medium)
Scalloped line demarcation of areas of significant weather
Heavy broken line delineation of area of CAT
Heavy solid line Position of jet stream axis with indication of wind direction
position of jet stream axis with indication of wind direction,
Interrupted by wind arrow and flight level speed in kt and height in flight level. The vertical extent of
the jet stream is indicated (in flight levels) below the flight
level,e.g.FL270accompaniedby+
20 / -30 indicates that the height of the jet extends from FL
240 to FL 290.
Figures on arrows Speed in kt of movements of frontal systems

Flight levels inside small rectangle Height in flight levels of tropopause at spot locations e.g.
Low and high points
340 of the tropopause topography are
indicated by the letters L or H, respectively inside a pentagon
with the height in flight level.

11.4 RECEPTION OF WORLD AREA FORECAST CENTRE (WAFC) PRODUCTS

Wind and temperature charts for different flight level are given in GRIB (Gridded Data
in Binary) format and Significant Weather charts are in BUFR (Binary Universal Forecast
Representation) format.
These data and information is distributed either through Secured FTP or through satellite-
based broadcast system. The data disseminated by UK Met Office is through SADIS
(SAtellite DIstribution System) and it mainly covers Europe, Asia, Indian Ocean and
Africa. The data disseminated by U.S. NOAA broadcast system is through ISCS
(International Satellite Communications System) and mainly covers America and the
Pacific Ocean. Both these centres work in dual redundancy mode and in event of failure
of one centre, the other centre automatically takes over the responsibility.
Data formats on the secure SADIS FTP service:
OPMET, AIRMETs, GAMETs – Alphanumeric format
SIGWX Charts – PNG2format
BUFR3 encoded high level SIGWX information – BUFR; FM 94 BUFR (Binary
Universal Form for the Representation of meteorological data

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 GRIB1 (GRIB4 edition 1) encoded wind, temperature and humidity information
GRIB2 (GRIB edition 2) encoded wind, temperature and humidity information
GRIB2format
Volcanic ash advisory graphics and tropical cyclone advisory graphics – PNG format in
the PNG_FORMAT subfolders.
Volcanic ash and tropical cyclone advisory statements - Alphanumeric format
General login information for the service:
Host name sadisftp/metoffice.gov.uk
Domain name metoffice.gov.uk
IP Address 151.170.240.15
Access via web browser ftp://[username]:[password]@sadisftp.metoffice.gov.uk
11.5 GUIDANCE ON REPORTING SIGNIFICANT DISCREPANCIES IN WAFC
SIGWX CHARTS
Purpose of the report
To permit the meteorological offices to inform the WAFCs about significant
discrepancies on significant weather (SIGWX) forecasts issued by WAFCs.
To report significant discrepancies efficiently and unambiguously, and only when an
amendment to the SIGWX forecast is required.
Note: If a meteorological office finds a discrepancy, or a recurrent discrepancy, that does
not necessitate an amendment to the SIGWX according to Annex 3, it has the option to
inform the WAFC concerned by using route forecast (ROFOR) messages.
Usefulness of the report for the WAFCs
WAFC benefits from the notification by:
1. being informed of possible discrepancies;
2. analysing the proposal coming from a meteorological office;
3. re-initiating the forecasts model, if appropriate, taking into account the proposal; or
Sending an amendment for the SIGWX forecast concerned.
Steps to be followed by a meteorological office
WAFS SIGWX forecast is received by a meteorological office;
A meteorological office detects a significant discrepancy, in accordance with the criteria
for the amendment of SIGWX forecasts in Para 3.2.3 of ‘Manual on Meteorological
Services for Aviation in India’; no other differences shall be reported;
The meteorological office describes the significant discrepancy using the following rules:

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1. A notification of significant discrepancy concerning a forecast shall be
elaborated and sent between six and nine hours before the commencement of the
validity period of the forecast;
2. The notification is to be sent only to the WAFC concerned;
3. The notification is to be sent via e-mail or fax using the following e- mail
addresses or fax numbers:

Centre Fax Number E-Mail Address

WAFC Washington +1 816 880 0652 jhenderson@awc.kc.noaa.gov.
WAFC London +44 1344 854919 floorman@metoffice.com

4. The notification of significant discrepancies shall be prepared using the form in the
attachment
5. The notification is to be written in English.
Steps to be followed by a WAFC
The WAFC concerned acknowledges the receipt of the notification of the significant
discrepancy to the meteorological office that originated it, together with a brief comment
thereon and any action taken, using the same means of communication employed by the
meteorological office; and
If necessary, the WAFC issues an amendment for the SIGWX forecast concerned.
Attachment
Form to be used for the notification of a significant discrepancy on significant weather
forecast
Forecast Involved
Originating WAFC
ICAO Area
Flight Level
Validity Time
Validity Date

Description of the Discrepancy (IES)

(Error in expected position or intensity of phenomena; new expected phenomena.)

WAFC Forecast Proposal

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Phenomena FL Position Intensity FL Position Intensity Reference
Turbulence
Icing
Cumulonimbus
Sandstorms
Duststorms
Volcanic activity
Radioactive material
into the atmosphere

Note: The column “Reference” is to specify, for example, the observation, aircraft report
or the forecast model field that directed the meteorological office to inform of a significant
discrepancy. A copy of this information may be added to the form, if necessary.

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 Chapter - 12
ACTION FOR SEARCH & RESCUE OPERATION

SEARCH & RESCUE OPERATION (AIR TRAFFIC SERVICE AND SEARCH

& RESCUE UNIT)
Responsible authority
The Search & Rescue service in India is organized in accordance with the Standards
and Recommended Practices of ICAO Annex 12 by the Airports Authority of India in
collaboration with the Ministry of Defence, which has the responsibility for making
the necessary facilities available.
Area of responsibility
The Search & Rescue service is responsible for entire India territory including
territorial waters as well as airspace over high-seas encompassed by Chennai, Kolkata
and Mumbai FIRs and Delhi FIR.
Types of Service
1. Details of the Rescue Coordination Centres and related Rescue Units are given in
page GEN 3.6-2 to GEN 3.6-7. In addition, various other departments of the
Central and State Governments such as Railways, Post & Telegraph, All India
Radio, Police and District Collectors/Magistrates, Municipal and Local bodies,
Airline operators, Flying clubs, Professional pilots, Mercantile marine, Port Trust
and Armed Forces are available for search and rescue missions when required.
2. Satellite aided Search and Rescue
a. India has evolved a Satellite-aided Search and Rescue programme participation in
the COSPAS/SARSAT systems. It operates on 406MHz. Location accuracy is
normally within 5Km. The system will detect transmissions on this frequency
throughout the Indian Search and Rescue Region (SRR) and also SRR of
Bangladesh, Myanmar, Bhutan, Indonesia, Kenya, Malaysia, Maldives, Mauritius,
Nepal, Seychelles, Singapore, Somalia, Sri Lanka, Thailand and Tanzania.
b. Under this programme Local User Terminals (LUT) have been established at
Bangalore and Lucknow. Indian Mission Control Centre (INMCC) at Bangalore
is responsible for coordinating with Rescue Coordination Centres and other
International mission Control Centres.
c. INMCC at Bangalore is connected with RCCs at Chennai, Delhi, and Kolkata &
Mumbai through AFS network and any distress alert received for the areas covered
is automatically transmitted to the concerned RCC.
Rescue coordination centre (RCC)
There are four rescue coordination centres available in India as follows

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RCC-Chennai

Name Rescue Coordination Centre - Chennai

Postal Address Airports Authority of India, Chennai Airport,
Chennai 600027
Telephone 91-44-22560700(RCC), 91-44-22561803(FIC),
91-44-22560893 (WSO)
Fax 91-44-22560700(RCC), 91-44-22560894(WSO)
AFS VOMMYCYX
Telegraphic Aerodrome, Chennai
SAR Area Chennai FIR
Responsible agency Flight Information Centre, Chennai
or department
Name & location of Nil
Rescue Sub-Centre

RCC-Delhi

Name Rescue Coordination Centre - Delhi

Postal Address Airports Authority of India, I.G.I Airport, New Delhi
110017
Telephone 91-11-25654061(RCC), 91-11-25653457(FIC), 91-
11-25653283(WSO)
Fax 91-11-25654061(RCC), 91-11-25653284(WSO)
AFS VIDPYCYX
Telegraphic
SAR Area Delhi FIR
Responsible Flight Information Centre, Delhi
agency or
department
Name & location Nil
of Rescue Sub-
Centre

RCC-Kolkata

Name Rescue Coordination Centre - Kolkata

Postal Address Airports Authority of India, N.S.C.B. I. Airport,
Kolkata
Telephone 91-33-25130218(RCC), 91-33-25119520(WSO)
Fax 91-33-25130218(RCC), 91-33-25130134(WSO)
AFS VECCYCYX
Telegraphic

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 SAR Area Kolkata FIR
Responsible Flight Information Centre, Kolkata
agency or
department
Name & location Guwahati RSC
of Rescue Sub-
Centre

RCC-Mumbai

Name Rescue Coordination Centre - Mumbai

Postal Address Airports Authority of India, C.S.I. Airport, Mumbai
400099
Telephone 91-22-26819421(RCC),EPBAX 91-22-26828100
Extn 3421, 91-2226828002/8022(OCC/FIC), 91-
2226828088(WSO)
Fax 91-22-26828121(RCC), 91-2226819341(OCC/FIC),
91-2226828066(WSO)
AFS VABBYCYX
Telegraphic Air Com
SAR Area Mumbai FIR
Responsible Flight Information Centre, Mumbai
agency or
department
Name & location Nil
of Rescue Sub-
Centre

Agreement between RCC and MWO, IMD

Each FIR/ SAR area has a MWO for aviation weather watch in India and hence the
RCC has made an agreement with MWO level to take part in search and rescue
operation.
The General Manager (ATM) of the respective region is the responsible to maintain
and operate Rescue Coordination Centre (RCC) made an agreement with the
respective MWO Director (Met Office) who is responsible to maintain and operate
MWO to provide aviation weather services to contribute to safety improvement
regularity, of air navigation and efficiency.
Objective of the Agreement
The Meteorological Watch Office (MWO) aims to provide aviation weather services
to contribute to safety improvement regularity, of air navigation and efficiency. It
conducts aviation weather services according to the provisions of the International
Civil Aviation Organization (ICAO), Annex 3 and the World Meteorological
Organization (WMO), as well as standards and recommended practices of regional
agreements and convections in air navigation.

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The RCC (e.g. RCC Chennai) has the responsibility to organize and coordinate
Aeronautical Search and Rescue in the respective region (e.g. CHENNAI Search and
Rescue Region (SRR)). And the respective MWO (e.g. MWO Chennai) will arrange
for the supply of up to-date meteorological information to relevant ATS units and
search and rescue services units, as necessary, for the conduct of Search and Rescue
Operations.
Scope of this Agreement
Any meteorological information requested by RCC (e.g. RCC Chennai) unit in
connection with an aircraft emergency shall be supplied as rapidly as possible. The
Meteorological Watch Office (MWO) (e.g. MWO CHENNAI) in coordination with
the RCC (e.g. RCC CHENNAI,) shall arrange for the supply of up to-date
meteorological information to relevant ATS units and search and rescue services units,
as necessary, for the conduct of Search and Rescue Operations.
Extent of Assistance
The RCC and Meteorological Watch Office (MWO) agree to co-operate in the
following areas:
1. RCC (eg. RCC CHENNAI) will notify MWO (eg. MWO Chennai) ,the time,
location, extent of possibility area, ATS Units within the possibility area,
ATS Routes/Route segment within/passing through the possibility area and other
relevant details regarding the Aircraft requiring Search and Rescue Services in the
Form-A
2. MWO (eg. MWO CHENNAI) shall supply RCC (RCC CHENNAI) or as agreed
in coordination with RCC to relevant ATS units and search and rescue
services units, as, with the meteorological information they require in the Form-
B.
3. Respective MWO shall maintain liaison with the respective RCC throughout a
search and rescue operation.
4. MWO shall ensure that all pertinent meteorological observation and forecast data
are retained for at least 30 days.
Terms of Agreement
1. Keep information or other resources readily available which may be needed
for implementing this agreement.
2. RCC shall keep MWO fully and promptly informed of all SAR operations
which may involve use of Meteorological facilities.
3. RCC and MWO shall promptly respond to each other request for assistance.
Deviations
Temporary deviation from the procedures specified in this agreement shall only be
permitted in exceptional circumstances and not without prior co-ordination on a case-
by-case basis.
Annexure

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 Form –A
Serial Information Remarks
No.

1 The time of incident

2 Last Known Position
3 ATC unit of Last contact
4 Location or,
5 Possibility area
6 ATS Units within the possibility area
7 ATS Routes/ Segment within/ passing
through possibility area
8 Other relevant information
Call Sign
Type
Departure
Destination
Departure Time
Person on Board(POB)

Form B
Serial Information Remarks
No
1 Met reports including winds at different
levels in probability area/ on route
2 En-route Forecast for next 24 hrs from
the time (notified Form-A)
3 Supplementary information obtained
from aircraft
4 Meteorological information obtained
from aircraft
5 Meteorological information obtained
from ground weather radar
6 Special reports, SIGMET and AIRMET
information, warning etc
7 Any Other provision from doc 9377

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 Chapter - 13
ACTION FOR AIRCRAFT ACCIDENT INVESTIGATION

13.1 INTRODUCTION
Mishap may occur to an aircraft during any phase of its operation. Mishap to an
aircraft may be divided into two categories – Accidents and Incidents.
Damage may also be caused to parked or moored aircraft by weather phenomena.
13.2 Definitions
Accident: An occurrence associated with the operation of an aircraft which takes
place between the times any person boards the aircraft with the intention of flight
until such time as all such persons have disembarked, in which:
1. A person is fatally or seriously injured as a result of being in or upon the aircraft or
by direct contact with the aircraft or anything attached thereto; or
2. The aircraft incurs damage or structural failure which adversely affects the
structure, strength, performance or flight characteristics of the aircraft and which
would normally require major repair or replacement of the affected component; or
3. The aircraft is missing or is completely inaccessible.
Incident: An occurrence, other than an accident associated with the operation of an
aircraft which affects or could affect the safety of operation.
13.3 Accidents
13.3.1 Intimation to Headquarters’ Offices
Whenever an Aerodrome Meteorological Office (AMO) comes to know from any
source of an accident, the duty officer/officer-in-charge of the AMO should
immediately obtain the official time of occurrence of the accident from the local
aerodrome authorities. If it is an AMS, the message containing available information
should be send to the Director/ Meteorologist-in-charge of the controlling
Aerodrome Meteorological Office by name. All available details should be
immediately communicated through any available communication channel like
AMSS network, IMD VPN, Phone, or Telefax, by name to the Deputy Director
General of Meteorology (DDGM) of the parent Regional Meteorological Centre
(RMC). The DDGM (RMC) will in turn communicate the information using the
above modes of communication by name to Scientist F, Central Aviation
Meteorological Division (CAMD) and DDGM (RMC) of the region from which the
flight has originated. The first intimation shall contain the following:
1. Name of the Airline
2. Type and Call sign of the aircraft
3. Route followed or local flying
4. Details of Meteorological Briefing and documentation provided
5. Description of the accident/incident

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 6. Time of occurrence
7. Place of the accident/incident
8. Number of persons on-board
9. Casualty details, if any
10. Extent of damage to the aircraft
11. Reason of accident, if known
12. From whom the Message was received
13. Time of receipt of information
14. Whether entries have been made in the accident register and aviation log book
and signed by the officer in charge
15. Action taken on receipt of the information (Whether documents sealed and kept
under safe custody)
16. Whether Special Current weather observation was recorded as per para 3.2.5 of
IMD Aviation Manual or not.
17. Description of weather prevailed around the time of accident at the place/ site of
accident
18. Any other relevant details
In case of serious accidents involving loss of life or substantial damage to the
aircraft, the messages should commence with the identifier “AIRCRASH” and
should be sent without any delay. In addition, the information should be conveyed
to the DDGM (RMC) by telephone. The DDGM (RMC) in turn should convey the
information, by Telefax and telephone to Scientist F, CAMD/ DGM and DDGM
(RMC) of the region from which the flight had originated.
13.3.2 Responsibility of AMO & AMS
 Soon on getting information of an accident all relevant original documents
connected with the service rendered to the flight in question should be taken
possession of by the Officer-in-charge.
 Following are the list of documents to be kept in safe custody:
1. Office copy of documentation provided to the aircraft.
2. Office copies of relevant forecasts, aerodrome forecasts, and landing forecasts
3. Relevant SIGMET warnings
4. Routine, special and additional reports
5. Current Weather Diary
6. Radarscope Polar Diagrams/ Office copy of the DWR products, if used in
briefing
7. Office copies of satellite images, if used in documentation/ briefing.

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8. Briefing register/ relevant log page of OLBS
9. Log Books, if relevant
10. SIGMET information register
11. Office copies of relevant Aerodrome Warnings.
12. Office copies of WAFC WINTEMP charts, WAFC SIGWX charts, if used in
documentation.
13. Office copies of National SIGWX charts
14. All relevant information furnished to ATC, with proof, if possible, of receipt
by the recipient.
15. Autographic charts
16. Any other document that may be significant
 Where the meteorological briefing is being provided through web based briefing
system, the hard copies of the briefing materials should be taken possession of in
the same manner as in the case of manual briefing. Soft copies of the relevant
documents should also be preserved.
 No correction/alteration/modification shall be made in the original documents.
Immediately 5 copies of the original documents are to be readied.
 The documents in original together with two sets of copies should then be sealed
by the Officer-in-charge, in the presence of another officer/ member of staff and
kept under his safe custody.
 The officers sealing the documents should append their signatures together with
the time of sealing on the outer cover.
 In case the Officer-in-charge is not promptly available for sealing the documents
it shall be done by another officer/member of staff on duty.
 Three sets of copies duly attested by the Officer-in-charge should be forwarded
immediately under sealed cover to the Regional Meteorological Centre concerned
by Registered Post.
 Original sealed documents should be handed over to the Director of Air Safety/
Inspector of Accidents/ Investigator-in-charge or to an officer deputed by him for
the purpose, after obtaining a written request from him.
 The DDGM (RMC) should be kept informed of the action taken. The documents
sealed may be replaced in the Office records as soon as they are received back
from the Director of Air Safety/Inspector of Accidents/Investigator-in-charge or
from the officer deputed by him.
 In case no officials of DGCA call to collect the sealed documents, the documents
may be replaced in office records as soon as the final recommendations and report
of the investigating authority are received.
 In case no request is received for sealed documents, and no official
communication is received about the final recommendations and reports, the

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 officer-in-charge of the concerned AMO/ AMS could open the sealed covers and
the documents may be replaced in office records after the completion of one year
from the date of occurrence of accident/ incident.
 Proper entry in this regard may be made in the accident register under intimation
to DDGM (RMC).
 An ‘Aircraft Accident Register’ shall be maintained by all AMOs and AMSs and
entries shall be made regarding details of action taken in respect of each accident.
 List of original documents sealed for safe custody and subsequently handed over
to the Inspector of Accidents or other authorised representative of the Civil
Aviation Department, details of copies taken and furnished to the Regional
Meteorological Centre, details of current weather information supplied to Airline
Operators, current meteorological registers withdrawn from use etc., shall be
entered in the register.
 The ‘Aircraft Accident Register’ should be put up for perusal to DDGM (RMC)/
Scientist F, CAMD/ DGM/ IMD Safety Oversight Auditors during their
inspection visits to the office concerned.
 If during a particular quarter no aircraft accident occurs, a NIL entry may be made
for that quarter.
 Immediately after a meteorological office becomes aware of an aircraft accident
occurred at or in the vicinity of the local aerodrome, a special current weather
observation shall be recorded in case more than 5 minutes have elapsed since the
recording of the previous routine/ special/ additional report at the station.
 The duty officer/ officer-in-charge should initial this Special Current Weather
observation. However, in cases when the aircraft accident has occurred more than
half an hour earlier, no special observation need be taken.
13.3.3 Court Of Enquiry
 In order to avoid any controversy and embarrassment, all IMD officials should
desist from making any public statement expressing technical opinion or personal
views on meteorological factors/ services concerning the accident to the press or
other media or any agency or individual not authorised by government to
investigate the accident. It is not necessary or obligatory to obtain prior
permission of the DDGM (RMC) concerned either for attending a Court of
Enquiry or for producing meteorological documents to the Inspector of Accidents
or the Committee of Enquiry or the Court of Enquiry. A written request may be
obtained from the Inspector of Accidents or the Committee of Enquiry for
releasing the documents required by them. The officer-in-charge of the
meteorological office shall inform the DDGM (RMC) about attendance at Court
of Enquiry or the supply of meteorological documents.
 The DDGM (RMC) will in turn keep Scientist F, CAMD /DGM informed of such
attendance at Courts of Enquiry or supply of documents. DDGM, Regional
Meteorological Centres may nominate officers, preferably the Directors/
Meteorologists-in-charge of aviation forecasting offices or Meteorological
Centres to attend the investigation board as “observers” without prior approval of
Scientist F, CAMD or DGM.

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 The officer concerned should send a report to Scientist F, CAMD and DGM
through his DDGM (RMC) on his attendance at the investigation board.
 In giving evidence, only factual information about the weather at the time of
accident based on available recorded data, charts, and details of forecasts or
warning issued for the flight should be given. No attempt should be made to
express a view as to whether or not the accident has been caused by weather
conditions. Answers to all questions should be strictly factual, to the point and
precise. When specifically questioned by the Court of Enquiry, the Officer may
give information of a general nature on meteorological phenomena. It is desirable
that the officer tendering evidence before Courts of Enquiry goes prepared to
answer the probable questions (and supplementary) that might be asked and gives
precise answers.
 Under the existing provisions of the Indian Aircraft Act, the Inspector of
Accidents/ Court of Enquiry has the legal authority to question any member of
the meteorological staff on aspects, which may, or may not, be concerned with
the weather. There is no objection to the concerned persons answering questions
on aspects which may not be concerned with weather, but they should restrict
their answers to facts of which they have direct personal knowledge.
 Care should be taken not to offer opinions or remarks on the role of individual
officials, especially in fields in which the meteorological office has no concern.
 In the event of the meteorological staff expressing an opinion on non-
meteorological subjects, the responsibility of substantiating their statements
before a Committee of Enquiry (or other relevant investigating authority) rests
entirely on the persons concerned.
 Details of evidence given before Courts of Enquiry together with original
summons for giving evidence, should be sent to RMC concerned within a week
of tendering the evidence. RMC concerned should supply a copy of the same to
Scientist F, CAMD/ DGM along with their comments, if any.
 During the course of enquiry into aircraft accidents the Inspector of Accidents
may call for signed statements from concerned meteorological officials.
Whenever such requests are made, they should give the required signed
statements. The instructions contained in paragraphs 3.2.8 and 3.2.9 should be
strictly followed while giving such signed statements.
 The procedures are same in respect of investigation by IAF. Courts of Enquiry
also.
 Whenever any interested party other than Director General of Civil
Aviation(DGCA)/Court of Enquiry makes a request in writing for supply of
factual weather information covering the period of the accident, Meteorological
offices may supply the available observational data with the prior permission of
DDGM (RMC) concerned. Director/Met-in-charge of Meteorological Centres
may supply only factual information to parties and DDGM (RMC) concerned
should be kept informed. This authority should not be delegated by him to any
lower cadre. Scientist F,
 CAMD/ DGM should be informed by concerned DDGM (RMCs) of such

138
 requests received and replies issued.
13.3.4 Responsibilities of Regional Meteorological Centres
 Preliminary inquiry into all cases of aircraft accidents whether due to weather or
not, should be initiated by the DDGM concerned and the findings reported to
Scientist F, CAMD /DGM.
 In cases of accidents occurring in bad weather detailed investigation is necessary.
While forwarding the report of any aircraft accident to Scientist F, CAMD/ DGM,
the weather situation associated with the accident should be specifically
commented upon by the DDGM (RMCs).
 Detailed report may not be sent in case of accidents which are clearly not due to
weather conditions.
 However, this point may be brought out in the preliminary report and approval of
Scientist F, CAMD obtained for not submitting a detailed report. The same
procedure will apply for cases of incidents also.
 In the case of accidents, where more than one region is involved, the DDGM
(RMC) controlling the AMO or the AMS or the meteorological unit which
provided briefing and documentation or any other service for the flight in question
will send a report to Scientist F, CAMD/ DGM. The DDGM (RMC) in whose
region the accident occurred will also initiate a factual inquiry regarding the
weather conditions at the time and place of occurrence and supply of
meteorological data, if any, from meteorological offices in his region to the
Airport/ Air Traffic Control/ other Aviation Meteorological Offices and send his
report to Scientist F, CAMD / DGM.
 In the case of a major accident, the DDGM (RMC) may visit the site of accident
whenever necessary, for making an on-the-spot investigation. This authority
should not normally be delegated by him to any lower cadre.
13.3.5 Reports on Aircraft Accidents
The nature of all the correspondences pertaining to an aircraft accident/ incident
investigation shall be confidential and shall only be signed by DDGM (RMCs).
Detailed reports of investigation of accidents should be prepared by DDGM (RMCs)
and sent to Scientist F, CAMD /DGM as soon as possible after the occurrence of the
accident, preferably not later than a week after the accident.
Following are the contents of the Report:
I. General Description:
This part shall contain a general description of the accident with all relevant details such as:
(a) Name of the airline
(b) Type and call sign of the aircraft
(c) Route followed or local flying
(d) Details of Meteorological Briefing and documentation provided
(e) Description of accident/ incident
(f) Time of occurrence
(g) Place of accident/ incident
(h) No. of persons on board

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 (i) Casualty details, if any
(j) Extent of the damage to the aircraft
(k) Reason of accident, if known
(l) From whom the Message was received by the met office
(m) Time of receipt of information
(n) Whether entries have been made in the accident register and aviation log book
and signed by the officer-in-charge
(o) Action taken on receipt of the information (Whether documents sealed and
kept under safe custody)
(p) Whether Special Current weather observation was recorded or not
(q) Description of weather prevailed around the time of accident at the place/ site
of accident
(r) Any other relevant details
II. Brief on Meteorological services rendered:
A brief account of the meteorological services rendered to the aircraft in question with
copies of relevant documents as detailed below:
(a) Documentation provided
i) Reports
1. Routine, Special and Additional weather reports
ii) Forecasts
1. Route forecast (Chart form as well as Tabular form),
Terminal Aerodrome Forecast (TAF), SIGMET messages
and advisories, if any, utilized in the preparation of
documentation
2. Local/ Area forecast, aerodrome warnings for Parked and
Moored Aircraft and Take-off/ Landing Forecast
(TREND).
(b) Extracts from briefing registers, current weather registers, aviation log book,
telephonic discussions with ATC, operators etc.
(c) Autographic charts; where relevant
(d) Radar imageries/ Satellite imageries; where relevant
(e) Any other items having a bearing on the accident.
III. Description of the weather situation:
The weather situation at the time of the accident with a short description of the development
leading to it with copies of inferences, Bulletins etc., issued/received.
IV. Brief on media reports:
Reference to press reports together with relevant cuttings
V. Comments on adequacy of meteorological services provided:
Findings regarding adequacy or otherwise of meteorological services rendered; remarks on the
availability of basic data, state of completion of charts at the time of issue of forecasts, quality
of relevant analysis/prognosis, standards of forecasting etc. may be included as necessary
VI. Comments on procedural deficiencies
Remarks regarding adherence to current departmental instructions regarding writing of
forecasts, preparation of aerodrome reports etc.
VII. Local action taken on deficiencies noticed
VIII. Additional remarks, if any
All documents relating to the meteorological services provided to the ill-fated
aircraft are required to be checked

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 All the meteorological elements for which forecast was issued in TAF, TREND
Forecast, Local/Area Forecast, Route Forecast, Aerodrome Warning, etc., covering
the event are to be verified individually and a report along with comments are to be
sent to Scientist F, CAMD/ DGM.
DDGM (RMC) may also send his remarks on duration of current weather watch,
frequency and period of validity of all types of forecasts issued by the concerned
office and serviceability of aviation meteorological instruments in the airport to
CAMD/DGM.
Reports of investigations received from DDGM (RMCs) shall be examined in
CAMD. A consolidated report would be submitted by Scientist F, CAMD to DGM
giving his findings and recommendations.
13.4 Incidents
In cases of occurrence of incidents, the relevant documents need not be taken
possession of and sealed. The same procedures as in cases of aircraft accidents
should be followed for supply of any information or for tendering any evidence or
for giving signed statements required by the investigating officer of the Director
General of Civil Aviation (DGCA).
The procedure followed in cases of accidents by the aviation meteorological offices
in informing the Regional Meteorological Centre and by the latter to Scientist F,
CAMD/ DGM and the Regional Meteorological Centre from which the flight had
originated should also be followed in cases of incidents. However, the intimation
about the incident may be sent by post. The DDGM (RMCs) and Scientist F, CAMD
should investigate the cases of incidents in the same way as in cases of accidents.
For supply of information to any party other than the investigation officer of the
Civil Aviation Department, instructions given for accidents may be followed.
13.5 Damage to Parked and Moored Aircraft
Certain cases of damage to aircraft while parked and/or moored on ground are also
investigated by the Director General of Civil Aviation (DGCA) or by the airlines
themselves. When such investigations are done and information about weather
conditions are asked for by the investigating officer, a full report on the same as in
cases of accidents should be sent by the aviation meteorological office concerned to
the Regional Meteorological Centre. The DDGM (RMC) in turn shall send a report
to the Scientist F, CAMD/ DGM in the same manner as in cases of accidents.

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 Chapter - 14
PROCEDURE OF FORECAST VERIFICATION

14.1 TERMINAL AERODROME FORECAST (TAF)

Wind direction:
The forecast of wind direction is considered correct if the actual value is within ±20º
of the forecasted value.
Example:
If the forecast wind direction is 100º and the actual value is in between 80º and 120º,
then the forecast may be considered as correct.
Minimum percentage of cases within range is 80% of cases. That means, out of 100
forecasts for wind direction at least on 80 occasions, the forecast should be correct.
Wind speed:
The forecast of wind speed is considered correct if the actual value is within ±5kts of
the forecasted value.
Example:
If the forecast wind speed is 15kts and the actual value is in between 10 and 20kts,
then the forecast may be considered as correct
Minimum percentage of cases within range is 80% of cases. That means, out of 100
forecasts for wind speed at least on 80 occasions, the forecast should be correct.
Visibility:
The forecast of visibility is considered correct if the actual value is within ±200m up
to 800m.
Example:
If the forecast visibility is 600m and the actual value is in between 400m and 800m
then the forecast may be considered as correct.
The forecast of visibility is considered correct if the actual value is within ±30% of
the forecasted value in the visibility range of 800m to 10km.
Example:
If the forecast visibility is 1000m and if the actual value is in between 700m and
1300m, then the forecast may be considered as correct.
Minimum percentage of cases within range is 80% of cases. That means, out of 100
forecasts for visibility at least on 80 occasions, the forecast should be correct.
Precipitation:
The forecast of precipitation is considered correct when occurrence or non-occurrence
of precipitation is observed.

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 Example:
If a heavy precipitation is forecasted and heavy precipitation is observed then the
forecast may be considered as correct. Similarly, if moderate precipitation is
forecasted and moderate precipitation is observed then also the forecast can be
considered correct. Conversely, if precipitation is forecasted and no precipitation is
observed, then the forecast is to be taken as incorrect. Minimum percentage of cases
within range is 80% of cases. That means, out of 100 forecasts for precipitation at
least on 80 occasions, the forecast should be correct.
Cloud amount:
The forecast of cloud amount is considered correct when the actual value is within one
category when the cloud base height is below 450m.
Example:
When the cloud amount is forecasted to be SCT for cloud with base height below
450m, the forecast may be considered as correct, if the observed value is any of the
category among FEW, SCT or BKN.
The forecast of cloud amount is considered correct for clouds between 450m and
3000m if occurrence or non-occurrence of BKN or OVC is observed.
Example:
If the forecast of cloud amount is BKN for a cloud of base height 2000m and if BKN
cloud is observed the forecast can be considered as correct. On the contrary, if OVC
is forecasted and SCT is observed, then the forecast is to be taken as incorrect.
Minimum percentage of cases within range is 70% of cases. That means, out of 100
forecasts for cloud amount at least on 70 occasions, the forecast should be correct.
Cloud height:
The forecast of cloud height is considered correct when the actual value is within
±30m for cloud base heights up to 300m.
Example:
If the forecast of cloud height is 200m and if actual value is in between 170m and
230m then the forecast may be considered as correct.
The forecast of cloud height is considered correct if the actual value is ±30% of the
forecast value for cloud heights between 300m and 3000m.
Example:
If the forecasted cloud height is 1000m and if the observed value is in between 700m
and 1300m then the forecast may be considered as correct. Minimum percentage of
cases within range is 70% of cases. That means, out of 100 forecasts for cloud height
at least on 70 occasions, the forecast should come correct.
14.2 TREND FORECAST
Wind Direction:
The verification criterion and example is the same as that given in 13.1. However, the

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 minimum percentage of cases within range is 90% of cases.
Wind speed:
The verification criterion and example is the same as that given in 13.1. However, the
minimum percentage of cases within range is 90% of cases.
Visibility:
The verification criterion and example is the same as that given in 13.1. However, the
minimum percentage of cases within range is 90% of cases.
Precipitation:
The verification criterion and example is the same as that given in 13.1. However, the
minimum percentage of cases within range is 90% of cases.
Cloud amount:
The verification criterion and example is the same as that given in 13.1. However, the
minimum percentage of cases within range is 90% of cases.
Cloud height:
The verification criterion and example is the same as that given in 13.1. However, the
minimum percentage of cases within range is 90% of cases.
14.3 FORECAST FOR TAKE-OFF
Wind Direction:
The verification criterion and example is the same as that given in 13.1. However,
the minimum percentage of cases within range is 90% of cases.
Wind speed:
A forecast of wind speed is considered correct if the actual value is within ±5kts. The
forecast needs to be verified only for wind values up to 25kts.
Example:
If the forecast wind speed is 15kts and the actual value is in between 10kts and 20kts,
then the forecast may be considered as correct.
Minimum percentage of cases within range is 90% of cases.
Air Temperature:
An air temperature forecast is considered correct when the actual value is within ±1ºC
of the forecasted temperature.
Example:
If the forecast air temperature is 20ºC and actual value is in between 19ºC and 21ºC,
then the forecast may be considered as correct.
Minimum percentage of cases within range is 90% of cases.
Pressure value (QNH):
A forecasted pressure value is considered correct when the actual pressure value is

144
 within ±1hPa of the forecasted value.
Example:
If the forecasted pressure value is 1015hPa and actual value is in between 1014hPa
and 1016hPa then the forecast may be considered as correct.
Minimum percentage of cases within range is 90% of cases.
14.4 AREA/ LOCAL FORECAST
Upper air temperature:
A forecast of upper air temperature is considered correct if the actual value is within
±2ºC of the forecast value. Here the value is to be taken as the mean for 100NM area
around the aerodrome.
Example:
If the forecast of upper air temperature is 10ºC and actual value is in between 8ºC
and12ºC, then the forecast may be considered as correct.
Minimum percentage of cases within range is 90% of cases.
Upper wind:
A forecast of upper wind is considered correct if the actual value is within ±10kts of
the forecast value.
Example:
If the forecast of upper wind is 30kts and the actual value is in between 20kts and
40kts then the forecast may be considered as correct.
Minimum percentage of cases within range is 90% of cases.
Significant Weather Phenomena and Cloud:
Significant weather phenomena and cloud are considered correct with regards to the
occurrence or non- occurrence of weather phenomena within 100NM area.
Example:
If a significant weather phenomena was forecasted and if it occurs then the forecast
may be considered as correct. Conversely, if no significant weather was forecasted
and none observed, then also the forecast can be taken as correct. Similar is the case
with cloud also.
Minimum percentage of cases within range is 80% of cases.
The forecast of vertical extent of cloud is considered correct if the actual value is
within ±300m (1000ft) of the forecast value.
Example:
If the vertical extent of cloud was forecasted to be 4000m and if the actual value is
observed to be between 3700 and 4300m, and the forecast may be considered as
correct.
Minimum percentage of cases within range is 70% of cases.

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14.5 ROUTE/ FLIGHT FORECASTS
This verification method mainly follows ICAO norms, except for the upper wind,
which follows the old instruction. For the verification of the route forecast, the
following may kindly be borne in mind:
 When the wind direction is out by more than 90o the forecast is considered as
‘wrong’ except when both the forecast and actual wind speeds are less than 10kts.
 When the actual wind speed is more than 60kts, the above mentioned range for
speed shall be taken as 15 knots.
 The observation that fall within 50 kilometers on either side of the route may also
be considered for verifying a route forecast.
 Observations during the entire validity period are to be taken into account.
 If the route contains different sections, then verification is to be done for each
section.
14.6 SIGMET
There are no ICAO approved criteria for verification of SIGMET Warnings. However,
based on the ICAO criteria for Area forecast, this set of instructions has been
formulated. SIGMET for Tropical Cyclones and Volcanic Ash need not be verified as
they are issued following Advisories of the respective centers.
14.7 FORECAST VERIFICATION STATEMENT PROFORMA
Results of verification for the month of --------------------
Name of AMO/AMS ---------------------

146
 Name of forecast Elements % of cases within
range (% correct)
Wind direction
Wind speed
TAF Visibility
Precipitation
Cloud amount
Cloud height
Air temperature
Wind direction
Wind speed
TREND Forecast Visibility
Precipitation
Cloud amount
Cloud height
Wind direction
Forecast for take-off Wind speed
Air temperature
Pressure value(QNH)
Upper air temperature
Relative humidity
Area/Local forecasts Upper wind
Significant weather phenomena
Cloud
Upper-air temperature
Upper wind (Direction)
Route/Flight forecasts Upper wind (speed)
Significant en- Occurrence or
route weather non-occurrence
phenomena Location
Vertical extent
Flight level of
tropopause
Max wind level
Cloud Occurrence or
non-occurrence
Location
Vertical extent
Significant Occurrence or
weather non-occurrence
SIGMET phenomena Location
Vertical extent
Expected changes
in intensity

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14.8 OPERATIONALLY DESIRABLE ACCURACY OF FORECASTS
(Basis: Annex-3, 16th edition)

Element to be Operationally desirable accuracy of Minimum percentage of

Forecast Forecasts cases within range
TERMINAL AERODROME
FORECAST
Wind Direction ± 20° 80%of cases
Wind speed ± 10 km/h (5kt) 80% of cases
Visibility ± 200 m up to 800m 80% of cases
± 30% between 800 m and 10 km
Precipitation Occurrence or non-occurrence 80%of cases
Cloud amount One category below 450m (1500 ft) 70%of cases
Occurrence or non-occurrence of BKN
or OVC between 450 m
(1500 ft) and 3000 m
(10000 ft)
Cloud height ± 30 m (100 ft) up to 300m (1000 ft) 70% of cases
± 30% between 300m (1000 ft) and
3000m (10000 ft)
TREND FORCAST
Wind Direction ± 20° 90%of cases
Wind speed ±10 km/h (5kt) 90% of cases
Visibility ± 200 m up to 800m 90% of cases
± 30% between 800 m and 10 km
Precipitation Occurrence or non-occurrence 90%of cases
Cloud amount ±One category below 450m (1500 ft) 90%of cases
Occurrence or non-occurrence of BKN
or OVC between 450 m
(1500 ft) and 3000 m
(10000 ft)
Cloud height ± 30 m (100 ft) up to 300m (1000 ft) 90% of cases
± 30% between 300m (1000 ft) and
3000m (10000 ft)
TAKE-OFF FORECAST
Wind Direction ± 20° 90%of cases
Wind speed ±10 km/h (5kt) up to 50 km/h (25 kt) 90% of cases
Air ± 1°C 90%of cases
Temperature
Pressure value ± 1 hPa 90%of cases
(QNH)

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 AREA/ LOCAL FORECAST
Upper-air ± 2°C (Mean for 100 NM) 90%of cases
temperature
Upper wind ± 20 km/h (10 kt) 90%of cases
Significant Occurrence or non-occurrence within 80% of cases
weather 100NM area
phenomena Vertical extent: ± 300 m (1000 ft) 70%of cases
and cloud
ROUTE/ FLIGHT
FORECAST
Upper-air ± 2°C (Mean for 900 km (500 NM)) 90% of cases
temperature
Upper wind Direction: ± 30° 90% of cases

Speed: ± 10 kts 90% of cases

Significant en- Occurrence or non-occurrence 80% of cases

route weather Location: ± 100 km (60 NM) 70% of cases
phenomena
and cloud Vertical extent: ±300 m (1000 ft) 70% of cases
Flight level of tropopause: ±300 m 80% of cases
(1000 ft)
Max wind level: ±300 m (1000 ft) 70% of cases
SIGMET
Significant en- Occurrence or non-occurrence 80% of cases
route weather Location: ± 100 km (60 NM) 70% of cases
phenomena
Vertical extent: ±300 m (1000 ft) 70% of cases
Expected changes in intensity: 70% of cases
Occurrence or non-occurrence of the
same category (INTSF or WKN or NC)

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 Chapter - 15
QUALITY MANAGEMENT SYSTEM (QMS)

15.1 HIGHLIGHTS
In the Year 2001- QMS was introduced for Aeronautical Met Services.
In the year 2010- Amendments in QMS provisions were introduced.
15.2 ICAO DEFINITIONS
 Quality assurance: Part of quality management focused on providing confidence
that quality requirements will be fulfilled.
 Quality control: Part of quality management focused on fulfilling quality
requirements.
 Quality management: Coordinated activities to direct and control an organization
with regard to quality.
15.3 ICAO ANNEX 3 PROVISIONS
Para – 2.2
Each Contracting State shall ensure that the designated meteorological authority
establishes and implements a properly organized quality management system
comprising procedures, processes and resources necessary to provide for the quality
management of the meteorological information to be supplied to the users.
In regard to the exchange of meteorological information for operational purposes,
the quality system should include verification and validation procedures and
resources for monitoring adherence to the prescribed transmission schedules for
individual messages and/or bulletins required to be exchanged, and the times of their
filing for transmission
The quality system should be capable of detecting excessive transit times of
messages and bulletins received.
The quality system so established should be in conformity with the International
Organization for Standardization (ISO) 9000 series of quality assurance standards
and should be certified by an approved organization.
 Quality: Any feature or characteristic of a product or service that is needed to
satisfy user needs or achieve fitness for use.
 Quality for goods or products: Accessibility, Availability, Operability and
Durability
 Quality for services: Waiting time, Delivery time, Accuracy and Accessibility.
In context of aviation weather services and products, the word quality
communicates a high level of consistent performance, reliability and overall
credibility in meeting and satisfying the aviation industry’s identified needs.

150
 These characteristics are measurable and consequently can be used to monitor the
quality of the product or service
15.4 ADVANTAGES OF QMS
1. Enable the department to develop standard operating procedures (SOPs) for its
functions and activities. These SOPs are codified in a Quality Manual and
Procedures.
2. Compare and benchmark these (SOP) with other similar organizations in state or
international organizations.
3. Identify areas for improving functioning of the organization.
4. Codify institutional and personal memories and experiences for future generations.
Hence, when a person leaves, he or she will be able to leave behind SOPs for others
to follow and improve.
5. Bring in transparency and accountability in the operations.
6. Allow the organization to audit itself against the ISO standards.
7. The potential for losing the ISO certification during the audit every third year
allows the system to sustain itself over time
15.5 WHAT IS REQUIRED TO BE DONE?
1. Standardization and implementation of documented procedures for the
development of the end activities.
2. These specific standards are already in notified by WMO, ICAO and respective
governments.
3. Standards of generic nature is notified under ISO standards.
4. http://www.iso.org/iso/iso_catalogue
5. Structuring of the processes/services oriented to customer satisfaction and
continuous improvement.
6. Continuous monitoring of activities
15.6 PROCEDURE FOR QUALITY CONTROL AND CORRECTIVE ACTION
THEREON
1. The forecasts issued by AMOs shall be scrutinized by the AMOs-in-Charge on a
routine basis in order to find out the procedural lapses.
2. A random-check of TAF, Local/Area forecast, TREND forecast, route forecast
and Aerodrome warning of five consecutive days of a month shall be carried out
by the AMOs-in-Charge.
3. A register for noting the discrepancies and the remedial actions taken shall be
maintained.
4. A monthly statement of the same shall be submitted to DDGM (RMC) who will
forward it to CAMD with his comments.

151
 5. Verification of forecasts on systematic and routine basis as per the procedure laid
down to check, evaluate and improve the accuracy of forecasts issued. A monthly
statement of verification of Forecasts is sent to CAMD, NewDelhi.
6. Conducting of Refresher Training course periodically for improvement in
forecasts.
7. Preventive maintenance and servicing of Airport Met Instruments strictly
following maintenance and calibration schedule to aid and facilitate accurate
observations and reporting thereon of Aviation Meteorological Parameters.
15.7 SCOPE
1. To provide reliable meteorological information to the stakeholders and society
contributing positively in the decision – making process associated with any
related development.
2. To be a major contributor to the development of the knowledge and use of
meteorology and climatology at both National and International levels through
innovation.
3. Search for recognition, trust and high level of satisfaction of users through the
efficient monitoring of meteorological conditions, use of modern weather
forecasting tools and timely delivery of the products and services required.
4. Obtain National recognition through the ISO Certification
5. Search excellence through continuous improvement of activities, processes,
products, services and customer satisfaction.
6. Use and expand the knowledge of meteorology and in particular aviation
meteorology.
7. Involve staff in all processes, from data collection to realization of products;
8. Have an integrated view of the organization.
15.8 INSPECTION POLICY
A routine inspection of all airport Met Instruments are conducted by concerned
Regional Meteorological Centre along with Surface Observatory annually.
15.9 MAINTENANCE AND CALIBRATION SCHEDULE FOR AIRPORT
METEOROLOGICAL INSTRUMENT:
First Level Fortnightly Preventive Maintenance: Inspection of field site must be
carried out on fortnightly periodicity and Instrument inspection register is to be
maintained for recording deficiency, if any, and corrective action taken thereof. This
register should contain Fortnightly preventive maintenance and Quarterly controlled
corrective maintenance as well by dividing that register in to two parts by reversing
the register. Some of the check-list on commonly experienced deficiency / problems
(although not exhaustive and may vary from station to station and vary with type of
instruments) are given below for ready reference.
Check List:

152
1. Physical observation for rusting, damage on all equipment, fixtures, installation
bolts, screws & nuts.
2. General cleanliness at field site
3. Internal checking for all the cables connections, modules, units.
4. Checking connections of all sensor, if any loose connection
5. Checking of the commercial power supply provided at the field site including Earth-
Neutral voltage, condition of earthing
6. Checking of UPS supply and batteries provided at the field sites
7. Checking of cable modems / Radio modems and connections provided for data
communication
8. Checking of signal condition status at the site
9. Checking of Data Logger and their interfaces provided for data display
10. Checking of various display systems provided.
11. Cleaning of Enclosure at site.
12. Similar checking at MBR / ATC including signal cable connectivity, identification
of wires with proper marking / tag, cleanliness etc.
The following format may be maintained in the Instruments register:

Date Description of Reasons for Service Signature Signatur

& Preventive fault/ Details/ of the e of the
time Maintenance / Deficiency. Correctiv maintenanc Duty
Nature of e action e personnel officer /
Problem taken with Date in-
and time charge
with
Date and
time

IMD Duty official/In charge Remark

Second Level Controlled Corrective Quarterly Maintenance Schedule

Quarterly maintenance of all airport meteorological instruments must be carried out
in controlled corrective manner. Some of the check-list, though not exhaustive, are
given below for ready reference.

153
 Check List:
CWIS & DIWE:
1. Physical observation for rusting, damage on all equipment, fixtures, installation
bolts, screws & nuts.
2. Checking of the commercial power supply provided at the field site including
Earth-Neutral voltage, condition of earthing.
3. Checking of free movement of wind vane.
4. Checking wind-vane north setting with true NORTH.
5. Checking free movement of optical wind anemometer.
6. Cleaning of Ultrasonic wind sensor (if installed).
7. Checking and cleaning of Temperature/ Humidity sensor.
8. Checking and recording of pressure values (QFE/QNH).
9. Checking of data communication facilities (both wireless and with cable.
10. Checking of Data Logger and their interfaces provided for data display.
11. Cleaning of enclosure at site.
12. General cleanliness at site and in MBR/ATC.
13. The following format may be maintained in the Instruments register
The following format may be maintained in the Instruments register:

Date Description Reasons Service Signature of Signature

& of Preventive for fault/ Details / the of the Duty
time Maintenance/ Deficiency Corrective maintenance officer / in-
Nature of . action personnel charge with
Problem taken with Date and Date and
time time

IMD Duty official/In charge Remark

Calibration /Field Test Schedule:

Calibration/field testing of installed sensors with travelling standards should be done
as per schedule given below:
1. Wind Instrument: Once in six months
2. Temperature/Dew point/humidity: Once in 12 months
3. Pressure: Once in 12 months.

154
4. Transmissometer (RVR): Once in six months and prior to commencement of fog
season.
Procedure of Field Testing:
Field testing report/calibration should be done by concerned MC/RMC/MWO.
For Wind /temperature/Pressure sensors:
1. Installed sensors readings should be compared with travelling standards.
2. Minimum four (4) set observations at interval of three hours should be recorded
(may be in parallel with synoptic observations).
3. Duly signed Calibration/Field test report should be sent in the format enclosed
below and a copy maintained for office record at station for showing inspecting
authorities including DGCA.
Field Test Report on Calibration and Inter Comparison with Travelling
Standard Kit:
1. Name of instrument/sensor:
2. Serial Number:
3. Make and Model:
4. Field test observations:
Date and time Actual Value Value in Difference
travelling
standard kit
Mean difference
Accuracy required as per ICAO

Operationally Desirable Accuracy of Measurement:

Reference:
ICAO Annexure 3, 19th edition, July 2016, ATTACHMENT A. OPERATIONALLY
DESIRABLE ACCURACY OF MEASUREMENT OR OBSERVATION.

155
APPENDICES
 Appendix - I
NOTATIONS USED IN FLIGHT DOCUMENTATION

Severe squall line symbol:

In flight documentation for flights operating up to FL100. This symbol refers to
“squall line”.

1
Radioactive materials in the atmosphere symbol:
The following information shall be included at the side of the chart:
1. Radioactive material symbol;
2. Latitude/Longitude of the accident site;
3. Date and time of accident;
4. Check NOTAM for further information.
Volcanic eruption symbol:
The following information shall be included at the side of the chart:
1. Volcanic eruption symbol;
2. Name an international number of volcano (if known);
3. Latitude/Longitude;
4. Date and time of the first eruption (if known);
5. Check SIGMETs and NOTAM or ASHTAM for volcanic ash.
Freezing precipitation:
This symbol does not refer to icing due to precipitation coming into contact with an
aircraft, which is at a very low temperature.
Visible ash cloud symbol:
Visible ash cloud symbol applies only to model VAG not to SIGWX charts.
Note: Height indications between which phenomena are expected, top above base as
per chart legend.
Abbreviations used to describe clouds:
Type
CI=Cirrus AS =Altostratus ST = Stratus
CC = Cirrocumulus NS = Nimbostratus CU = Cumulus
CS=Cirrostratus SC = Stratocumulus
CB= Cumulonimbus
AC =Altocumulus
Amount
Clouds except CB
SKC = Sky clear (0/8) FEW = Few (1/8 to2/8)
SCT = Scattered (3/8 to 4/8) OVC = Overcast (8/8)
CB only
ISOL = individual CBs (isolated)

2
OCNL = well-separated CBs (occasional)
FRQ = CBs with little or no separation (frequent)
EMBD= CBs embedded in layers of clouds or concealed by haze (embedded)
Height
Heights are indicating on SWH and SWM charts in flight levels (FL), top over base.
When XXX is used, tops or bases are outside the layer of the atmosphere to which
the chart applies.
In SWL charts:
1. Heights are indicated as altitudes above mean sea level;
2. The abbreviation SFC is used to indicate ground level.
Depicting of lines and systems on specific charts
Models SWH and SWM – Significant weather charts (high and medium)

Scalloped line Demarcation of areas of significant weather

Heavy broken line Delineation of area of CAT
Heavy solid line Position of jet stream axis with indication of wind
Interrupted by wind direction position of jet stream axis with indication of
arrow and flight level wind direction, speed in kts and height in flight level.
The vertical extent of the jet stream is indicated (in flight
levels) below the flight level, e.g. FL 270 accompanied
by + 20/-30 indicates that the height of the jet extends
from FL 240 to FL 290.
Figures on arrows Speed in kts of movements of frontal systems
Flight levels inside Height in flight levels of tropopause at spot locations
small rectangle e.g. 340
Low and high points of the
tropopause topography are indicated
by the letters L or H, respectively inside a Pentagon
with the height in flight level.

3
 Appendix - II
AVIATION TERMINOLOGY

DEFINITIONS
When the following terms are used in the practices for Meteorological Service for
national and international Air Navigation, they have the following meanings:
Aerodrome: A defined area on land or water (including any buildings, installations
and equipment) intended to be used either wholly or in part for the arrival, departure
and surface movement of aircraft.
Aerodrome climatological summary: Concise summary of specified meteorological
elements at an aerodrome, based on statistical data.
Aerodrome climatological table: Table providing statistical data on the observed
occurrence of one or more meteorological elements at an aerodrome.
Aerodrome control tower: A unit established to provide air traffic control service to
aerodrome traffic.
Aerodrome elevation: The elevation of the highest point of the landing area.
Aerodrome meteorological office: An office, located at an aerodrome, designated to
provide meteorological service for air navigation.
Aerodrome reference point: The designated geographical location of an aerodrome.
Aeronautical fixed service (AFS): A telecommunication service between specified
fixed points provided primarily for the safety of air navigation and for the regular,
efficient and economical operation of air services.
Aeronautical fixed telecommunication network (AFTN): A worldwide system of
aeronautical fixed circuits provided, as part of the aeronautical fixed service, for the
exchange of messages and/or digital data between aeronautical fixed stations having
the same or compatible communications characteristics.
Aeronautical meteorological station: A station designated to make observations and
meteorological reports for use in air navigation.
Aeronautical mobile service: A mobile service between aeronautical stations and
aircraft stations, or between aircraft stations, in which survival craft stations may
participate; emergency position-indicating radio beacon stations may also participate
in this service on designated distress and emergency frequencies.
Aeronautical telecommunication station: A station in the aeronautical
telecommunication service.
Aircraft: Any machine that can derive support in the atmosphere from the reactions
of the air other than the reactions of the air against the earth’s surface.
Aircraft observation: The evaluation of one or more meteorological elements made
from an aircraft in flight.
AIRMET information: Information issued by a meteorological watch office

4
concerning the occurrence or expected occurrence of specified en-route weather
phenomena, which may affect the safety of low-level aircraft operations and which
was not already included in the forecast issued for low-level flights in the flight
information region concerned or sub-area thereof. (Not issued in India at present)
Air-report: A report from an aircraft in flight prepared in conformity with
requirements for position, and operational and/or meteorological reporting.
Air traffic services unit: A generic term meaning variously, air traffic control unit,
flight information centre or air traffic services reporting office.
Alternate aerodrome: An aerodrome to which an aircraft may proceed when it
becomes either impossible or inadvisable to proceed to or to land at the aerodrome of
intended landing. Alternate aerodromes include the following:
Take-off alternate: An alternate aerodrome at which an aircraft can land shall this
become necessary shortly after take-off and it is not possible to use the aerodrome
of departure.
En-route alternate: An aerodrome at which an aircraft would be able to land after
experiencing an abnormal or emergency condition while en route.
Destination alternate: An alternate aerodrome to which an aircraft may proceed
shall it become impossible or inadvisable to land at the aerodrome of intended
landing.
Note: The aerodrome from which a flight departs may also be an en-route or a
destination alternate aerodrome for that flight.
Altitude: The vertical distance of a level, a point or an object considered as a point,
measured from mean sea level (MSL).
Approach and landing operations using instrument approach procedures:
Instrument approach and landing operations are classified as follows:
Non-precision approach and landing operations. An instrument approach and
landing, which utilises lateral guidance but does not utilise vertical guidance.
Approach and landing operations with vertical guidance. An instrument approach
and landing which utilises lateral and vertical guidance but does not need the
requirements established for precision approach and landing operations.
Precision approach and landing operations. An instrument approach and landing
using precision lateral and vertical guidance with minima as determined by the
category of operation.
Note: Lateral and vertical guidance refers to the guidance provided either by; a
ground-based navigation aid; or computer generated navigation data.
Categories of precision approach and landing operations:
Category I (CAT I) operation: A precision instrument approach and landing with
a decision height not lower than 60 m (200 ft) and with either a visibility not less
than 800 m or a runway visual range not less than 550 m.
Category II (CAT II) operation: A precision instrument approach and landing

5
 with a decision height lower than 60 m (200 ft), but not lower than 30 m (100 ft),
and a runway visual range not less than 300 m.
Category III A (CAT III A) operation: A precision instrument approach and
landing with:
1. A decision height lower than 30 m (100 ft) or no decision height; and
2. A runway visual range not less than 175 m.
Category III B (CAT III B) operation: A precision instrument approach and
landing with:
1. A decision height lower than 15 m (50 ft) or no decision height; and
2. A runway visual range less than 175 m but not less than 50 m.
Category III C (CAT III C) operation: A precision instrument approach and
landing with no decision height and no runway visual range limitations.
Note: Where decision height (DH) and runway visual range (RVR) fall into
different categories of operation, the instrument approach and landing operation
would be conducted in accordance with the requirements of the most demanding
category (e.g. an operation with a DH in the range of CAT III A but with an RVR
in the range of CAT III B would be considered a CAT III B operation or an
operation with a DH in the range of CAT II but with an RVR in the range of CAT
I would be considered a CAT II operation).
Approach control unit: A unit established to provide air traffic control service to
controlled flights arriving at, or departing from, one or more aerodromes.
Appropriate ATS authority: The relevant authority designated by the State
responsible for providing air traffic services in the airspace concerned.
Area control centre: A unit established to provide air traffic control service to
controlled flights in control areas under its jurisdiction.
ASHTAM: A special series of NOTAM notifying by means of a specific format,
change in activity of a volcano, a volcanic eruption and/or volcanic ash cloud that is
of significance to aircraft operations.
Automatic dependent surveillance (ADS): A surveillance technique in which
aircraft automatically provide, via a data link, data derived from on-board navigation
and position-fixing systems, including aircraft identification, four dimensional
position and additional data as appropriate.
Aviation meteorological office: A general term used for the meteorological offices
designated to provide meteorological service for air navigation.
Briefing: Oral commentary on existing and/or expected meteorological conditions.
Cloud of operational significance: A cloud with the height of cloud base below 1500
m (5000 ft) or below the highest minimum sector altitude, whichever is greater, or a
cumulonimbus cloud or a towering cumulus cloud at any height.
CAMD: Central Aviation Meteorological Division
Consultation: Discussion with a meteorologist or another qualified person of existing

6
and/or expected meteorological conditions relating to flight operations; a discussion
includes answers to questions.
Control area: A controlled airspace extending upwards from a specified limit above
the earth.
Cruising level: A level maintained during a significant portion of a flight.
Elevation: The vertical distance of a point or a level, on or affixed to the surface of
the earth, measured from mean sea level.
Extended range operation: Any flight by an aeroplane with two turbine power- units
where the flight time at the one power-unit inoperative cruise speed (in ISA and still
air conditions), from a point on the route to an adequate alternate aerodrome, is greater
than the threshold time approved by the State of the Operator.
Flight crew member: A licensed crew member charged with duties essential to the
operation of an aircraft during a flight duty period.
Flight documentation: Written or printed documents, including charts or forms,
containing meteorological information for a flight.
Flight information centre: A unit established to provide flight information service
and alerting service.
Flight information region: An airspace of defined dimensions within which flight
information service and alerting service are provided.
Flight level: A surface of constant atmospheric pressure, which is related to a specific
pressure datum 1013.2 HectoPascal (hPa), and is separated from other such surfaces
by specific pressure intervals.
Note.1: A pressure type altimeter calibrated in accordance with the Standard
Atmosphere:
1. When set to a QNH altimeter setting, will indicate altitude;
2. When set to a QFE altimeter setting, will indicate height above the QFE
reference datum; and
3. When set to a pressure of 1013.2 hPa, may be used to indicate flight levels.
Note.2: The terms “height” and “altitude”, used in Note 1, indicate altimetric rather
than geometric heights and altitudes.
Forecast: A statement of expected meteorological conditions for a specified time or
period, and for a specified area or portion of airspace.
GAMET area forecast: An area forecast in abbreviated plain language for low- level
flights for a flight information region or sub-area thereof, prepared by the
meteorological office designated by the meteorological authority concerned and
exchanged with meteorological offices in adjacent flight information regions, as
agreed between the meteorological authorities concerned. (Not issued in India at
present).
Grid point data in digital form: Computer processed meteorological data for a set
of regularly spaced points on a chart, for transmission from a meteorological computer

7
to another computer in a code form suitable for automated use.
Note: In most cases such data are transmitted on medium or high-speed
telecommunications channels.
Height: The vertical distance of a level, a point or an object considered as a point,
measured from a specified datum.
Heliport: An aerodrome or a defined area on a structure intended to be used wholly
or in part for the arrival, departure and surface movement of helicopters.
Human Factors principles: Principles which apply to aeronautical design,
certification, training, operations and maintenance and which seek safe interface
between the human and other system components by proper consideration to human
performance.
International Airways Volcano Watch (IAVW): International arrangements for
monitoring and providing warnings to aircraft of volcanic ash in the atmosphere.
Note: The IAVW is based on the cooperation of aviation and non-aviation operational
units using information derived from observing sources and networks that are
provided by States. The watch is coordinated by ICAO with the cooperation of other
concerned international organisations.
Level: A generic term relating to vertical position of an aircraft in flight and meaning
variously height, altitude or flight level.
Meteorological authority: The authority providing or arranging for the provision of
meteorological service for international air navigation on behalf of a Contracting
State.
Meteorological Bulletin: A text comprising meteorological information preceded by
an appropriate heading.
Meteorological information: Meteorological report, analysis, forecast, and any other
statement relating to existing or expected meteorological conditions.
Meteorological report: A statement of observed meteorological conditions related to
a specified time and location.
Meteorological satellite: An artificial Earth satellite making meteorological
observations and transmitting these observations to Earth.
Minimum sector altitude: The lowest altitude which may be used which will provide
a minimum clearance of 300 m (1000 ft) above all objects located in the area contained
within a sector of a circle of 46 km (25 NM) radius centered on a radio aid to
navigation.
NOTAM: A notice distributed by means of telecommunication containing
information concerning the establishment, condition or change in any aeronautical
facility, service, procedure or hazard, the timely knowledge of which is essential to
personnel concerned with flight operations.
Observation (meteorological): The evaluation of one or more meteorological
elements.
Operational control: The exercise of authority over the initiation, continuation,

8
diversion or termination of a flight in the interest of the safety of the aircraft and the
regularity and efficiency of the flight.
Operational flight plan: The operator’s plan for the safe conduct of the flight based
on considerations of aeroplane performance, other operating limitations and relevant
expected conditions on the route to be followed and at the aerodromes concerned.
Operational planning: The planning of flight operations by an operator.
Operator: A person, Organisation or enterprise engaged in or offering to engage in
an aircraft operation.
Performance-based navigation (PBN): Area navigation based on performance
requirements for aircraft operating along an ATS route, on an instrument approach
procedure or in a designated airspace.
Pilot-in-command: The pilot designated by the operator, or in the case of general
aviation, the owner, as being in command and charged with the safe conduct of flight.
Prevailing visibility: The greatest visibility value, observed in accordance with the
definition of “visibility”, which is reached or exceeded within at least half the horizon
circle or within at least half of the surface of the aerodrome. These areas could
comprise continuous or non-continuous sectors.
Note: This value may be assessed by human observation and/or instrumented systems.
When instruments are installed, they are used to obtain the best estimate of the
prevailing visibility.
Prognostic chart: A forecast of a specified meteorological element(s) for a specified
time or period and a specified surface or portion of airspace, depicted graphically on
a chart.
Quality assurance: Part of quality management focused on providing confidence that
quality requirements will be fulfilled (ISO 9000).
Quality control: Part of quality management focused on fulfilling quality
requirements (ISO 9000).
Quality management: Coordinated activities to direct and control an Organisation
with regard to quality (ISO 9000).
Regional air navigation agreement: Agreement approved by the Council of ICAO
normally on the advice of a regional air navigation meeting.
Reporting point. A specified geographical location in relation to which position of
an aircraft can be reported.
Rescue coordination centre: A unit responsible for promoting efficient organisation
of search and rescue services and for coordinating the conduct of search and rescue
operations within a search and rescue region.
Runway: A defined rectangular area on a land aerodrome prepared for the landing
and take-off of aircraft.
Runway visual range (RVR): The range over which the pilot of an aircraft on the
centre line of a runway can see the runway surface markings or the lights delineating
the runway or identifying its centre line.

9
Search and rescue services unit: A generic term meaning, as the case may be, rescue
coordination centre, rescue sub centre or alerting post.
SIGMET information: Information issued by a meteorological watch office
concerning the occurrence or expected occurrence of specified en-route weather
phenomena, which may affect the safety of aircraft operations.
Standard isobaric surface: An isobaric surface used on a worldwide basis for
representing and analyzing the conditions in the atmosphere.
Threshold: The beginning of that portion of the runway usable for landing.
Displaced Threshold: A threshold not located at the extremity of a runway.
Touchdown zone: The portion of a runway, beyond the threshold, where it is intended
landing aeroplanes first contact the runway.
Tropical cyclone: Generic term for a non-frontal synoptic-scale cyclone originating
over tropical or sub-tropical waters with organised convection and definite cyclonic
surface wind circulation.
Tropical Cyclone Advisory Centre (TCAC): A meteorological centre designated by
regional air navigation agreement to provide advisory information to meteorological
watch offices, world area forecast centres and international OPMET data banks
regarding the position, forecast direction and speed of movement, central pressure and
maximum surface wind of tropical cyclones.
Upper-air chart: A meteorological chart relating to a specified upper-air surface or
layer of the atmosphere.
Visibility: Visibility for aeronautical purposes is the measure of:
1. The greatest distance at which a black object of suitable dimensions, situated near
the ground, can be seen and recognised when observed against a bright
background;
2. The greatest distance at which lights in the vicinity of 1000 candelas can be seen
and identified against an unlit background.
Note: The two distances have different values in air of a given extinction coefficient,
and the latter varies with the background illumination. The former is represented by
the meteorological optical range (MOR).
Volcanic Ash Advisory Centre (VAAC): A meteorological centre designated by
regional air navigation agreement to provide advisory information to meteorological
watch offices, area control centres, flight information centres, world area forecast
centres and international OPMET data banks regarding the lateral and vertical extent
and forecast movement of volcanic ash in the atmosphere following volcanic
eruptions.
VOLMET: Meteorological information for aircraft in flight.
Data link - VOLMET (D-VOLMET): Provision of current aerodrome routine
meteorological reports (METAR) and aerodrome special
meteorological reports (SPECI), aerodrome forecasts (TAF), SIGMET, special air-
reports not covered by a SIGMET and, where available, AIRMET via data link.

10
 VOLMET broadcast: Provision, as appropriate, of current METAR, SPECI, TAF
and SIGMET by means of continuous and repetitive voice broadcasts.
World Area Forecast Centre (WAFC): A meteorological centre designated to
prepare and issue significant weather forecasts and upper-air forecasts in digital form
on a global basis direct to States by appropriate means as part of the aeronautical fixed
service.
World area forecast system (WAFS): A worldwide system by which world area
forecast centres provide aeronautical meteorological en-route forecasts in uniform
standardised formats.
TERMS USED WITH A LIMITED MEANING
The following terms are used with a limited meaning as indicated below:
1. To avoid confusion in respect of the term “Service” between the meteorological
service considered as an administrative entity and the service which is provided,
“Meteorological Authority” is used for the former and “Service” for the latter;
2. “Provide” is used solely in connection with the provision of service;
3. “Issue” is used solely in connection with the cases where the obligation specifically
extends to sending out the information to a user;
4. “Make available” is used solely in connection with cases where the obligation ends
with making the information accessible to a user; and
5. “Supply” is used solely in connection with cases where either 3 or 4 applies.

11
 Appendix - III
LIST OF REGISTERS TO BE MAINTAINED BY DIFFERENT TYPES OF
AVIATION MET OFFICES

Serial Registers/ log books MWO AMO AMS

No.
1 Accident register ✔ ✔ ✔
2 Registers for noting lapses, ✔ ✔
deficiencies, procedural
mistakes etc.
3 Current Weather Register ✔ ✔ ✔
4 Briefing Register ✔ ✔ ✔
5 De-briefing Register ✔ ✔
6 Aviation Action Diary ✔ ✔
(Routine)
7 Aviation Action Diary ✔ ✔
(Non- Routine)
8 In-flight and Post-flight ✔ ✔
report register
9 Aviation Log book ✔ ✔ ✔
10 FIR Warning/ SIGMET ✔ ✔
Register
11 Aerodrome Warning ✔ ✔
Register
12 Register for coded ✔ ✔
ROFORs, TAFs etc.
13 Verification of Aviation ✔ ✔
Forecasts
14 Register regarding ✔ ✔ ✔
Implementation of
instructions and circulars
15 NOTAM Register ✔ ✔ ✔
16 Radar Scope Observation ✔ ✔
Register
17 METAR Plotting Register ✔ ✔ At AMS where
(Format not provided) TREND Forecast
is issued

12
 FORMAT OF REGISTERS

India Meteorological Department

FIR Warning/ SIGMET Register
…………………… Airport
From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Serial Date and Phenomenon Text of the Name, Remarks

Number time of for which warning Designation
issue SIGMET is and signature
issued of the issuing
officer

Note:
(1) Entry regarding ‘NIL SIGMET is also to be made in the register.
(2) This register may be maintained by AMOs and AMSs to keep account of the
SIGMETs received by them.

India Meteorological Department

Aerodrome Warning/ Warning for Light Aircraft/ Wind Shear Warning Register
………………………Airport

From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Date Serial Phenomenon Text of the Name, The Any other

and Number for which warning Designation forecasts remarks
time of Warning is and signature amended
issue issued of the issuing
officer

13
 India Meteorological Department
Register for ROFOR/ 9hr TAF/ 30hr TAF
…………………… Airport

From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Date and Type of Text of the message Name, Remarks

time of message Designation
issue and signature
of the issuing
officer

Note:
(1) In view of the availability of typed messages, it is not necessary to maintain the old
TAFOR/ ARFOR register (MET T-9/ OBS 466).
(2) It is also not necessary to enter the text of all routine TAFs and ROFORs only when
special TAF/ ROFOR/ ARFOR are issued text of the message is to be entered.
(3) In column “Type of message”, entry may be made as ‘ROFOR’, ‘9 hr TAF’, or ‘30
hr TAF’
India Meteorological Department
Aviation Log Book
………………………Airport
From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Date and Time Details of To whom Mode of Remarks and

information supplied communication signature of the
supplied Duty Officer

Note:
Particulars of all information supplied to any party on special request may be entered in
this register.

14
 India Meteorological Department
Register for noting lapses, deficiencies and procedural mistakes
………………………Airport
From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Serial Date, Time Discrepancy Reference para Designation Remarks and

No. and Type of noticed of manual, and signature sign of the
message code book, and of the officer concerned officer
other guidance notifying the in regard to the
material discrepancy compliance of
the correct
procedure

Note:
AMOs may call for the sample messages from AMSs for scrutiny and maintain record
of that.
India Meteorological Department
Register for Verification of Aviation Forecasts
………………………Airport
From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Type of Date and Actual Forecast Realized Accuracy Remarks

forecast period of charts Significant Significant
validity based on Weather Weather
which the
forecast
was
issued

Note:
(1) The random verification of forecasts may be done preferably on days when weather
occurred.
(2) The quarterly statement of verification of forecasts should be an extract of this
register.

15
 India Meteorological Department
NOTAM Register
………………………Airport
From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Serial No. Date and Subject Text of the Copies given Remarks
Time of issue message to

India Meteorological Department

Aviation Action (Diary-I) Routine
………………………Airport
From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Sl. No Date Name of Validity Issued Addresses Mode of Remarks/

and forecast/ for dissemination Signature of
Time of warning/ station/ D.O
issue bulletin region
“A” Duty

“B” Duty

“C” Duty

Note:
(1) In this register entries may be made of all the routine like, TAFs, ROFORs, Area
Forecasts, Local forecasts etc., for own aerodrome as well for the associated aerodromes.
The addresses to which the messages are routinely sent may be given in the first page of
the register. They need not be repeated daily.
(2) If the schedule of work remains the same, entries need not be made daily. Whenever
there is a change in the schedule, it is to be entered in the register and signature of the
Duty officer may be obtained at the end of the month.

16
 India Meteorological Department
In-flight/ Post flight Register
………………………Airport
From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Date Sl. No. Name of No. of in-flight reports No. of post flight reports
Airlines Expected Received Expected Received
1 2 3 4 5 6

India Meteorological Department

Instructions / Circulars Implementation Register
………………………Airport

From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Circulars/ Date of If not Remarks

instructions with Implementation/ implemented,
DDGM (WF) UOI action reason for the same
No. and date completed

1 2 3 4

17
 India Meteorological Department
Aviation Action (Diary-II) Non-Routine

………………………Airport

From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Date: Day of week: Shift:

Sr. Time of Particulars of items of work Parties to whom information is to Actual Remarks and
No. receipt of be supplied time of signature of
intimation Message Station Route Period Station Airline Mode Priority issue Duty Officer

Note: Entries in this register may be restricted to documentation supplied to non-scheduled flights.

18
 India Meteorological Department
Radarscope Observation Register

………………………Airport

From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Date Time of Range Characte Description Intensity Tendency Stage Duration/ Altitude Signature Signature Remarks
observation of ristics ( AZ1 / R1 of Echo of Echo of Speed of Radar of Duty
UTC Radar AZ2 / R2 ) Echo Asst. officer if
scope (N no Echoes
miles)

19
 India Meteorological Department
Current Weather Register
………………………Airport
From (Year/Month/ Date) To (Year/Month/ Date) Page No.
Date: ……………….
Wind Visibility Weather Individual Cloud Layer Temperature
Hours
GMT

Dry Wet Dew

Direction Mean Extreme Horizontal Runway Significant Ns/CC Ns/CC Ns/CC Ns/CC bulb Bulb Point
wind wind visibility Visual Weather (0.1°C) (0.1°C) (0.1°C)
speed speed Range in
(Knots) (Knots) Meters hshshs hshshs hshshs hshshs
Number of
runway to
which it
refers
GGgg ddd ff fmfm VVVV VRVRVRVRD W`W` T`T` Td`Td`
fnfn RDR

1 2 3 4 5 6 7 8 9 10 11 12 13 14

20
 Pressure 0.1mb (.001) Additional information For stations reporting 2 minutes Observer’s
(not to be coded in METAR / SPECI Mean Wind Initials
reports)

Attached QFE QFF QNH Total Present Past Supplementary Direction Mean Maximu
thermomet amount Weather Weather Information Speed m Speed
er °A/°C of all (Knots) (Knots) /
Bar as clouds Minimum
Read Speed
(Knots)

PH PH N WW W ddd ff fmfm / fnfn

PH PH

15 16 17 18 19 20 21 22 23 24 25 26

21
 India Meteorological Department
Briefing Register
………………………Airport
From (Year/Month/ Date) To (Year/Month/ Date) Page No.
Date: ………………..
Serial Date Route E.T.D. Name of Call sign of Time of Briefing Name and Signature of the Signature of Duty
No. Airline the Briefing Notes Designation of the person receiving Officer (with
Aircraft person receiving briefing and remarks if any)
briefing and documentation
documentation

Note: At stations where On Line Briefing System is functioning, details of the logins by the users may be maintained.
India Meteorological Department
Briefing Register
………………………Airport
From (Year/Month/ Date) To (Year/Month/ Date) Page No.
Date: ………………..
Serial Date and time Route and Name of Flight level Debriefing Remarks, if any (Indicate Signature of Debriefing
No. of Debriefing period of airline and notes whether flight cross section Officer
Flight call sign of handed in)
Aircraft

22
 India Meteorological Department
Aircraft Accident/ Incident Investigation Register
………………………Airport

From (Year/Month/ Date) To (Year/Month/ Date) Page No.

Serial No. Date, Time Name of Call sign Route Followed Details of First C.W. Observation recorded as
Place, airline/ of Accident information required
region of Flying club aircraft report received
accident from
at time
1 2 3 4 5 6 7 8

Details of MET services List of documents Details of copies taken/ Details of action taken Signature of Met
rendered withdrawn/sealed and particulars of /findings of R.M.C I/C Officer I/C
parties to whom communicated to Remarks
supplied DDGM(WF)/DGM
9 10 11 12 13 14

23
 MONTHLY AVIATION STATISTICS FORMAT
मासिक वैमासिक िाांख्यिकी का प्रारूप
Format for Monthly Aviation Statistics
माह/ Month: __________________
क्र.िां. S/No. पूवाािुमाि /ां चेतावसिय ां के प्रकार पूवाािुमाि /ां चेतावसिय ां की
Type of forecasts/ warnings िांिा Number of forecasts
/ warnings

वि .मौ .का .का नाम /

Name of AMO / AMS
1 वनर्ाा रित उड़ान पूिाा नुमान
Scheduled flight F/C
मेट .टी/ 3टी 4MET T3 / T4
चाटा प्रारूप Chart form
ऑन-लाइन ब्रीव िं ग
On-line Briefing
2 अवनर्ाा रित उड़ान पूिाा नुमान
Non-scheduled flight F/C
मौखिक Oral
मेट .टी / 3टी 4MET. T3 / T4
चाटा प्रारूप Chart form
3 मागा पूिाा नुमान Route forecast
4 विमानक्षेत्र पूिाा नुमान
Terminal Aerodrome forecast
5 प्रिृवत(टर ें ड )पूिाा नुमान
Trend forecast

6 विमानक्षेत्र चेतािनी
Aerodrome Warning
7 स्थानीय पूिाा नुमान Local forecast
8 क्षेत्रीय पूिाा नुमान Area forecast
9 विग्मेट – चेतािनी
SIGMET- Warnings
10 उत्प्रस्थान पूिाा नुमान
Take-off Forecast
11 कुलयोग TOTAL
12 डी – ब्रीव िं ग De-Briefing

Forwarded to: Officer-in-charge

24
 SCHEDULED OF OBSERVATONAL HOURS IN DIFFERENT AVIATION OFFICES

Hours of
Name of station Type of met reports and
Serial Type and frequency operation/
/ Location supplementary
No. of observations Type of
indicator information included
station
Agartala/ VEAT Hourly + Half hourly METAR/SPECI/TREND H24
1
From 2300-0730
Agatti /VOAT Hourly + Half hourly METAR/SPECI HO/A
2
during HO
Ahmedabad/ Half hourly METAR/SPECI/TREND H24
3
VAAH
Aizwal Half hourly during HO METAR/SPECI HO/B
4 (Lengpui)/
VEAZ
5 Amritsar/VIAR Hourly + Half hourly METAR/SPECI H24/C
Aurangabad/ Hourly + Half hourly METAR/SPECI H24
6 VAAU From 0030-0530 hrs
Bangalore Half hourly METAR/SPECI/TREND H24
7 (Devanahalli)/ From 2330-1300 hrs
VOBL HO
Bangalore(HAL) Hourly + Half hourly METAR/SPECI/TREND H24/C
8 /VOBG From 0000-1800 hrs
Belgaum Hourly + Half hourly METAR/SPECI H24/A
9
/VOBM during HO
Bhavnagar/ Hourly + Half hourly
10 METAR/SPECI HJ
VABN From 0630-0800 hrs
Bhopal Hourly + Half hourly METAR/SPECI H24
11 (Bairagarh)/ during HO
VABP
Bhubaneshwar Hourly + Half hourly METAR/SPECI/TREND H24
12
/VEBS HO
Coimbatore/ Half hourly during HO METAR/SPECI H24/C
13
VOCB
Calicut Half hourly during HO METAR/SPECI/TREND H24/C
14 (Kozhikode)/
VOCL
Chennai / Half hourly METAR/SPECI/TREND H24
15
VOMM
Cooch- Behar/ Hourly + Half hourly METAR/SPECI HJ/B
16
VECO
Dehradun A/R METAR/SPECI HJ/A
17
/VIDN
18 Delhi /VIDP Half hourly METAR/SPECI/TREND H24
Delhi (SFD)/ Hourly + Half hourly METAR/SPECI HJ/B
19
VIDD

25
 Dimapur/ Hourly + Half hourly METAR/SPECI HJ/B
20
VEMR
21 Diu / VADU METAR/SPECI HJ/C
Fursatganj A/R METAR/SPECI HJ/B
22 (Raibarelly)/
VIRB
Gaggal Hourly + Half hourly METAR/SPECI
23 (Dharamsala)/ during 1030-1600 hrs
VIGG
24 Gaya/ VEGY Half hourly in HJ METAR/SPECI HJ/B
Guwahati/ Hourly + Half hourly METAR/SPECI/TREND H24
25
VEGT
Hubli/ VOHB Hourly + half hourly METAR/SPECI HO
26
during HO
Hyderabad Hourly + half hourly METAR/SPECI/TREND H24
27 (Shamshabad)/ during HO
VOHS
Hyderabad/ Hourly + Half hourly METAR/SPECI/TREND H24/C
28
VOHY during HO
Imphal/ VEIM Hourly + Half hourly METAR/SPECI HJ/C
29
during HO
Indore/ VAID Hourly + Hsalf hourly METAR/SPECI H24
30
during HO
31 Jabalpur/ VAJB Hourly METAR/SPECI HS
Jaipur/ VIJP Hourly + Half hourly METAR/SPECI H24
32
during HO
Jamshedpur/ Hourly + Half hourly METAR/SPECI HJ/B
33
VEJS during HO
34 Kandla/ VAKE A/R METAR/SPECI HJ
35 Kochi/ VOCI Half hourly METAR/SPECI/TREND H24/C
Khajuraho/ Hourly METAR/SPECI HJ
36
VAKJ
37 Kolkata/ VECC Half hourly METAR/SPECI/TREND H24
38 Kota/ VIKO Hourly METAR/SPECI HJ/B
Kulu (Bhuntar)/ Hourly + Half hourly METAR/SPECI HJ/A
39
VIBR
North Hourly + Half hourly METAR/SPECI HJ/C
40 Lakhimpur/ during HO
VELR
41 Ludhiana/ VILD A/R METAR/SPECI HJ/A
Lucknow/ VILK Hourly + Half hourly METAR/SPECI/TREND H24
42
during HO
Madurai/ Hourly + Half hourly METAR/SPECI HO/C
43
VOMD during HO
Mangalore Hourly + Half hourly METAR/SPECI HJ/C
44
(Bajpe)/ VOML during HO
45 Mohanbari/ Half hourly METAR/SPECITREND H24

26
 VEMN
Mumbai Half hourly METAR/SPECI/TREND H24
46 (Santacruz)/
VABB
Mumbai (Juhu)/ Hourly + Half hourly METAR/SPECI HJ
47
VAJJ during HO
Mysore/ VOMY Hourly + Half hourly METAR/SPECI HO
48
during HO
Nanded/ VAND Hourly + Half hourly METAR
49
during HO
Nagpur/ VANP Hourly + Half hourly METAR/SPECI/TREND H24
50 to meet operational
requirements
51 Pantnagar/ VIPT A/R METAR/SPECI HJ/A
52 Pasighat/ VEPG Hourly + Half hourly METAR/SPECI HJ/B
Patna/ VEPT Hourly + Half hourly METAR/SPECI/TREND H24
53
during HO
Pondicherry Hourly + Half hourly METAR/SPECI HO/A
54
/VOPC during HO
Porbandar/ Hourly + Half hourly METAR/SPECI HJ
55
VAPR during HO
Puttaparthi/
56
VOPN
Raipur/ VARP Hourly + Half hourly METAR/SPECI 0300-1230
57
during HO
Rajahmundry/ Hourly + Half hourly METAR/SPECI HO/A
58
VORY during HO
Rajkot/ VARK Hourly + Half hourly METAR/SPECI H24
59
during HO
Ranchi/ VERC Hourly + Half hourly METAR/SPECI HJ/B
60
during HO
Salem/ VOSM Hourly + Half hourly METAR/SPECI HO
61
during HO
Shimla /VISM Hourly + Half hourly METAR/ SPECI
62 during 0800-1500 hrs
Shillong Hourly + Half hourly METAR/SPECI HJ/B
63 (Barapani)/ during HO
VEBI
64 Surat/ VASU A/R METAR/SPECI HJ
Tiruchirapalli/ Hourly + Half hourly METAR/SPECI H24/A
65
VOTR during HO
Tirupati/ VOTP Hourly + Half hourly METAR/SPECI HO/B
66
during HO
Thiruvananthapu Hourly + Half hourly METAR/SPECI/TREND H24
67
ram/VOTV during HO
Tuticorin / A/R METAR/SPECI HJ/A
68
VOTK

27
 Udaipur/ VAUD Hourly + Half hourly METAR/SPECI HJ/B
69
during HO
Vadodara Hourly + Half hourly METAR/SPECI HJ
70 (Baroda)/ during HO
VABO
Varanasi/ Hourly + Half hourly METAR/SPECI H24
71
VABN during HO
Vijaywada Hourly + Half hourly METAR/SPECI HJ/A
72 (Gannavaram)/ during HO
VOBZ
Notes:
Hourly observations are recorded at: Ahmedabad, Mumbai, Hyderabad, Chennai, Nagpur,
Tiruchirapalli and Thirivananthapuram at HH + 40 min. and HH + 10 min.
Kolkata and Patna at HH + 50 min. and HH + 20 min.
Delhi, Lucknow, Amritsar, Varanasi and Jaipur at HH + 30 min and HH + 00
At all other stations:HH + 00 min. HH = Full Hour UTC
Half-hourly observations are recorded half-an-hour after the hourly observations, mentioned
in Note 1 above.
SPECI’s and ADDITIONAL REPORTS are prepared whenever warranted, throughout the
hours of watch.
Abbreviation and Legends:

H24: Continuous day & night service

HO: Service available to meet operational requirement.
HJ: Observations from Sunrise to Sunset.
HS: Service available during hours of scheduled operations
A/R: As and when required.
A: AMS upto 7 hrs watch
B: AMS upto 14 hrs watch
C: AMS round the clock watch.

28
 Appendix - IV
TEMPLATE FOR THE LOCAL ROUTINE (MET REPORT) AND LOCAL SPECIAL
(SPECIAL) REPORTS
Key:
M = Inclusion mandatory, part of every message;
C = Inclusion conditional, dependent on meteorological conditions;
O = Inclusion optional.
Element Detailed content Template(s) Examples
Identification of Type of report MET REPORT or SPECIAL MET REPORT SPECIAL
the type of report
(M)
Location indicator ICAO location indicator Nnnn VABB
(M) (M)
Time of the Day and actual time of the nnnnnnZ 221630Z
observation (M) observation in UTC
Surface wind (M) Name of the element (M) WIND WIND 240/8KT

Runway(O)2 RWY nn[L] or RWY nn[C] or RWY nn[R] WIND RWY 18 TDZ 190/11KT

WIND VRB2KT WIND

Runway section (O)3 TDZ CALM

Wind direction (M) nnn/ VRB BTN nnn/ AND nnn/ or VRB WIND VRB BTN 350/AND
C 050/2KT
Wind speed (M) [ABV] n[n]KT A
L WIND 270/ABV 99KT
M
Significant speed MAX [ABV] nn [n] MNM n [n] WIND 020/10KT VRB BTN 350/AND
variations(C)4 070/
Significant directional VRB BTN nnn/ --
WIND RWY 14R MID 140/11KT
variations(C) 5 AND nnn/
Runway Section(O)3 MID

Wind Direction(O)3 nnn/ VRB BTN nnn/ AND nnn/

or
VRB C
Wind speed(O)3 [ABV] n[n]KT A
L
M
Significant speed MAX [ABV]nn[n] MNM n [n]
variations(C)4
Significant directional VRB BTN -
variations(C)5 nnn/AND nnn/
Runway Section(O)3 END
WIND RWY 27 TDZ 240/16KT
Wind Direction(O)3 nnn/ VRB BTN nnn/ AND nnn/ MAX27 MNM10 END 250/14KT
or C
VRB A
Wind speed(O)3 [ABV] n[n]KT L
M
Significant speed MAX [ABV]nn[n] MNM n [n]
variations(C)
Significant directional VRB BTN -
variations (C) nnn/AND nnn
Visibility(M) Name of the element (M) VIS

Runway (O)2 RWY nn[L] or RWY nn[C] or RWY nn[R] C VIS 350M CAVOK
A VIS 7KM
V VIS 10KM
Runway section (O)3 TDZ O
K
Visibility (M) nn[n][n]M or n[n]KM VIS RWY 09 TDZ 800M END 1200M

29
 Runway section (O)3 MID

Visibility (O)3 nn[n][n]M or n[n]KM

Runway section (O)3 END VIS RWY 18C TDZ 6KM RWY 27
Visibility (O)3 nn[n][n]M or n[n]KM TDZ 4000M
RVR (C) Name of the element (M) RVR RVR RWY 32 400M RVR
RWY 20 1600M
Runway (C) RWY nn[L] or RWY nn[C] or RWY nn[R]
Runway section (C) TDZ
RVR (M) [ABV or BLW] nn[n][n]M RVR RWY 10L BLW 50M RVR
RWY 14 ABV 2000M RVR RWY
10 BLW 150M RVR RWY 12
ABV 1200M

RVR RWY 12 TDZ 1100M MID ABV

Runway section (C) MID
1400M
RVR (C) [ABV or BLW] nn[n][n]M
Runway section (C) END RVR RWY 16 TDZ 600M MID 500M
RVR (C) [ABV or BLW] nn[n][n]M END 400M
RVR RWY 26 500M RWY 20
800M
Present weather Intensity of present weather FBL or -
(C) (C) MOD or
HVY
Characteristics and type of DZ or RA or IC or FG or MOD RA HZ
present weather (C) SN or SG or BR or SA or HVY TSRA FG
PL or DS or DU or HZ or HVY DZ VA
SS or FU or VA or FBL SN MIFG
FZDZ or SQ or PO or
FZRA or FC or TS or HVY TSRASN
SHGR or BCFG or FBL SNRA
SHGS or BLDU or
SHRA or BLSA or FBL DZ FG
SHSN or BLSN or HVY SHSN BLSN
TSGR or DRDU or
TSGS or DRSA or
TSRA or DRSN or
TSSN FZFG or
MIFG or
PRFG
Cloud (M) Name of the element (M) CLD
Runway (O)2 RWY nn[L] or RWY nn[C] or RWY nn[R] CLD NSC
CLD SCT 300M OVC 600M (CLD
Cloud amount (M) or FEW or OBSC NSC SCT 1000FT OVC 2000FT)
vertical visibility (O) SCT or
BKN or CLD OBSC VER VIS 150M
OVC (CLD OBSC VER VIS 500FT)

Cloud type (C) CB or TCU - CLD BKN TCU 270M

(CLD BKN TCU 900FT)

Height of cloud base or the nn[n][n]M(or [VER VIS CLD RWY 08R BKN 60M RWY 26
value of vertical nnn[n]FT) nn[n]M(or VER VIS BKN 90M
visibility(C) nnn[n]FT)] (CLD RWY 08R BKN 200FT
RWY 26 BKN 300FT)

30
 Air temperature Name of the element (M) T T17
(M) Air temperature (M) [MS]nn TMS08
Dew –point Name of the element (M) DP DP15
temperature (M) Dew-point temperature (M) [MS]nn DPMS18
Pressure values Name of the element (M) QNH QNH 0995HPA
(M) QNH (M) nnnnHPA QNH 1009HPA
Name of the element (O) QFE QNH 1022HPA QFE 1001HPA
QFE (O) [RWY nn[L] or RWY nn[C] or RWY nn[R]]nnnnHPA QNH 0987HPA QFE RWY 18
[RWY nn[L] or RWY nn[C] or RWY nn[R] nnnnHPA] 0956HPA
RWY 24 0955HPA
Supplementary Significant meteorological CB or TS or MOD TURB or SEV TURB or WS or GR or FC IN APCH
information (C) phenomena(C) SEV SQL or MOD ICE or SEV ICE or FZDZ or FZRA or WS IN APCH 60M-WIND:
SEV MTW or SS or DS or BLSN or FC13 360/25KT
Location of the IN APCH[nnnM-WIND nnn/nnKT] or WS RWY 12
phenomenon(C) IN CLIMBOUT[nnnM-WIND nnn/nnKT] or RWY
nn[n]
Recent weather(C) REFZDZ or REFZRA or REDZ or RE[SH]RA or RERASN or
RE[SH]SN or RESG or RESHGR or RESHGS or REBLSN or
RESS or REDS or RETSRA or RETSSN or RETSGR or REFZRA
RETSGS or REFC or REPL or REVA or CB IN CLIMB-OUT RETSRA
RETS
Trend Forecast (O) Name of the element (M) TREND TREND NOSIG
Change indicator (M) NOSIG BECMG or TEMPO TREND BECMG FEW 600M
Period of change (C) FMnnnn and/or TLnnnn TREND TEMPO 250/35KT MAX 50
Or ATnnnn TREND BECMG AT1800 VIS 10KM
Wind (C) nnn/ [ABV] n[n]KT [MAX[ABV]nn] NSW
TREND BECMG TL1700 VIS 800M
Visibility (C) VIS nn[n][n]M
FG
or C
TREND BECMG FM1030 TL1130
VIS n[n]KM A
CAVOK
FBL or - NSW V
TREND TEMPO TL1200 VIS 600M
Weather phenomenon: MOD or O
BECMG AT1230 VIS 8KM NSW
intensity (C) HVY K
CLD NSC
Weather phenomenon: DZ or RA or IC or FG or TREND TEMPO FM0300 TL0430
characteristics and type(C) SN or SG or BR or SA or MOD FZRA
PL or DS or DU or HZ or TREND BECMG FM1900 VIS 500M
SS or FZDZ FU or VA or HVY SNRA
or FZRA or SQ or PO or TREND BECMG FM1100 MOD SN
SHGR or FC or TS or TEMPO FM1130 BLSN
SHGS or BCFG or
SHRA or BLDU or
SHSN or BLSA or
TSGR or BLSN or
TSGS or DRDU or
TSRA or DRSA or
TSSN DRSN or
FZFG or
MIFG or
PRFG
Name of the element (C) CLD
Cloud amount and vertical FEW or SCT OBSC NSC TREND BECMG AT1130 CLD OVC
visibility (C) or BKN or 300M
OVC
Cloud type (C) CB or TCU - TREND TEMPO TL1530 HVY
Height of cloud base or the [VER VIS SHRA CLD BKN CB360M
value of vertical visibility (C) nn[n][n]M nn[n]M]

Notes:
1. Fictitious location.
2. Optional values for one or more runways.
3. Optional values for one or more sections of the runway.

31
 TEMPLATE FOR METAR AND SPECI
Key:
M = inclusion mandatory, part of every message; C = inclusion conditional, dependent on
meteorological conditions or method of observation; O = inclusion optional.
Element Detailed content Template(s) Examples
Identification of Type of report (M) METAR or SPECI METAR
the type of SPECI
report (M)
Location ICAO location indicator Nnnn VABB
indicator (M) (M)
Time of the Day and actual time of the nnnnnnZ 221630Z
observation (M) observation in UTC (M)
Surface wind Wind direction (M) Nnn VRB 24008KT VRB02KT
(M)
Wind speed (M) [P]nn[n] 19011KT
00000KT
140P99KT

Significant speed G[P]nn[n]

variations (C) 12006G18KT
Units of measurement(M) KT 24016G27KT

Significant directional nnnVnnn -

variations(C) 02010KT 350V070
Visibility (M) Minimum visibility (M) nnnn 0350 CAVOK
C 7000
Direction of the minimum N or NE or E or SE or S or SW or W or A 9999
visibility(C) NW V
Maximum visibility(C) nnnn O 0800E
K
Direction of the maximum N or NE or E or SE or S or SW or W or 1100SE 7000NW
visibility(C) NW 1200S 6000W
RVR (C) Name of the element (M) R R32/0400
Runway (M) nn[L]/or nn[C]/or nn[R]/ R12R/1700
R10/M0050
RVR (M) [P or M]nnnn R14L/P2000

R16L/0650 R16C/0500
R16R/0450 R17L/0450
RVR past tendency(C) U,D or N
R12/1100U R26/05500N
R20/0800D
Present weather Intensity or proximity of -or+ --- VC
(C) present weather (C)
Characteristics and type of DZ or RA or IC or FG or FG or RA HZ VCFG
present weather (M) SN or SG or BR or SA or PO or +TSRA FG VCSH
PL or DS or DU or HZ or FC or +DZ VA VCTS
SS or FZDZ FU or VA or DS or -SN MIFG VCBLSA
or FZRA or SQ or PO or SS or
SHGR or FC or TS or TS or +TSRASN
SHGS or BCFG or SH or -SNRA
SHRA or BLDU or BLSN
SHSN or BLSA or or
TSGR or BLSN or BLSA DZ FG
TSGS or DRDU or or +SHSN BLSN
TSRA or DRSA or BLDU
TSSN DRSN or or VA
FZFG or
MIFG or
PRFG
Cloud (M) Cloud amount and height FEWnnn or VVnnn or NSC FEW015 VV005
of cloud base or vertical SCTnnn or VV/// OVC030 VV/// NSC
visibility (M) BKNnnn or
OVCnnn SCT010 OVC020

32
 BKN009TCU
SCT008 BKN025CB
Cloud type (C) CB or TCU -

Air and dew- Air and dew-point [M]nn/[M]nn 17/10

point temperatures (M) 02/M08
temperature M01/M10
(M)
Pressure values Name of the element (M) Q Q0995
(M) Q1009
QNH (M) Nnnn Q1022
Q0987
Supplementary Recent weather (C) REFZDZ or REFZRA or REDZ or RE[SH]RA or REFZRA
information (C) RERASN or RE[SH]SN or RESG or RESHGR or RETSRA
RESHGS or REBLSN or RESS or REDS or
RETSRA or RETSSN or RETSGR or RETSGS or
RETS or REFC or REVA or REPL
Wind shear (C) WS Rnn[l] or WS Rnn[C] or WS Rnn[R] or WS WS R03
ALL RWY WS ALL RWY
WS R18C
Trend forecast Change indicator (M) NOSIG BECMG or TEMPO NOSIG BECMG FEW020
(O)
Period of change (C) FMnnnn and/or
TLnnnn
or
ATnnnn
Wind (C) nnn[P]nn[G[P]nn]KT TEMPO 25036G50KT

Visibility (C) nnnn C

A BECMG FM1030 TL1130 CAVOK
V
O BECMG TL1700 0800 FG
K
BECMG AT1800 9000 NSW

BECMG FM1900 0500 +SNRA

Weather phenomenon: - or + - N
Intensity (C) S
BECMG FM1100 SN TEMPO FM1130 BLSN
Weather phenomenon: DZ or RA or IC or FG W
characteristics and type(C) SN or SG or or BR or TEMPO FM0330 TL0430 FZRA
PL or DS or SA or DU
SS or FZDZ or HZ or
or FZRA or FU or VA
1 or SQ or
FC PO or FC
SHGR or or TS or
SHGS or BCFG or
SHRA or BLDU or
SHSN or BLSA or
TSGR or
BLSN or
TSGS or
DRDU or
TSRA or
TSSN DRSA or
DRSN or
FZFG or
MIFG or
PRFG

Cloud amount and height FEWnnn or VVnnn or N TEMPO TL 1200 0600 BECMG
of cloud base or vertical SCTnnn VV/// S AT1200 8000 NSW NSC
visibility (C) or C
BKNnnn BECMG AT1130 OVC010
or
OVCnnn
Cloud type (C) CB or TCU -
TEMPO TL1530 +SHRA BKN012CB

33
 TEMPLATE FOR TERMINAL AERODROME FORECAST (TAF)
Key:
M = Inclusion mandatory, part of every message
C = Inclusion conditional, dependent on meteorological conditions or method of
observation
O = Inclusion optional

Elements Detailed content Template Examples

Identification of the typeType of forecast TAF or TAF AMD TAF
of forecast (M) (M) TAF AMD
Location indicator (M) ICAO location Nnnn VABB
indicator (M)
Time of issue of forecast Day and Time of nnnnnnZ 160000Z
(M) issue of the forecast
in UTC (M)
Days and period of Days and period of the nnnn/nnnn 1606/1615
validity of forecast validity of the 0812/0918
(M) forecast in UTC (M)
Surface wind (M) Wind Direction (M) nnn or VRB 24008KT VRB02KT
Wind speed (M) (P)nn(n) 19011KT
(P indicates that the forecast wind speed is more 00000KT
than 99 knots. There is no aeronautical requirement 140P99KT
to report surface winds of 100 knots or more; 12006G18KT
however, provision has been made by giving “(n)” 24016G27KT
for reporting wind speeds up to 199 knots for non-
aeronautical purposes,
as necessary)
Significant speed G(P)nn(n)
variations (C) “G” Indicates the forecast maximum wind speed
(gust)
Units of KT
measurement (M)
Visibility (M) Minimum visibility Nnnn 0350 CAVOK
(M) 7000
9000
9999
Weather (C) Intensity of weather - or +
phenomena (C)
Characteristics and DZ or RA or IC or FG or RA HZ
type of weather SN or SG or BR or SA or +TSRA FG
phenomena (C) PL or DS or DU or HZ or C -FZDZ PRFG
SS or FU or VA or A
FZDZ or SQ or PO or V +TSRASN SNRAFG
FZRA or FC or TS or O
SHGR or BCFG or K
SHGS or BLDU or
SHRA or BLSA or
SHSN or BLSN or
TSGR or DRDU or
TSGS or DRSA or
TSRA or DRSN or
TSSN FZFG or
MIFG or
PRFG

34
Cloud (M) Cloud amount and FEWnnn VVnnn NSC FEW010 VV005 OVC020
height of base or or or VV///
vertical visibility (M) SCTnnn or BKNnnn VV///
or SCT005 BKN012
OVCnnn
Cloud type (C) CB or TCU -- SCT008 BKN025CB NSC

Expected significant Change or probability PROB30 (TEMPO) or PROB40 (TEMPO) or

changes to one or more indicator (M) BECMG or TEMPO or FM
of the above elements
during the period of Period of occurrence nnnn/nnnn
validity (C) or change (M)

Wind (C) nnn(P)nn(G(P)nn)KT or

VRBnnKT TEMPO 0815/0818 25035G50KT
((P indicates that the forecast wind speed is more
than 99 knots) TEMPO 2212/2214 17012G25KT
“G” Indicates the forecast maximum wind 1000 TSRA
speed (gust) SCT010CB BKN 020

Minimum visibility Nnnn

(C) BECMG 3010/3011 00000KT
Weather phenomena: - or + NSW 2400 OVC010
intensity (C)
PROB30 1412/1414 0800 FG
Weather phenomena: DZ or RA or IC or FG or
characteristics and SN or SG or BR or SA or BECMG 1412/1414 RA TEMPO
type (C) PL or DS or DU or HZ or 2503/2504 FZRA TEMPO
SS or FU or VA or 0612/0615 BLSN
FZDZ or SQ or PO or PROB40 TEMPO 2923/3001
FZRA or FC or TS or C 0500 FG
SHGR or BCFG or A
SHGS or BLDU or V
SHRA or BLSA or O
SHSN or BLSN or K
TSGR or DRDU or
TSGS or DRSA or
TSRA or DRSN or
TSSN FZFG or
MIFG or
PRFG

Cloud amount and FEWnnn or VVnnn NSC FM051230 15008KT 9999

height of base or SCTnnn or Or BKN020
vertical visibility (C) BKNnnn or VV///
OVCnnn BECMG 1618/1620 8000 NSW
Cloud type (C) CB or TCU -- NSC
BECMG 2306/2308
SCT015CB BKN020

35
 TEMPLATE FOR AERODROME WARNINGS
Key:
M = inclusion mandatory, part of every message; C = inclusion conditional, included
whenever applicable.
Element Detailed content Template Example
Location indicator Location indicator of the nnnn VABB
of the aerodrome
aerodrome(M)
Time of issue (M) Day and time of issue of nnnnnnZ 110300Z
the warning in UTC
Identification of Type of message and AD WRNG [n]n AD WRNG 2
the type of sequence number
message(M)
Validity period Day and time of validity VALID nnnnnn/nnnnnn VALID 110330/110630
(M) period in UTC
IF THE AERODROME WARNING IS TO BE CANCELLED, SEE DETAILS AT THE END OF THE TEMPLATE.

Phenomenon(M)1 Description of phenomenon TC nnnnnnnnnn or TC PHYAN HVY

causing the issuance of the [HVY] TS or SN 25CM
aerodrome warning GR or SFC WSPD 40KT MAX
[HVY] SN [nnCM]2 or 60
[HVY] FZRA or
[HVY] FZDZ or VA TSUNAMI
RIME3 or
[HVY] SS or
[HVY] DS or
SA or
DU or
SFC WSPD nn[n]KT
MAX nn[n]or
SQ or FROST or
TSUNAMI or VA or
Free text up to 32
characters4
Observed or Indication whether the OBS [AT nnnnZ] or OBS AT 1200Z
forecast information is observed and FCST OBS
phenomenon(M) expected to continue, FCST
or forecast
Changes in Expected changes in INTSF or WKN
intensity(C) intensity WKN or
NC
OR
Cancellation of Cancellation of aerodrome CNL AD WRNG [n]n CNL AD WRNG 2
aerodrome warning referring to its nnnnnn/nnnnnn 211230/2115305
warning5 identification

Notes:
1. One phenomenon or a combination there of, in accordance with para 2.3.
2. In accordance with para 2.3.
3. Hoar frost or rime in accordance with para 2.3.
4. In accordance with 2.5.
5. End of the message (as the aerodrome warning is being cancelled.)

36
 TEMPLATE FOR WIND SHEAR WARNINGS
Key:
M = inclusion mandatory, part of every message; C = inclusion conditional, included
whenever applicable.
Note 1. — The ranges and resolutions for the numerical elements included in wind shear warnings
are shown in Table A6-4 of this appendix.
Note 2. — The explanations for the abbreviations can be found in the Procedures for Air Navigation
Services — ICAO Abbreviations and Codes (PANS-ABC, Doc 8400).
Element Detailed content Template Example

Location indicator Location indicator of the nnnn VABB

of the aerodrome aerodrome
(M)
Identification of the Type of message and WS WRNG [n]n WS WRNG 1
type of message sequence number
(M)
Time of origin and Day and time of issue nnnnnn [VALID TL nnnnnn] or 211230 VALID TL 211330
validity period (M)and, where applicable, [VALID nnnnnn/nnnnnn] 221200 VALID 221215/221315
validity period in UTC
IF THE WIND SHEAR WARNING IS TO BE CANCELLED, SEE DETAILS AT THE END OF THE TEMPLATE
Phenomenon (M) Identification of the [MOD] or [SEV] WS IN APCH WS APCH RWY12
phenomenon and its or MOD WS RWY34 WS
location [MOD] or [SEV] WS [APCH] IN CLIMB-OUT MBST
RWYnnn APCH RWY26
or MBST IN CLIMB-OUT
[MOD] or [SEV] WS IN CLIMB-
OUT
or
[MOD] or [SEV] WS CLIMB-
OUT RWYnnn or
MBST IN APCH or
MBST [APCH] RWYnnn
or
MBST IN CLIMB-OUT or
MBST CLIMB-OUT RWYnnn
Observed, reported Identification whether REP AT nnnn nnnnnnnn or REP AT 1510 B747
or forecast the phenomenon is OBS [AT nnnn] or OBS AT 1205 FCST
phenomenon (M) observed or reported FCST
and expected to
continue or forecast
Details of the Description of SFC WIND: nnn/nnKT SFC WIND: 320/10KT
phenomenon (C)1 phenomenon causing the nnnM(nnnFT)-WIND: nnn/nnKT 200FT-WIND: 360/25KT
issuance of the wind shear
warning or 30KT ASPEEDL 2NM
nnKT ASPEEDL nnNM FNA FNA RWY13
RWYnn

or
nnKT ASPEEDG nnNM FNA
RWYnn
OR
Cancellation of Cancellation of wind CNL WS WRNG [n]n CNL WS WRNG 1211230/2113303
wind shear warning2 shear warning referring to nnnnnn/nnnnnn
its identification
Note.
1. Additional provisions as 6.2.3.(Annex 3)
2. End of the message (as the wind shear warning is being cancelled).

37
 TEMPLATE FOR SIGMET MESSAGES
Key:
M = inclusion mandatory, part of every message;
C= inclusion conditional, included wherever applicable.

Elements as Detailed contents Templates Examples

specified
SIGMET
Location ICAO location Nnnn VECF
indicators of indicator of the ATS VOMF
FIR(M) unit serving the FIR VIDF
to which the VABF
SIGMET
refers (M)
Identification Message SIGMET (nn)n SIGMET 5
(M) identification and
sequence number (M)

Validity period Date-time groups VALID nnnnnn/nnnnnn VALID 221215/221600

(M) indicating the period VALID 101520/101800
of validity in VALID 251600/252200
UTC(M)
Location indicator Location indicator of nnnn -- VECC ---
of MWO VOMM ---
MWO (M) originating the VIDP ---
message with a VABB ---
separating hyphen
(M)
Name of FIR Location indicator nnnn nnnnnnnnnn FIR VECF KOLKATA FIR
and name of the FIR VOMF CHENNAI FIR
for which the VIDF DELHI FIR
SIGMET is VABF MUMBAI FIR
issued(M)

38
Phenomena (M) Description of OBSC TS (GR) SEV TURB
phenomenon causing EMBD TS (GR) FRQ TS OBSC
the issuance of FRQ TS (GR) SQL TSGR EMBD
SIGMET (C) TS (GR) TSGR
*TC GLORIA
TC nnnnnnnnnn or NN 6 *[Fictitious name]
TC NN
SEV TURB *VA ERUPTION
SEV ICE MT ASHVAL PSN
SEV ICE (FZRA) S15
SEV MTW E073 VA CLD SEV
ICE RDOACT CLD
HVY DS *[Fictitious location]
HVY SS

(VA ERUPTION)
[MT] [nnnnnnnnnn]
PSN
Nnn(nn) or Snn(nn)
Ennn(nn) or Wnnn(nn)) VA
CLD
RDOACT CLD
Observed or Indication whether the OBS (AT nnnnZ) OBS AT 1210Z
forecast information is observed FCST [AT nnnnZ] OBS
phenomena (M) and FCST AT 1815Z
expected to
continue, or forecast
(M)
Location (C)7 Location (referring to Nnn(nn) Wnnn(nn) or S OF N54
latitude and Nnn(nn) Ennn(nn) or N OF N50
longitude (in degrees Snn(nn) Wnnn(nn) or N2020 W07005
and minutes) or Snn(nn) Ennn(nn) or N AT YUSB3 N2706
locations or OF Nnn(nn) or W07306
geographic features S OF Nnn(nn) or N
well-known OF Snn(nn) or S N48 E010
internationally) OF Snn(nn) or
(AND) N OF N1515 AND
W OF Wnnn (nn) or E W OF E13530
OF Wnnn (nn) or W
OF Ennn (nn) or E OF W OF E 1554
Ennn (nn)
or
N OF LINE S2520
(N OF, NE OF, E OF, SE OF, S
W11510-S2520
OF, SW OF, W OF, NW OF)
W12010
(LINE) Nnn(nn) or Snn(nn)
WI N6030 E02550 –
Wnnn(nn) or Ennn(nn) –
N6055 E02500 – N6050
Nnn(nn) or Snn(nn)
E02630
Wnnn(nn) or Ennn(nn)

39
 or
(N OF, NE OF, E OF, SE OF,
S OF, SW OF, W OF,
NW OF, AT) nnnnnnnnnnnn or
WI Nnn(nn) or Snn(nn) [WI-within]
Wnnn(nn) or Ennn(nn) –
Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn(nn) –
(Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn(nn) –
(Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn(nn))

Level (C)7 Flight level or [SFC/]FLnnn or FL 180

altitude and extent [SFC/]nnnnM (or FL050/080
(C) 3 [SFC/]nnnnFT) or TOP FL390
FLnnn/nnn or TOP FLnnn or SFC/FL070
[TOP] ABV FLnnn TOP ABV FL100
FL310/450
or1
CB TOP (ABV) FLnnn WI CB TOP FL500 WI
nnnKM OF CENTRE 270KM OFCENTRE
(or CB TOP (ABV) FLnnn WI (CB TOP FL500 WI
nnnNM OF CENTRE) or 150NM OF CENTRE)
CB TOP (BLW) FLnnn WI
nnnKM OF CENTRE FL310/350 APRX
(or CB TOP (BLW) FLnnn 220KM BY 35KM
WI nnnNM OF CENTRE)
FL390
or2
FLnnn/nnn (APRX nnnKM
BY nnnKM)
(nnKM WID£ LINE4 BTN
(nnNM WID LINE BTN))
(Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn(nn)
- Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn(nn)
(-Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn(nn))
(-Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn (nn)))
(or FLnnn/nnn (APRX
nnnNM BY nnnNM)
(Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn(nn)
-Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn(nn)
(- Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn(nn))

40
 (-Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn(nn))))

[WID£ - width]
Movement or Movement or MOV N (nnKMH) or MOV MOV E 40KMH
expected expected movement NNE [nnKMH] or (MOV E 20KT)
movement (C)7 (direction and speed) MOV NE (nnKMH) or MOV
with reference to one of ENE [nnKMH] or MOV E MOV SE
the sixteen points of (nnKMH) or MOV ESE STNR
compass, or stationary [nnKMH] or
(C) MOV SE (nnKMH) or MOV
SSE [nnKMH] or
MOV S (nnKMH) or MOV
SSE [nnKMH] or
MOV SW (nnKMH) or MOV
WSW [nnKMH] or
MOV W (nnKMH) or MOV
WNW [nnKMH] or
MOV NW (nnKMH) or MOV
NNW [nnKMH]
(or MOV N (nnKT) or MOV
NNE [nnKT] or
MOV NE (nnKT) or MOV
ENE [nnKT] or
MOV E (nnKT) or MOV ESE
[nnKT] or
MOV SE (nnKT) or MOV
SSE [nnKT] or
MOV S (nnKT) or MOV SSW
[nnKT] or
MOV SW (nnKT) or MOV
WSW [nnKT] or
MOV W (nnKT) or MOV
WNW [nnKT] or
MOV NW (nnKT) or MOV
NNW [nnKT]) or
STNR
Changes in Expected changes in INTSF or WKN or NC WKN
intensity (C)7 intensity (C)
Forecast Forecast position of FCST nnnnZ TC CENTRE FCST 2200Z TC
position (C) 3,7 volcanic ash cloud or Nnn(nn) or Snn(nn) CENTRE N2740
the center of the TC at Wnnn(nn) or Ennn(nn) W07345
the end of the validity or
period of the SIGMET FCST nnnnZ VA CLD APRX FCST 1700Z VA CLD
message (C) (nnKM WID LINE BTN APRX S15 E075 – S15
(nnNM WID LINE BTN)) E081 –
Nnn(nn) or Snn(nn) S17 E083 –
Wnnn(nn) or Ennn(nn) S18 E079 –
– Nnn(nn) or Snn(nn) S15 E075
Wnnn(nn) or Ennn(nn)

41
 (– Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn(nn))
(– Nnn(nn) or Snn(nn)
Wnnn(nn) or Ennn(nn))
[AND] 8
Cancellation of Cancellation of CNL SIGMET (nn)n CNL SIGMET 2
SIGMET (C) 5 SIGMET referring to its nnnnnn/nnnnnn or 101200/1016005
identification CNL SIGMET
(nn) n nnnnnn/nnnnnn (VA CNL SIGMET 3
MOV TO nnnn FIR) 251030/251430 VA MOV
TO *YUDO FIR5
*[Fictitious location]

Notes:
1. Only for SIGMET messages for tropical cyclones.
2. Only for SIGMET messages for volcanic ash.
3. Only for SIGMET messages for volcanic ash cloud and tropical cyclones.
4. A straight line between two points drawn on a map in the Mercator projection or a straight
line between two points which crosses lines of longitude at a constant angle.
5. End of the message (as the SIGMET message is being cancelled)
6. Used for unnamed tropical cyclones
7. In the case of the same phenomenon covering more than one area within the FIR, these
elements can be repeated, as necessary.
8. To be used for two volcanic ash clouds or two centers of tropical cyclones simultaneously
affecting the FIR concerned.

Notes:
Severe icing and severe turbulence (SEV ICE, SEV TURB) associated with thunderstorms,
cumulonimbus clouds or tropical cyclones should not be included.

42
TEMPLATE FOR MET-T4

43
44
45
TEMPLATE FOR MET-T3

46
47
 TEMPLATE FOR AREA / LOCAL FORECAST
India Meteorological Department
METEROROLOGICAL OFFICE: VXXX AIRPORT

LOCAL / AREA FORECAST FOR VXXX AND 100 NM AROUND

From 0600 hours UTC 2010-10-26 date

Till 1400 hours UTC 2010-10-26 date

Time of Origin: 2010-10-26 hours 0530 UTC

SURFACE WIND: 020/10KT MAX20 BECMG 11/13 VRB/02KT

UPPER WIND:

16000M 100 / 15 -78 4500M 050 / 10 +03

13500M 120 / 20 -68 3000M 020 / 10 +10
12000M 110 / 20 -55 2100M 050 / 05 +15
10500M 090 / 20 -43 1500M 050 / 05 +20
9000M 070 / 15 -32 900M 020 / 05 +25
7500M 070 / 20 -15 600M 020 / 05 +27
6000M 070 / 15 -04 300M 020 / 05 +28

WEATHER: HZ TEMPO 09 / 14 MOD TSRA (.) TEMPO 09/14 SEV TURB AND MOD ICING IN CB

VISIBILITY: 4000M IN HZ TEMPO 09 / 14 3000M IN MOD TSRA

SCT SC 450 M BKN AC 2400 M TEMPO 09 / 14

CLOUD: 600 2700
BKN ST 240 M SCT SC 360 M ISOL CB 900 M
540 7000

FREEZING LEVEL: 4800M

ADDITIONAL NOTES: TEMPO 09 / 14 SEV TURB AND MOD ICING IN CB

WARNING: VISIBILITY LIKELY 4000M IN HZ AND 3000M IN MOD TSRA BETWEEN 09/14 MOD TSRA LIKELY
BETWEEN 09/14 WHEN LOW CLOUD BASE 240 M WITH 5 OKTA OR MORE LIKELY.

WARNING FOR LIGHT AIRCRAFT : WIND SPEED MAY REACH 20KTS IN GUST WITH DIRECTION FROM 020

Sunrise: 27/ 0643EF

Sunset: 26/ 1729EF
Moonrise: 27 / 0834EF
Moonset: 26/ 1841EF
Phase of Moon:
Issued at: 0530 hrs. UTC 2010-10-26

“All heights are above M.S.L.”

Meteorological Office

48
 TEMPLATE FOR OUTLOOK FOR LOW VISIBILITY PROCEDURE
India Meteorological Department

Reference Paragraph 11b of Page 24 of AIP India Supplement 32/2007

To be issued only when,

(1) RVR of Operating Runway is less than 1200 m and visibility/RVR is forecasted to
deteriorate to 800 m or less and/or cloud ceiling is 400 ft and is forecasted to fall to 200 ft or less;
(2) Both Transmissometer (TDZ and MID) of Operating Runway are serviceable.

Date: 05/12/2019 Time of Origin: 0115 UTC

Visibility: 1000 m

RVR Runway 01R: TDZ: 1100 m

MID: 1000 m
RVR Runway 19L: TDZ: 1100 m
MID: 1000 m

Cloud Ceiling:

Trend: BECMG 0800 MIFG

Any other pertinent information:-

To (1) WSO:
(2) D.O. Tower:

Signature of D.O.Met (with date and time)

49
 TEMPLATE FOR ADVISORY MESSAGE
India Meteorological Department
Reference Paragraph 11b of Page 24 of AIP India Supplement 32/2007

To be issued only when,

(1) RVR of operating runway is likely to fall below 800 m and/or cloud ceiling is likely to
fall to 200 ft or less within next two hours;
(2) Both Transmissometer (TDZ and MID) of operating runway are serviceable.

Date: 05/12/2019 Time of Origin: 0115 UTC

Visibility: 0900 m

RVR Runway 01R: TDZ: 1000 m

MID: 1000 m
RVR Runway 19L: TDZ: 1000 m
MID: 1000 m
Cloud Ceiling:

Trend: BECMG 0700 MIFG

Any other pertinent information:-

To (1) WSO:
(2) D.O. Tower:

Signature of D.O.Met (with date and time)

50
 Appendix - V
ICAO ABBREVIATIONS
AAL Above Aerodrome Level LOC Local Or Locally Or Location Or
Located
ABT About LONG Longitude
ABV Above LV Light And Variable
AC Altocumulus LVL Level
ACC Area Control Centre LYR Layer Or Layered
ACFT Aircraft MAR March
ACT Active Or Activated Or MAX Maximum
Activity
ADDITIONAL Additional Meteorological MAY May
Information
AGL Above Ground Level METAR Aviation Local Routine Report
AGN Again MI Shallow
AIREP Air- Report MIFG Shallow Fog
ALT Altitude MIN Minutes
ALTN Alternate(Aerodrome) MNM Minimum
AMD Amend Or Amended MOD Moderate
AMSL Above Mean Sea Level MON Monday
AND And MOV Move Or Moving Or Movement
APR April MS Minus
APRX Approximate Or MSL Mean Sea Level
Approximately
ARFOR Area Forecast MT Mountain
AS Altostratus MTW Mountain Waves
AT At (Followed By Time) MWO Meteorological Watch Office
ATC Air Traffic Control N North Or Northern Latitude
ATIS Automatic Terminal NC No Change
Information Service
AUG August NE North East
AVG Average NM Nautical Miles
BASE Cloud Base NNE North North East
BC Patches NNW North North West
BCFG Fog Patches NOSIG No Significant Change
BFR Before NOV November
BKN Broken NS Nimbostratus
BL Blowing NSC Nil Significant Cloud
BLO Below Clouds NSW No Significant Weather
BLSN Blowing Snow NW North-West
BLW Below NW North West

51
BR Mist OBS Observe Or Observed Or
Observation
BTL Between Layers OBSC Obscure Or Obscured Or
Obscuring
BTN Between OCNL Occasional Or Occasionally
BY By OCT October
C Degree Celsius(Centigrade) OF Of (Place)
CAT Clear Air Turbulence OPMET Operational Meteorological
(Information)
CAVOK Visibility, Cloud And OTLK Outlook
Present Weather Better
Than Prescribed Values Or
Conditions
CB Cumulonimbus OVC Overcast
CC Cirrocumulus PO Dust/Sand Whirls
CI Cirrus PROB Probability
CLD Cloud PROV Provision
CNL Cancel Or Cancelled PS Plus
CNS Continuous PSN Position
COND Condition QFE Atmospheric Pressure At
Aerodrome Elevation
CONT Continue Or Continued QNH Altimeter Subscale When On
The Ground
COR Correct Or Correction Or RA Rain
Corrected
COT At The Cost RAPID Rapid Or Rapidly
COV Cover Or Covered Or RASH Rain Showers
Covering
CS Cirrostratus RASN Rain And Snow Or Showers Or
Rain And Snow
CTA Control Area RDOACT Radioactive
CU Cumulus RE Recent
CUF Cumuliform REF Reference To Or Referred To
DEC December RMK Remark
DEG Degrees ROBEX Regional OPMET Bulletin
Exchange
DEV Deviation Or Deviating ROFOR Route Forecast
DIF Diffuse RTE Route
DIST Distance RVR Runway Visual Range
DP Dew Point RWY Runway
DPT Depth S South Or Southern Latitude
DR Low Drifting SAT Saturday
DRG During SC Stratocumulus
DS Dust Storm SCT Scattered
DTRT Deteriorate Or Deteriorating SE Southeast

52
DU Widespread Dust SEV Severe
DUC Dense Upper Cloud SFC Surface
DUR Duration SG Snow Grains
DZ Drizzle SH Showers
E East Or Eastern SIGMET Information Concerning En-Route
Weather Phenomena Which May
Affect The Safety Of Aircraft
Operations
ELEV Elevation SIGWX Significant Weather
EMBD Embedded In A Layer SIMUL Simultaneous Or Simultaneously
ENE East North East SKC Sky Clear
ENR En-Route SLW Slow
ERUPTION Volcanic Eruption SN Snow
ESE East South East SNSH Snow Showers
EST Estimate Or Estimated SPECI Aviation Local Special Report
ETD Expected Time Of SQ Squall
Departure
EXC Except SQL Squall Line
EXP Expect Or Expected Or SS Sandstorm
Expecting
EXTD Extend Or Extending SSE South South East
FBL Light SSW South South West
FC Funnel Cloud ST Stratus
FCST Forecast STF Stratiform
FEB February STN Station
FEW Few STNR Stationary
FIC Flight Information Centre SUN Sunday
FIR Flight Information Region SW South West
FL Flight Level T Temperature
FLUC Fluctuating Or Fluctuation TAF Aerodrome Forecast
Or Fluctuated
FM From TC Tropical Cyclone
FREQ Frequency TCU Towering Cumulus
FRI Friday TDO Tornado
FRQ Frequent TEMPO Temporary Or Temporarily
FST First TEND Trend Or Tending To
FST Hours THU Thursday
FU Smoke TIL Until
FU Hurricane TO To (Place)
FZ Freezing TOP Cloud Top
FZ Heavy TROP Tropopause
FZDZ Freezing Drizzle TS Thunderstorm (without
Precipitation)

53
FZFG Freezing Fog TSGR Thunderstorm With Hail
FZRA Freezing Rain TSSS Thunderstorm With Dust Storm
Or Sandstorm
GND Ground Temperature TUE Tuesday
GR Hail Or Soft Hail TURB Turbulence
GRADU Gradual Or Gradually UTC Coordinated Universal Time
GRID Processed Meteorological VA Volcanic Ash
Data In The Form Of Grid
Point Values
HVY Heavy VALID Valid
HZ Haze VIS Visibility
ICE Icing VOLMET Meteorological Information For
Aircraft In Flight
IMPR Improve Or Improving VRB Variable
INC In Cloud W West Or Western Longitude
INTSF Intensify Or Intensifying WAFC World Area Forecast Centre
INTST Intensity WDSPR Wide Spread
ISOL Isolated WED Wednesday
JAN January WI Within
JTST Jet Stream WID Width
JUL July WKN Weaken Or Weakening
JUN June WNW West North West
KM Kilometres WRNG Warning
KMH Kilometre Per Hour WS Wind Shear
KT Knots WSW West South West
LAT Latitude WTSPT Waterspout
LEN Length WX Weather
LINE Line Z Coordinated Universal Time

54