091 VFR COMMUNICATIONS

G LONGHURST 1999 All Rights Reserved Worldwide

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Produced and Published by the
CLICK2PPSC LTD
EDITION 2.00.00 2001
This is the second edition of this manual, and incorporates all amendments to previous editions, in
whatever form they were issued, prior to July 1999.
EDITION 2.00.00 1999,2000,2001 G LONGHURST
The information contained in this publication is for instructional use only. Every effort has been made to ensure
the validity and accuracy of the material contained herein, however no responsibility is accepted for errors or
discrepancies. The texts are subject to frequent changes which are beyond our control.
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TABLE OF CONTENTS
G LONGHURST 1999 All Rights Reserved Worldwide
Definitions
General Operating Procedures
Radar Procedural Phraseology
Relevant Weather Information Terms
Action Required to be Taken in Case of
Communication Failure
Distress and Urgency Procedures
General Principles of VHF Propagation and
Allocation of Frequencies
091 VFR Communications
G LONGHURST 1999 All Rights Reserved Worldwide
Definitions
Commonly Used Abbreviations
Direction Finding
Categories of Messages
Definitions
Chapter 1 Page 1 G LONGHURST 1999 All Rights Reserved Worldwide
1Definitions
1. The student should be familiar with the following definitions and abbreviations:
Advisory Area. A designated area where air traffic advisory service is available.
Advisory Route. A designated route along which air traffic advisory service is available.
Aerodrome. Any area of land or water designed, equipped, set apart or commonly used for
affording facilities for the landing and departure of aircraft.
Aerodrome Control Service. Air traffic control service for aerodrome traffic.
Aerodrome control radio station. A station providing radio communication between an
aerodrome control tower and aircraft or mobile aeronautical stations.
Aerodrome Traffic. All traffic on the manoeuvring area of an aerodrome and all aircraft
operating in the vicinity of an aerodrome.
Aerodrome Traffic Circuit. The specified flight path to be flown by aircraft operating in the
vicinity of an aerodrome.
Aerodrome Traffic Zone. Airspace of defined dimensions established around an aerodrome for
the protection of aerodrome traffic.
Definitions
Chapter 1 Page 2 G LONGHURST 1999 All Rights Reserved Worldwide
Aeronautical broadcasting service. A broadcasting service intended for the transmission of
information relating to air navigation.
Aeronautical fixed circuit. A circuit forming part of the Aeronautical Fixed Service (AFS).
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 station. A station in the aeronautical fixed service.
Aeronautical fixed telecommunication network circuit. A circuit forming part of the
Aeronautical Fixed Telecommunication Network (AFTN).
Aeronautical Fixed Telecommunication Network (AFTN). A world-wide 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 he same or compatible
communications characteristics.
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 radio navigation service. A radio navigation service intended for the benefit and
for the safe operation of aircraft.
Definitions
Chapter 1 Page 3 G LONGHURST 1999 All Rights Reserved Worldwide
Aeronautical telecommunication log. A record of the activities of an aeronautical
telecommunication station.
Aeronautical telecommunication station. A station in the aeronautical telecommunication
service.
Aeronautical Station. A land station in the aeronautical mobile service. In certain instances, an
aeronautical station may be placed board a ship or an earth satellite.
AFTN communication centre. An AFTN station whose primary function is the relay or
retransmission of AFTN traffic from (or to) a number of other AFTN stations connected to it.
AFTN destination station. An AFTN station to which messages and/or digital data are
addressed for processing for delivery to the addressee.
AFTN origin station. An AFTN station where messages and/or digital data are accepted for
transmission over the AFTN.
AFTN station. A station forming part of the Aeronautical Fixed Telecommunication Network
(AFTN) and operating as such under the authority or control of a State.
Airborne Collision Avoidance System. An aircraft system based on SSR transponder signals
which operates independently of ground-based equipment to provide advice to the pilot on potential
conflicting aircraft that are equipped with SSR transponders.
Air-ground control radio station. An aeronautical telecommunication station having primary
responsibility for handling communications pertaining to the operation and control of aircraft in a
given area.
Definitions
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Air-report. A report from an aircraft in flight prepared in conformity with requirements for
position, and operational and/or meteorological reporting.
Air-to-ground communication. One-way communication from aircraft to stations or locations
on the surface of the earth.
Aircraft Station. A mobile station in the aeronautical mobile service on board an aircraft.
Air-ground Communications. Two-way communication between aircraft and stations or
locations on the surface of the earth.
AIRPROX. The code word used in an air traffic incident report to designate aircraft proximity.
Air Traffic. All aircraft in flight or operating on the manoeuvring area of an aerodrome.
Air Traffic Control Clearance. Authorisation for an aircraft to proceed under conditions
specified by an air traffic control unit.
Air Traffic Service (ATS). A generic term meaning variously, flight information service, alerting
service, air traffic advisory service, air traffic control service, approach control service or aerodrome
control service.
Airway. A control area or part of a control area established in the form of a corridor equipped
with radio navigation aids.
Altitude. The vertical distance of a level, a point or an object considered as a point, measured
from mean sea level.
Approach Control Service. Air traffic control service for arriving or departing controller flights.
Definitions
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Area Control Centre. A term used in the United Kingdom to describe a unit providing en-route
air traffic control services.
ATS direct speed circuit. An Aeronautical Fixed Service (AFS) telephone circuit, for direct
exchange of information between Air Traffic Services (ATS) units.
Automatic Terminal Information Service (ATIS) (UK). The provision of current, routine
information to arriving and departing aircraft by means of continuous and repetitive broadcasts
throughout the day or a specified portion of the day.
Base Turn. A turn executed by the aircraft during the initial approach between the end of the
outboard track and the beginning of the intermediate or final approach track. The tracks are not
reciprocal.
Blind Transmission. A transmission from one station to another station in circumstances where
two-way communication cannot be established but where it is believed that the called station is able
to receive the transmission.
Broadcast. A transmission of information relating to air navigation that is not addressed to a
specific station or stations.
Clearance Limit. The point to which an aircraft is granted an air traffic control clearance.
Communication centre. An aeronautical fixed station which relays or retransmits
telecommunication traffic from (or to) a number of other aeronautical fixed stations directly
connected to it.
Definitions
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Control Area. A controlled airspace extending upwards from a specified limit above the surface
of the earth.
Controlled Airspace. An airspace of defined dimensions within which air traffic control service
is provided to IFR flights and to VFR flights in accordance with the airspace classification.
Control Zone. A controlled airspace extending upwards from the surface of the earth to a
specified upper limit.
Cruising Level. A level maintained during a significant portion of a flight.
Decision Altitude/Height. A specified altitude/height in a precision approach at which a missed
approach must be initiated if the required visual reference to continue the approach to land has not
been established.
Duplex. A method in which telecommunication between two stations can take place in both
directions simultaneously.
Elevation. The vertical distance of a point or level on, or affixed to, the surface of the earth
measured from mean sea level.
Estimated Time of Arrival. The time at which the pilot estimates that the aircraft will be over a
specific location.
Expected Approach Time. The time at which ATC expects that an turning aircraft, following a
delay, will leave the holding point to complete its approach for landing.
Definitions
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Flight Information Centre. A unit established to promote flight information service and alerting
service.
Flight Level. A surface of constant atmospheric pressure, which is related to a specific pressure
datum, 1013.2 mb, and is separated from other such surfaces by specific pressure intervals.
Flight Plan. Specified information provided to air traffic services units, relative to an intended
flight of an aircraft. Flight Plans fall into two categories: Full Flight Plans and Abbreviated Flight
Plans.
General Air Traffic. Flights operating in accordance with civil air traffic procedures.
Ground-to-air communication. One-way communication from stations or locations on the
surface of the earth to aircraft.
Headings. The direction in which the longitudinal axis of an aircraft is pointed, usually expressed
in degrees from North (true, magnetic, compass or grid).
Height. The vertical distance of a level, a point, or an object considered as a point measured from
a specified datum.
Holding Point. A specified location, identified by unusual or other means in the vicinity of which
the position of an aircraft in flight is maintained in accordance with ATC clearance.
IFR Flight. A flight conducted in accordance with the instrument flight rules.
Definitions
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Instrument Meteorological Conditions (IMC). Meteorological conditions expressed in terms
of visibility, horizontal and vertical distance from cloud, less than the minima specified for visual
meteorological conditions.
Interpilot air-to-air communication. Two-way communication on a designated air-to-air
channel to enable aircraft engaged in flights over remote and oceanic areas out of range of VHF
ground stations to exchange necessary operational information and to facilitate the resolution of
operation problems.
Known Traffic. Traffic, the current flight details and intentions of which are known to the
controller concerned through direct communication or co-ordination.
Level. A generic term relating to the various position of an aircraft in flight and meaning
variously, height, altitude or flight level.
Manoeuvering Area. That part of an aerodrome to be used for the take-off, landing and taxiing
of aircraft excluding aprons.
Minimum Descent Altitude/Height. An altitude/height in a non-precision or circling approach
below which descent may not be made without visual reference.
Missed Approach Point. The point in an instrument approach procedure at or before which the
prescribed missed approach procedure must be initiated in order to ensure that the minimum
obstacle clearance is not infringed.
Missed Approach Procedure (MAP). The procedure to be followed if the approach cannot be
continued.
Definitions
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Mobile surface station. A station in the aeronautical telecommunication service, other than an
aircraft station, intended to be used while in motion or during halts at unspecified points.
Movement Area. The manoeuvering area and the aprons.
Network station. An aeronautical station forming part of a radiotelephony network.
Non-network Communications. Radiotelephony communications conducted by a station of
the aeronautical mobile service, other than those conducted as part of a radiotelephony.
Procedure Turn. A manoeuvre in which a turn is made away from a designated track followed by
a turn in the opposite direction to permit the aircraft to intercept and proceed along the reciprocal of
the designated track.
Radar Approach. An approach, executed by an aircraft, under the direction of a radar controller.
Radar Contact. The situation which exists when the radar blip or radar position symbol of a
particular aircraft is seen and identified on a radar display.
Radar Identification. The process of correlating a particular radar blip or radar position symbol
with a specific aircraft.
Radar Vectoring. Provision of navigational guidance to aircraft in the form of specific headings,
based on the use of radar.
Radio direction-finding station. A radio station intended to determine only the direction of
other stations by means of transmissions from the latter.
Definitions
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Radiotelephony network. A group of radiotelephony aeronautical stations which operate on
and guard frequencies from the same family and which support each other in a defined manner to
ensure maximum dependability of air-ground communications and dissemination of air-ground
traffic.
Readback. A procedure whereby the receiving station repeats a received message or an
appropriate part thereof back to the transmitting station so as to obtain confirmation of correct
reception.
Regular station. A station selected from those forming an en-route air-ground radiotelephony
network to communicate with or to intercept communications from aircraft in normal conditions.
Reporting Point. A specified geographical location in relation to which the position of an aircraft
can be reported.
Runway. A defined rectangular area on a land aerodrome prepared for the landing and take-off
aircraft.
Runway Visual Range. The range over which the pilot of an aircraft on the centre line of a
runway can expect to see the runway surface markings, or the lights delineating the runway or
identifying its centre line.
Signal Area. An area on an aerodrome used for the display of ground signals.
SIGMET information. Information issued by a meteorological watch office concerning the
occurance or expected occurance of specified en-route weather phenomena which may affect the
safety of aircraft operations.
Definitions
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Simplex. A method in which telecommunication between two stations takes place in one direction
at a time.
Telecommunication. Any transmission, emission, or reception of signs, signals, writing, images
and sounds or intelligence of any nature by wire, radio, optical or other electromagnetic systems.
Terminal Control Area. A control area normally established at the confluence of airways in the
vicinity of one or more major aerodromes.
Threshold. The beginning of that portion of the runway useable for landing.
Traffic Alert and Collision Avoidance System. See ACAS.
Tributary station. An aeronautical fixed station that may receive or transmit messages and/or
digital data but which does not relay except for the purpose of serving similar stations connected
through it to a communication centre.
VFR Flight. A flight conducted in accordance with the visual flight rules.
Visual Meteorological Conditions (VMC). Meteorological conditions expressed in terms of
visibility, horizontal and vertical distance from cloud, equal to or better than specified minima.
Commonly Used Abbreviations
2. The abbreviations annotated with an asterisk are normally spoken as complete words. The
remainder are normally spoken using the constituent letters rather than the spelling alphabet.
Definitions
Chapter 1 Page 12 G LONGHURST 1999 All Rights Reserved Worldwide
Categories of Message
A
aal Above Aerodrome Level
ACAS* (A-kas) Airborne Collision Avoidance System (see TCAS)
ACC Area Control Centre
ADF Automatic Direction-Finding Equipment
ADR Advisory Route
ADT Approved Departure Time
AFIS Aerodrome Flight Information Service
AFTN Aeronautical Fixed Telecommunication Network
agl Above Ground Level
AAIB Air Accident Investigation Branch
AIC Aeronautical Information Circular
AIRPROX* Aircraft Proximity (replaces Airmiss/APHAZ)
AIP Aeronautical Information Publication
AIRAC Aeronautical Information Regulation and Control
AIS Aeronautical Information Services
amsl Above Mean Sea Level
ANO Air Navigation Order
Definitions
Chapter 1 Page 13 G LONGHURST 1999 All Rights Reserved Worldwide
ATA Actual Time of Arrival
ATC Air Traffic Control (in general)
ATD Actual Time of Departure
ATIS* Automatic Terminal Information Service
ATS Air Traffic Service
ATSU Air Traffic Service Unit
ATZ Aerodrome Traffic Zone
C
CAA Civil Aviation Authority
CAVOK* Visibility, cloud and present weather better than prescribed values or
conditions (CAVOK pronounced Cav-okay)
CTA Control Area
CTR Control Zone
D
DAAIS* Danger Area Activity Information Service (DAAIS pronounced DAY-ES)
DACS* Danger Area Crossing Service
DF Direction Finding
DME Distance Measuring Equipment
DR Dead Reckoning
E
Definitions
Chapter 1 Page 14 G LONGHURST 1999 All Rights Reserved Worldwide
EAT Expected Approach Time
ETA Estimated Time of Arrival
ETD Estimated Time of Departure
F
FAF Final Approach Fix
FIR Flight Information Region
FIS Flight Information Service
FL Flight Level
Ft Foot (feet)
G
GAT General Air Traffic
GMC Ground Movement Control
H
H24 Continuous day and night service (H24 pronounced Aitch Twenty Fower)
HF High Frequency (3 to 30 MHz)
HJ Sunrise to Sunset
I
IAF Initial Approach Fix
ICAO* International Civil Aviation Organisation
Definitions
Chapter 1 Page 15 G LONGHURST 1999 All Rights Reserved Worldwide
IF Intermediate Approach Fix
IFR Instrument Flight Rules
ILS Instrument Landing System
IMC Instrument Meteorological Conditions
IRVR Instrumented Runway Visual Range
K
kg Kilogramme (s)
km Kilometre (s)
kt Knot (s)
M
MAPt Missed Approach Point
MATZ* Military Aerodrome Traffic Zone
MDA/H Minimum Descent Altitude/Height
MEDA* Military Emergency Diversion Aerodrome
MET* Meteorological or Meteorology
METAR* Routine aviation aerodrome weather report
MLS Microwave Landing System
MNPS Minimum Navigation Performance & Specification
mb Millibars
Definitions
Chapter 1 Page 16 G LONGHURST 1999 All Rights Reserved Worldwide
N
NATS National Air Traffic Service
NDB Non-Directional Radio Beacon
NOTAM A notice 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.
O
OAC Oceanic Area Control Unit
OCA Oceanic Control Area
OCA/H Obstacle Clearance Altitude/Height
P
PAPIS* Precision Approach Path Indicating System (PAPIS pronounced Pa-pee)
PAR Precision Approach Radar
Q
QDM Magnetic heading (zero wind) (Sometimes employed to indicate magnetic
heading of a runway)
QDR Magnetic Bearing
QFE The observed pressure at a specified datum (usually aerodrome or runway
threshold elevation) corrected for temperature
Definitions
Chapter 1 Page 17 G LONGHURST 1999 All Rights Reserved Worldwide
QFF Meteorologists determine a mean sea level pressure which is more accurate
than the QNH by reducing the QFE to mean sea level using ambient rather
than standard atmosphere temperature lapse rates. The MSL pressure thus
obtained is termed the QFF.
QGH Ground interpreted letdown procedure using DF equipment.
QNE When flying above the transition altitude it is normal to set 1013mb on the
altimeter subscale and maintain a flight level. When 1013 is set on the
subscale, the height shown on the altimeter when the aircraft is on the
ground is known as the QNE value.
QNH The QFE reduced to mean sea level (MSL) pressure using the standard
atmosphere lapse rate. The pressure altimeter is calibrated to the standard
atmosphere, and so when QNH is set on the altimeter subscale the
instrument indicates the airfield elevation at the airfield datum point. We
talk above of reducing QFE to QNH. It is however a reduction in height
which results in an increase in pressure when changing QFE to QNH for an
airfield which is above MSL.
QTE True Bearing
R
RA Resolution Advisory (see TCAS)
RCC Rescue Co-ordination Centre
RPS Regional Pressure Setting
RTF Radiotelephone/Radiotelephony
RVR Runway Visual Range
Definitions
Chapter 1 Page 18 G LONGHURST 1999 All Rights Reserved Worldwide
S
SAR Search and Rescue
SID* Standard Instrument Departure
SIGMET* Significant information concerning en-route weather phenomena which may
affect the safety of aircraft operations
SRA Surveillance Radar Approach
SSR Secondary Surveillance Radar
STAR* Standard (instrument) Arrival Route
T
TA Traffic Advisory (see TCAS)
TAF* Terminal Aerodrome Forecast
TCAS* Traffic Alert and Collision Avoidance System (Tee-kas)
TMA Terminal Control Area
U
UAS Upper Airspace
UHF Ultra-High Frequency
UIR Upper Flight Information Region
UTA Upper Control Area
UTC Co-ordinated Universal Time
V
Definitions
Chapter 1 Page 19 G LONGHURST 1999 All Rights Reserved Worldwide
Direction Finding
3. Direction-finding stations work either singly or in groups of two or more stations under the
direction of a main direction-finding station.
4. A direction-finding station working alone can only determine the direction of an aircraft in
relation to itself.
5. A direction-finding station working alone should give the following, as requested:
(i) True bearing of the aircraft, using the signal QTE or appropriate phrase.
(ii) True heading to be steered by the aircraft, with no wind, to head for the
direction-finding station using the signal QUJ or appropriate phrase.
(iii) Magnetic bearing of the aircraft, using the signal QDR or appropriate phrase.
VASIS* Visual Approach Slope Indicator System (VASIS pronounced Var-zi)
VDF Very High Frequency Direction-Finding Station
VFR Visual Flight Rules
VHF Very High Frequency (30 to 300 MHz)
VMC Visual Meteorological Conditions
VOLMET* Meteorological information for aircraft in flight
VOR VHF Omnidirectional Radio Range
VORTAC* VOR and TACAN combination
Definitions
Chapter 1 Page 20 G LONGHURST 1999 All Rights Reserved Worldwide
(iv) Magnetic heading to be steered by the aircraft with no wind to make for the
station, using the signal QDM or appropriate phrase.
6. When direction-finding stations work as a network to determine the position of an aircraft,
the bearings taken by each station should be sent immediately to the station controlling the direction-
finding network to enable the position of the aircraft to be determined.
7. The station controlling the network should, on request, give the aircraft its position in one of
the following ways:
(i) Position in relation to a point of reference or in latitude and longitude, using
the signal QTF or appropriate phrase.
(ii) True bearing of the aircraft in relation to the direction-finding station or other
specified point, using the signal QTE or appropriate phrase, and its distance
form the direction-finding station or point, using the signal QGE or
appropriate phrase.
(iii) Magnetic heading to steer with no wind, to make for the direction-finding
station or other specified point using the signal QDM or appropriate phrase,
and its distance form the direction-finding station or point, using the signal
QGE or appropriate phrase.
8. Aircraft stations shall normally make requests for bearings, courses or positions, to the
aeronautical station responsible, or to the station controlling the direction-finding network.
9. To request a bearing, heading or position, the aircraft station shall call the aeronautical
station or direction-finding control station on the listening frequency. The aircraft shall then specify
the type of service that is desired by the use of the appropriate phrase or Q signal.
Definitions
Chapter 1 Page 21 G LONGHURST 1999 All Rights Reserved Worldwide
10. An aircraft station requiring a series of bearings or headings, shall call the direction-finding
station concerned, on the appropriate frequency, and request the service by the signal QDL followed
by other appropriate Q signals, except that when the series has commenced, the call signs of the
stations may be omitted if no confusion is likely to arise.
11. As soon as the direction-finding station or group of stations is ready, the station originally
called by the aircraft station shall where necessary request transmission for direction-finding service
or send the appropriate Q signal, and, if necessary, indicate the frequency to be used by the aircraft
station, the number of times the transmission should be repeated, the duration of the transmission
required or any special transmission requirement.
12. In radiotelegraphy, the aircraft shall, after changing it necessary to the new transmitting
frequency, reply by sending its call sign, two dashes of about ten seconds of duration each and then
repeating its call sign, unless some other period has been specified by the direction-finding station.
13. In radiotelephony, an aircraft station which requests a bearing shall end the transmission by
repeating its call sign. If the transmission has been too short for the direction-finding station to
obtain a bearing, the aircraft shall give a longer transmission for two periods of approximately ten
seconds, or alternatively provide such other signals as may be requested by the direction-finding
station.
NOTE:
Certain types of VHF/DF stations require the provision of a modulated signal
(voice transmission) in order to take a bearing.
14. When a direction-finding station is not satisfied with is observations, it shall request the
aircraft station to repeat the transmission.
Definitions
Chapter 1 Page 22 G LONGHURST 1999 All Rights Reserved Worldwide
15. When a heading or bearing has been requested, the direction-finding station shall advise the
aircraft station in the following form:
(i) The appropriate phrase or Q signal.
(ii) Bearing or heading in degrees in relation to the direction-finding station, sent
as three figures.
(iii) Class of bearing except in QDL procedure
(iv) Time of observation, if necessary]
16. When a position has been requested, the direction-finding control station, after plotting all
simultaneously observations, shall determine the observed position of the aircraft and shall advise the
aircraft station in the following form:
(i) The appropriate phrase or Q signal.
(ii) The position.
(iii) Class of position.
(iv) Time of observation.
17. As soon as the aircraft station has received the bearing, heading or position, it shall repeat
back the message for confirmation, or correction, except in QDL procedure.
Definitions
Chapter 1 Page 23 G LONGHURST 1999 All Rights Reserved Worldwide
18. When positions are given by bearing or heading and distance form a known point other than
the station making the report, the reference point shall be an aerodrome, prominent town or
geographic feature. An aerodrome shall be given in preference to other places. When a large city or
town is used as a reference place, the bearing or heading, and the distance given shall be measured
from its centre.
19. When the position is expressed in latitude and longitude, groups of figures for degrees and
minutes shall be used followed by the letter N or S for latitude and the letter E or W for longitude,
respectively. In radiotelephony the words NORTH, SOUTH, EAST or WEST shall be used.
20. According to the estimate by the direction-finding station of the accuracy of the observations,
bearings and positions shall be classified as follows:
Bearings:
Class A - accurate within plus or minus 2 degrees;
Class B - accurate within plus or minus 5 degrees;
Class C - accurate within plus or minus 10 degrees;
Class D - accuracy less than Class C.
NOTE:
The observational characteristics for classification of bearings are given in the
table of Appendix 41 to the current ITU Radio Regulations.
Definitions
Chapter 1 Page 24 G LONGHURST 1999 All Rights Reserved Worldwide
Positions:
Class A - accurate within 9.3km (5 NM);
Class B - accurate within 37km (20 NM);
Class C - accurate within 93km (50 NM);
Class D - accuracy less than Class C.
21. Direction-finding stations shall have authority to refuse to give bearings, heading or positions
when conditions are unsatisfactory or when bearings do not fall within the calibrated limits of the
station, stating the reason at the time of refusal.
NOTE:
Certain MF and HF direction-finding stations are maintained for emergency
and distress use only. The use of these stations, the hours of service, the call
sign, location and frequencies of communication stations, and certain
exceptions to the above procedure are shown in the pertinent publications.
Categories of Messages
22. The categories of messages handled by the aeronautical mobile service are in the following
order of priority.
Definitions
Chapter 1 Page 25 G LONGHURST 1999 All Rights Reserved Worldwide
Distress messages Urgency messages
Communications relating to direction finding
Flight safety messages
Meteorological messages
Flight Regularity messages
}See Distress andUrgency Procedures
Definitions
Chapter 1 Page 26 G LONGHURST 1999 All Rights Reserved Worldwide
Self Assessed Exercise No. 1
QUESTIONS:
QUESTION 1.
Give the name of airspace of defined dimensions established around an aerodrome for the protection
of aerodrome traffic.
QUESTION 2.
Define Approach Control Service.
QUESTION 3.
What is blind transmission?
QUESTION 4.
What is the name given to transmission of information relating to air navigation that is not addressed
to a specific station or stations?
QUESTION 5.
What is ATIS?
QUESTION 6.
What is a MATZ?
Definitions
Chapter 1 Page 27 G LONGHURST 1999 All Rights Reserved Worldwide
QUESTION 7.
What does DAAIS stand for?
QUESTION 8.
What is QFF?
QUESTION 9.
What are the following: a. QTE b. QUJ c. QDR d. QDM?
QUESTION 10.
What is QNE?
QUESTION 11.
State the accuracy of VDF bearings Class A, Class B and Class C.
QUESTION 12.
State the accuracy of VDF-derived positions (nm) Class A, Class B and Class C.
QUESTION 13.
List the categories of message in order of priority.
QUESTION 14.
What is UTA?
Definitions
Chapter 1 Page 28 G LONGHURST 1999 All Rights Reserved Worldwide
QUESTION 15.
What is UIR?
QUESTION 16.
What does HJ mean?
QUESTION 17.
What does MNPS mean?
QUESTION 18.
What is a Control Area?
ANSWERS:
ANSWER 1.
Aerodrome Traffic Zone (ATZ)
091 VFR Communications Chap 1-Definitions
ANSWER 2.
An air traffic control service for arriving or departing controlled flights.
091 Communications-Definitions.
Definitions
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ANSWER 3.
A transmission from one station to another in circumstances where two-way communication cannot
be established but where it is believed that the called station is able to receive the transmission.
091 Chap 1 definitions
ANSWER 4.
Broadcast
091 Chap 1-Definitions
ANSWER 5.
Automatic Terminal Information Service
091 Chap 1-Abbreviations
ANSWER 6.
Military Aerodrome Traffic Zone
091 Chap 1-Abbreviations
ANSWER 7.
Danger Area Activity Information Service.
091 Chap 1 abbreviations
Definitions
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ANSWER 8.
QFE reduced to mean sea level using ambient conditions.
091 Chap 1 abbreviations
ANSWER 9.
True bearing from a station
True heading to a station (no wind)
Magnetic bearing from a station
Magnetic heading to a station (no wind)
091 Chap 1 direction-finding
ANSWER 10.
The altimeter reading when the subscale is set to 1013mb and the aircraft is on the ground.
091 Chap 1 abbreviations
ANSWER 11.
Class A within 2 degrees
Class B within 5 degrees
Class C within 10 degrees
091 Chap 1 page 1-15
Definitions
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ANSWER 12.
Class A within 5nm
Class B within 20nm
Class C within 50nm
091 Chap 1 page 1-15
ANSWER 13.
Distress messages
Urgency messages
Communication relating to direction-finding
Flight safety messages
Meteorological messages
Flight regularity messages
091 Chap 1 page 16
ANSWER 14.
Upper Control Area
091 Chap 1 page 11
Definitions
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ANSWER 15.
Upper Flight Information Region
091 Chap 1 page 11
ANSWER 16.
Sunrise to sunset
091 Chap page 9
ANSWER 17.
Minimum Navigation Performance and Specification
091 Chap 1 page 9
ANSWER 18.
A controlled airspace extending upwards from a specified limit above the surface of the earth
091 Chap 1 page 4
091 VFR Communications
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General Operating Procedures
Transmission of Letters
Transmission of Numbers
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2General Operating Procedures
Transmission of Letters
1. The words in the table below should be used when individual letters are required to be
transmitted. The syllables to be emphasised are underlined.
Letter Word Appropriate Pronunciation
A Alpha AL FAH
B Bravo BRAH VOH
C Charlie CHAR LEE
D Delta DELL TAH
E Echo ECK OH
F Foxtrot FOKS TROT
G Golf GOLF
H Hotel HOH TELL
I India IN DEE AH
J Juliett JEW LEE ETT
K Kilo KEY LOH
L Lima LEE MAH
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Word spelling in radiotelephony. Proper names, service abbreviations and words of which the
spelling is doubtful are spelled out in radiotelephony using the above alphabet.
Transmission of Numbers
2. The syllables to be emphasised are underlined.
M Mike MIKE
N November NO VEM BER
O Oscar OSS CAH
P Papa PAH PAH
Q Quebec KEH BECK
R Romeo ROW ME OH
S Sierra SEE AIR RAH
T Tango TANG GO
U Uniform YOU NEE FORM
V Victor VIK TAH
W Whiskey WISS KEY
X X-ray ECKS RAY
Y Yankee YANG KEE
Z Zulu ZOO LOO
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3. All numbers, except those contained in paragraph (b) shall be transmitted by pronouncing
each digit separately as follows:
(a) When transmitting messages containing aircraft callsigns, altimeter settings, flight
levels, headings, wind speeds/directions, transponder codes and frequencies, each digit
shall be transmitted separately; examples of this convention are as follows:
Numeral or numeral element Latin alphabet representation
0 ZERO
1 WUN
2 TOO
3 TREE
4 FOWER
5 FIFE
6 SIX
7 SEVEN
8 AIT
9 NINER
Decimal DAYSEEMAL
Hundred HUN DRED
Thousand TOUSAND
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(b) All numbers used in the transmission of altitude, height, cloud height, visibility and
runway visual range information which contain whole hundreds and whole thousands
should be transmitted by pronouncing each digit in the number of hundreds or
thousands followed by the word HUNDRED or TOUSAND as appropriate.
Combinations of thousands and whole hundreds should be transmitted by
pronouncing each digit in the number of thousands followed by the word TOUSAND
and the number of hundreds followed by the word HUNDRED; examples of this
convention are as follows:
Number Transmitted as Pronounced as
BAW102 Speedbird One Zero Two SPEEDBIRD WUN ZERO TOO
FL 280 Flight Level Two Eight Zero FLIGHT LEVEL TOO AIT ZERO
190 Degrees One Nine Zero Degrees WUN NINER ZERO DEGREES
15 Knots One Five Knots WUN FIFE KNOTS
122.1 One Two Two Decimal One WUN TOO TOO DAYSEEMAL WUN
6500 Six Five Zero Zero SIX FIFE ZERO ZERO (SQUAWK)
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4. Numbers containing a decimal point shall be transmitted as prescribed above with the
decimal point in appropriate sequence being indicated by the word decimal.
NOTE:
Only the first five figures are used when identifying frequencies separated by
25 kHz.
5. When it is necessary to verify the accurate reception of numbers the person transmitting the
message should request the person receiving the message to read back the numbers.
Number Transmitted as Pronounced as
10 One Zero WUN ZERO
100 One Hundred WUN HUNDRED
2 500 Two Thousand Five Hundred TOO TOUSAND FIFE HUNDRED
11 000 One One Thousand WUN WUN TOUSAND
25 000 Two Five Thousand TOO FIFE TOUSAND
Number Transmitted as Pronounced as
118.1 One One Eight Decimal One WUN WUN AIT DAY SEE MAL WUN
120.375 One Two Zero Decimal Three seven WUN TOO ZERO DAY SEE MAL TREE
SEVEN
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Transmission of Time
6. When transmitting time, only the minutes of the hour are normally required. However, the
hour should be included if there is any possibility of confusion. Time checks should be given to the
nearest minute. Co-ordinated Universal Time (UTC) is to be used at all times, unless specified.
Midnight is given as 2400 hours and constitutes the end of the day. The beginning of the next day is
coincident and is designated as 0000 hours.
Transmitting Technique
7. There are a number of recognised checks that the operator can make before commencing a
transmission, to ensure that transmitted speech is received clearly:
(a) First, listen out on the frequency you intend to use to make sure that there is no
interference from other transmitting stations. Whilst doing this the receiver volume
can be set to the optimum level.
(b) When speaking into the microphone maintain a constant distance between it and your
mouth. Transmitted speech can be seriously distorted if the microphone is held too
close to the mouth, if the lips are allowed to touch it whilst speaking. When using a
combined headset/microphone system, never hold either the microphone or its boom.
Number Transmitted as Pronounced as
0823 Two Three or Zero Eight Two Three TOO TREE (or ZERO AIT TOO TREE)
1300 One Three Zero Zero WUN TREE ZERO ZERO
2057 Five Seven or Two Zero Five Seven FIFE SEVEN (or TOO ZERO FIFE SEVEN)
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(c) Enunciate each word clearly and distinctly and use a normal conversational tone.
(d) Keep your rate of speech constant. About 100 words per minute should be the
maximum, but speak more slowly if you know that the recipient will be writing down
some or all of your transmission.
(e) Maintain the speaking volume at a constant level.
(f) A slight pause before and after numbers will assist in making them easier to
understand.
(g) Avoid using hesitation sounds such as er.
(h) Keep operation of the transmit button to a minimum. Depress the transmit switch
fully before speaking and do not release it until the message is complete. This will
ensure that the entire message is transmitted. However, do not depress transmit switch
until ready to speak.
(i) Remember that the first language of the recipient may not be the same as yours. The
use of standard radiotelephony (RT) phraseology, spoken clearly and distinctly, is
essential.
(j) Make sure that the transmit switch is released on completion of the transmission and
that it cannot be inadvertently switched on when the microphone is returned to its
stowage. A live out-of-use microphone is at best irritating to other operators and is
potentially dangerous, since it may obstruct an emergency transmission.
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Standard Words and Phrases
8. The following words and phrases are standard in radiotelephony communications as
appropriate and have the meaning given below:
Word/Phrase Meaning
ACKNOWLEDGE Let me know that you have received and understood this message.
AFFIRM Yes
APPROVED Permission for proposed action granted.
BREAK Indicates the separation between messages.
CANCEL Annul the previously transmitted message.
CHANGING TO I intend to call . . . (unit) on . . .(frequency)
CHECK Examine a system or procedure ( no answer is normally expected)
CLEARED Authorised to proceed under the conditions specified.
CLIMB Climb and maintain
CONFIRM Have I correctly received the following . . . ? or Did you correctly
receive this message?
CONTACT Establish radio contact with . . .(your details have been passed)
CORRECT This is correct
CORRECTION An error has been made in this transmission (or message indicated).
The correct version is . . .
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DESCEND Descend and maintain
DISREGARD Consider that transmission as not sent
FREECALL Call . . .(unit) (your details have not been passed - mainly used by
military ATC)
HOW DO YOU READ What is the readability of my transmission
I SAY AGAIN I repeat for clarity or emphasis
MONITOR Listen out on (frequency)
NEGATIVE No; or Permission not granted; or That is not correct
OVER* My transmission is ended and I expect a response from you
OUT* This exchange of transmissions is ended and no response is expected
PASS YOUR MESSAGE Proceed with your message
READ BACK Repeat all, or the specified part, of this message back to me exactly as
received
REPORT Pass requested information
REQUEST I should like to know . . . or I wish to obtain . . .
ROGER I have received all your last transmission
Under no circumstances to be used in reply to a question requiring a
direct answer in the affirmative (AFFIRM) or negative (NEGATIVE)
SAY AGAIN Repeat all, or the following part of your last transmission
SPEAK SLOWER Reduce your rate of speech
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* Not normally used in U/VHF communications
Departure Information and Engine Starting Procedures
9. Where no ATIS is provided the pilot may ask for current aerodrome information before
requesting start up. Note that in this and all subsequent examples the pilots transmission is shown
in italics in the left column and the ATC response in normal type in the right column.
STANDBY Wait and I will call you
No onward clearance to be assumed
VERIFY Check and confirm
WILCO I understand your message and will comply with it (abbreviation for
will comply)
WORDS TWICE As a request : Communication is difficult. Please send every word twice
As information: Since communication is difficult, every word in this
message will be sent twice
Cranmore Ground Centrair 4516, Request departure
Information
Centrair 4516 Cranmore Ground departure
runway 24 wind 225 3, QNH 1010,
Temperature +7 dewpoint -3, RVR 550
metres
Runway 24, QNH 1010, will Call for start up
Centrair 4516
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10. Requests to start engines are normally made to facilitate ATC planning and to avoid excessive
fuel wastage by aircraft delayed on the ground. At certain aerodromes, along with the request, the
pilot will state the location of the aircraft and acknowledge receipt of the departure ATIS broadcast
identifying letter together with the QNH.
11. When there will be a delay to the departure of the aircraft the controller will normally
indicate a time to start up or expect to start up.
Cranmore Ground Centrair 4516, Bay 7
information Bravo QNH 1010 request start up
Centrair 4516 Cranmore Ground start up at
time 04
Cranmore Ground Centrair 4516 Information
Charlie, QNH 1010, request start up
Centrair 4516 Cranmore Ground start up
approved, temperature +7
or
Centrair 4516 Cranmore Ground Expect
start up at time 04
or
Centrair 4516 Cranmore Ground Expect
departure at time 13 Start up when ready,
temperature +7
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Taxi Instructions
12. Taxi instructions issued by a controller will always contain a clearance limit, which is the
point at which the aircraft must stop unless further permission to proceed is given. For departing
aircraft the clearance limit will normally be the holding point of the runway in use, but may be any
other position on the aerodrome depending on the prevailing traffic.
Washford Tower G-PPSC C172 at Tango dispersal
Request taxi for VFR flight to Bridgwater
G-SC taxi to holding point runway 27 via
taxiway Alpha QNH 1018
Taxi to holding point Runway 27 via taxiway
Alpha QNH 1018 G-SC
G-SC request surface wind
G-SC surface wind 210 15
G-SC request runway 19
G-SC taxi to holding point Runway 19 via
taxiway Alpha, follow the Partenavia
immediately ahead of you.
Taxi to holding point Runway 19 via taxiway
Alpha. Following the Partenavia G-SC
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Washford Tower G-PPSC C172 at the compass
base VFR to Bridgwater request taxi
G-SC runway 19QNH 998
taxi to holding point runway 27 via
taxiway Bravo
QNH 998 G-SC request taxiway Bravo, and
backtrack runway 01
G-SC taxi holding point runway 01 via
taxiway Bravo
Taxi holding point runway 01 via taxiway Bravo
G-SC
Washford Tower G-PPSC at the compass base
request taxi to flying school
G-SC taxi to holding point runway 27 via
Bravo
Taxi holding point runway 27 via Bravo G-SC
G-SC holding point Runway 27 request cross
G-SC negative. I will call you
Holding G-SC
G-SC taxi to the flying school via Alpha,
cross runway 27 at the threshold report
vacated
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NOTE:
Report vacated may be omitted when aerodrome control has continuous sight
of the aircraft crossing.
13. Where an ATIS broadcast is established the controller does not need to pass departure
information to the pilot when giving taxi instructions. He will, however, check that the aircraft is in
possession of the latest QNH.
Taxi to the flying school via Alpha cross runway
27 at the threshold will report vacated G-SC
G-SC runway vacated
G-SC
Centrair 4516 Information Bravo, QNH 1005
request taxi
Centrair 4516, QNH 1004, after the Brymon
Dash 8 taxi to holding point runway 19
QNH 1004, after Dash 8 holding point
runway 19 Centrair 4516
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Aerodrome Traffic Circuit
FIGURE 2-1
Typical Left Hand
Circuit
Typical Left-hand Circuit
Position 1 Aircraft reports on downwind leg when abeam upwind end of runway.
Position 2 Base leg report (if required).
Position 3 Final report. Clearance to land issued here.
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Position 4 Long Final report (between 8 and 4 miles) when aircraft is on a straight in approach.
NOTE:
For light aircraft operations, circuit dimensions may be reduced but the
relative RT reporting points are maintained.
14. Requests for circuit-joining instructions should be made in sufficient time for a planned entry
into the circuit taking other traffic into account. Where ATIS is established, receipt of the broadcast
should be acknowledged in the initial call to an aerodrome. When the traffic circuit is a right-hand
pattern it shall be specified. A left-hand pattern need not be specified although it is essential to do so
when the circuit direction is variable.
15. In some circumstances, an aircraft may be instructed to complete a standard overhead joint
which comprises the following:
(i) Overfly at 2000ft above Aerodrome Elevation.
Crowcombe Tower G-PPSC C172 12 miles north
east altitude 2000 feet regional QNH 1018
Request joining instructions
G-SC join right-hand downwind runway 24
height 1000 feet QFE 1002
Join right-hand downwind runway 24 height
1000 feet QFE 1002 G-SC
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(ii) If not already known, determine the circuit direction from the signals square,
other traffic or windsock.
(iii) Descend on the dead side to circuit height (G-CD deadside descending).
(iv) Join the circuit by crossing the upwind end of the runway at circuit height.
(v) Position downwind.
NOTE:
Aerodromes with overhead joins at variance to the above standard procedure
will notify such differences.
16. Depending on prevailing traffic conditions and the direction from which an aircraft is
arriving, it may be possible to make a straight-in approach.
17. The pilot having jointed the traffic circuit makes routine reports as required by local
procedures.
Crowcombe Tower G-PPSC C172 12 miles north
east altitude 2000 feet regional QNH 1018 request
straight-in approach runway 24
G-SC cleared straight-in approach
runway 24 surface wind 300 degrees 10
knots QFE 1009 report final
Cleared straight-in approach Runway 24 QFE 1009.
Wilco G-SC
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18. It may be necessary, in order to co-ordinate traffic in the circuit, to issue delaying or
expediting instructions.
19. In order to save taxying time when flying training in the traffic circuit pilots may wish to
carry out a touch and go, i.e. the aircraft lands, continues rolling and takes-off, without stopping.
G-SC downwind G-SC Number 2 follow the Robin on base
Number 2, contact with the Robin G-SC
G-SC base G-SC
G-SC final G-CD cleared to land Runway 24 surface wind
295 9
Cleared to land runway 24 G-SC
G-SC extend downwind Number 2 to a Robin 4 miles
final
Extend downwind, Number 2 G-SC
G-SC delaying action. Orbit right report again on base
Orbit right, Wilco G-SC
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20. It is helpful for circuit management purposes if a controller is informed when an aircraft
which has been engaged in multiple approaches is on his last circuit.
Final Approach And Landing
21. A final report is made when an aircraft turns onto final approach. If the turn on is made at
a distance greater than 4nm from touchdown a long final report is made. The landing/touch and
go/low approach clearance will include the runway designation.
G-SC downwind touch and go G-SC Roger
G-SC final G-SC cleared touch and go Runway 24
surface wind calm
Cleared touch and go Runway 24 G-SC
or
G-SC unable to approve due traffic make full
stop landing cleared to land runway 24
surface wind calm
Cleared to land runway 24 G-SC
G-SC downwind last landing G-SC Roger
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NOTE:
Where an outer marker is installed, an outer marker instead of a final report
may be made.
22. Should the runway be obstructed when the aircraft makes its final report at 4nm or less
from touchdown, but is expected to be clear in good time for the aircraft to make a safe landing, the
controller will delay landing clearance.
G-SC final G-SC cleared to land Runway 24 surface wind
295 9
Cleared to land runway 24 G-SC
Centrair 4516 long final Centrair 4516 report final Surface wind 305 15
Wilco Centrair 4516
Centrair 4516 final Centrair 4516 cleared to land Runway 32
surface wind 315 18
Cleared to land runway 32 Centrair 4516
G-SC final G-SC Continue approach Surface wind 290 12
Continue approach G-SC
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23. The controller may or may not explain why the landing clearance has been delayed but the
instruction to continue IS NOT an invitation to land and the pilot must wait for landing clearance
or initiate a missed approach.
24. An aircraft may have landed, but not yet be clear of the runway. A following aircraft may be
permitted to touch down on the same runway provided that:
(i) The runway is long enough to allow safe separation between the two aircraft
and there is no evidence to indicate that braking may be adversely affected.
(ii) It is during daylight hours.
(iii) the controller is satisfied that the landing aircraft will be able to see the
preceding aircraft which has landed, clearly and continuously, until it is clear
of the runway; and
(iv) The pilot of the following aircraft is warned. (Responsibility for ensuring
adequate separation rests with the pilot of the following aircraft).
25. A pilot may request to fly past the control tower or other observation point for the purpose of
visual inspection from the ground
Centrair 4516, land after the Dash 8, runway 32,
surface wind calm
Land after the Dash 8 Centrair 4516
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26. If the low pass is made for the purpose of observing the undercarriage, on of the following
replies could be used to describe its condition but these examples are not exhaustive:
(i) Landing gear appears down.
(ii) Right (or left, or nose) wheel appears up (or down).
(iii) Wheels appear up.
(iv) Right (or left, or nose) wheel does not appear up (or down).
27. For training purposes, a pilot may request permission to make an approach along, or parallel
to the runway, without landing.
Centrair 4516 request low pass unsafe nose
gear indication
Centrair 4516 cleared low pass runway 32 surface
wind 295 12 not below 500 feet QFE 1012 report
final
Cleared low pass runway 32 not below 500
feet QFE 1012 Wilco Centrair 4516
Centrair 4516 request low approach for training Centrair 4516 cleared low approach
runway 32 surface wind 295 12 not below
300 feet above threshold elevation report
final
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28. FISOs will use different phraseology to indicate that there is nothing to prevent an aircraft
from landing.
29. Alternatively, if the runway is obstructed, or there are other aircraft ahead on final, FISOs will
use
Cleared low approach runway 32 not below 300
feet above threshold elevation Wilco Centrair 4516
Saltford Information G-PPSC final runway 19 G-PPSC Saltford Information land at your
discretion surface wind 150 4
G-PPSC
G-PPSC final runway 19 G-PPSC Saltford Information the runway is obstructed
with an F28
or
G-PPSC Saltford Information, one aircraft ahead on final
G-PPSC
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Essential Aerodrome Information
30. Essential aerodrome information is information regarding the manoeuvring area and its
associated facilities which is necessary to ensure the safe operation of aircraft. Aerodrome
information is passed to aircraft whenever possible prior to start-up or taxi and prior to the
commencement of final approach.
Centrair 4516 caution Construction work at the end of
stand 37
caution work in progress ahead north side of
taxiway Alpha
caution centreline taxiway lighting unserviceable
caution PAPIs runway 27 unserviceable
caution large flock of birds north of runway 27 near
centre taxiway
message from aerodrome authority, fire and rescue
services reduced. The aerodrome can only accept
aircraft up to and including category (number)
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Go Around
31. In order to avoid an unsafe situation, the controller may issue instructions to the pilot to
initiate a missed approach. Because cockpit workload is high during the missed approach procedure,
transmissions to the aircraft are kept brief and succinct..
32. In the event of a missed approach unless instructions are issued to the contrary, an aircraft on
an instrument approach procedure and an aircraft operating VFR is to continue into the normal
traffic circuit.
33. In the event of missed approach being initiated by the pilot the phrase going around shall be
used.
34. At military aerodromes GO AROUND is also employed to instruct an aircraft to fly another
circuit. Unless otherwise instructed, circuit height should be maintained (or regained) and a
Deadside call made before turning Crosswind to report Downwind.
Centrair 4516 go around I say again go around
acknowledge
Going around Centrair 4516
G-SC going around G-SC Roger
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After Landing
35. Unless absolutely necessary, controllers will not give taxi instructions to pilots until the
landing roll is complete. Unless otherwise advised pilots should remain on tower frequency until the
runway is vacated.
VFR Departures
36. Departing VFR flights, when handled by approach control may be passed information on
relevant known traffic in order to assist the pilot in maintaining his own separation. Pilots should
report leaving the area of jurisdiction of the approach control units.
Centrair 4516 vacate left
Vacate left Centrair 4516
Centrair 4516 take next right when
vacated contact ground 118.35
Next right when vacated ground 118.35 Centrair 4516
Harnham Approach G-SC G-SC Flight Information available from Greeston
124.55
Greeston Information 124.55 G-SC
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37. Special VFR flights will be given specific instructions in the clearance to leave the control
zone.
VFR Arrivals
38. Depending on the procedures in use, the pilot of an arriving VFR flight may be required to
establish contact with the approach control unit and request instructions before entering its area of
jurisdiction e.g. before entering a control zone. Where there is an ATIS broadcast the pilot should
acknowledge that he h as received it; where no ATIS broadcast is provided the approach controller
will pass the aerodrome data.
G-SC cleared to the zone boundary route
via November Special VFR not above
altitude 1500 feet
Cleared to the zone boundary, route via November
Special VFR not above altitude 1500 feet G-SC
G-SC correct
Longbarrow Approach G-PPSC G-PPSC Longbarrow Approach pass your message
G-PPSC C172 inbound from
Washford VFR 2000 feet regional
QNH 1018 estimating zone boundary
08 Kennington 18 information Golf
G-SC cleared from the zone boundary to Longbarrow
VFR, at 2000 feet Kennington QNH 1016.
Traffic information there is a southbound Warrior
2500 feet VFR estimating zone boundary 09
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Special VFR Flights
39. Special VFR clearances are only issued for flights within Control Zones and are normally at
the request of the pilot. The pilot:
(i) Must comply with ATC instructions.
(ii) Is responsible for ensuring that his flight conditions enable him to remain clear
of cloud, determine his flight path with reference to the surface and to keep
clear of obstructions.
(iii) Is responsible for ensuring that he flies within the limitations of his licence.
Cleared from the zone Boundary to
Longbarrow VFR at 2000 feet QNH
1016, traffic in sight G-SC
G-SC report aerodrome in sight
Wilco G-SC
G-SC aerodrome in sight G-SC contact Tower 118.5
Tower 118.5 G-SC
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(iv) Is responsible for complying with the relevant low flying restrictions of Rule 5
of the Rules of the Air Regulations. Note: Whilst the 1500ft rule may not
apply to a pilot in receipt of Special VFR clearance, the alight clear rule
always applies. The responsibility to determine whether to accept a Special
VFR clearance and still comply with this rule rests with the pilot.
(v) Is responsible for avoiding aerodrome traffic zones unless prior permission for
penetration has been obtained from the relevant ATSU.
40. A full flight plan is not required for Special VFR flight but the pilot must give brief details of
the call-sign, aircraft type and pilots intentions, including ETA at entry point. A full flight plan is
required if the pilot wishes his destination to be notified.
41. Aircraft are not normally given a specific height to fly but vertical separation from aircraft
flying above can be achieved by requiring the Special VFR flight to fly not above a specified level
(Section (v) above must be borne in mind by pilots).
42. No separation will be provided between Special VFR flights which are flying in notified areas
or routes where an individual clearance is not required, or between flights using such areas or routes
and other flights on Special VFR clearances. Full details of the procedures for Special VFR flights
appear in the UK AIP.
Callsigns for Aeronautical Stations
43. Aeronautical stations are identified by:
(i) The name of the location, and
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(ii) The unit or service available.
44. The unit or service may be identified in accordance with the table below except that the name
of the location or the unit/service may be omitted provided satisfactory communication has been
established.
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45. There are three main categories of aeronautical communications service:
Air Traffic control service (ATC) which can only be provided by licensed Air Traffic Control
Officers who are closely regulated by the CAA.
Unit/Service Available Call Sign Suffix
Area Control Centre CONTROL
Approach Control APPROACH
Approach Control Radar Arrivals ARRIVAL
Approach Control Radar Departures DEPARTURE
Aerodrome Control TOWER
Surface Movement Control GROUND
Radar (in general) RADAR
Precision Approach Radar PRECISION
Direction-Finding Station HOMER
Flight Information Service INFORMATION
Clearance Delivery DELIVERY
Apron Control APRON
Company Dispatch DISPATCH
Aeronautical Station RADIO
General Operating Procedures
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Flight information service at aerodromes can be provided only by licensed Flight Information
Service Officers (FISOs) who are mainly self-regulating.
Aerodrome air/ground communications service (A/G) which can be provided by Radio Oper-
ators who are not licensed but have obtained a certificate of competency to operate radio
equipment on aviation frequencies from the CAA. These operations come under the jurisdic-
tion of the radio license holder, but are not regulated in any other way.
46. It is an offense to use a callsign for a purpose other than that for which it has been notified.
47. When satisfactory communication has been established, and provided that it will not be
confusing, the name of the location or the callsign suffix may be omitted.
Aircraft Callsigns
48. An aircraft radiotelephony call-sign shall be one of the following types:
Type a) The characters corresponding to the registration marking of the aircraft, or
Type b) the telephony designator of the aircraft operating agency, followed by the last four
characters of the registration marking of the aircraft.
Type c) The telephony designator of the aircraft operating agency, followed by the flight
identification.
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NOTE:
Note 1 The name of aircraft manufacturer or name of aircraft model may be
used as a radiotelephony prefix to the Type a) call-sign above.
NOTE:
Note 2 The call-signs referred to in (a), (b) and (c) above comprise
combinations in accordance with the ITU Radio Regulations (No.2129 and
No.2130).
NOTE:
Note 3 The telephony designators referred to in (b) and (c) above are contained
in IAO Document 8585 - Designators for Aircraft Operating Agencies,
Aeronautical Authorities and Services.
NOTE:
Note 4 Any of the foregoing call-signs may be inserted in Field 7 of the ICAO
flight plan as the aircraft identification. Instructions on the completion of the
flight plan from are contained in PANS-RAC, Document 4444.
49. When establishing communication an aircraft shall use the full callsigns of both stations.
General Operating Procedures
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50. After satisfactory communication has been established and provided that no confusion is
likely to occur, the ground station may abbreviate callsigns (see table below). A pilot may only
abbreviate the callsign of his aircraft if it has been abbreviated by the aeronautical ground station.
51. Abbreviated call-signs shall be in the following form:
Type a) The first character of the registration and at least the last two characters of the call-sign.
Type b) the telephony designator of the aircraft operating agency, followed by at least the last two
characters of the call-sign.
Type c) No abbreviated form.
NOTE:
Note: Either the name of the aircraft manufacturer or the aircraft model may
be used in place of the first character in Type (a) above.
Washford Tower G-PPSC G-PPSC Washford Tower
Full callsign Abbreviation
G-PPSC G-SC
Speedbird G-BOAC Speedbird AC
General Operating Procedures
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52. * The name of either the aircraft manufacturers or name of aircraft model may be used as a
prefix to the callsign.
53. An aircraft should request the service required on initial contact when freecalling a ground
station.
54. An aircraft shall not change its callsign type during a flight. However, where there is
likelihood that confusion may occur because of similar callsigns, an aircraft may be instructed by an
air traffic service unit (ATSU) to change the type of its callsign temporarily. When the likelihood of
confusion no longer exists an aircraft will be instructed to revert to flight plan callsign.
N31029 N029
N753DA N3DA
Midland 120 No abbreviation
*Piper G-BSZT Piper ZT
Storrington Approach, G-PPSC
Request Lower Airspace Radar Service
Oakford Control, G-PPSC I wish to
file an airborne flight plan
General Operating Procedures
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55. Aircraft in the heavy wake turbulence category shall include the word HEAVY immediately
after the aircraft callsign in the initial call to each ATSU.
Transfer of Communications
56. An aircraft will normally be advised by the appropriate aeronautical station to change from
one radio frequency to another in accordance with agreed procedures.
57. In the absence of such advice, the aircraft shall notify the aeronautical station before such a
change takes place. Aircraft flying in controlled airspace must obtain permission from the
controlling authority before changing frequency.
58. An aircraft may be instructed to standby on a frequency when it is intended that the ATSU
will initiate further communications, and to monitor a frequency on which information is being
broadcast.
Centrair 4516 contact Oakford Control 127.4
Oakford Control 127.4 Centrair 4516
Centrair 4516 standby for Longbarrow weather
Centrair 4516
Centrair 4516 monitor 117.5 for Tower
General Operating Procedures
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59. If the airspace does not indicate that an aircraft must remain in contact with a specific ATSU
and the pilot wishes to freecall another agency he should request, or notify such an intention.
Test Procedures
60. Test transmissions should take the following form:
(a) the identification of the aeronautical station being called;
(b) the aircraft identification;
(c) the words RADIO CHECK;
(d) the frequency being used.
61. Replies to test transmission should be as follows:
(a) the identification of the station calling;
(b) the identification of the station replying;
Monitor 117.5 for Tower Centrair 4516
Westbury G-PPSC request change to Oakford Information on 126.5
Wrayton Information G-PPSC changing to Oakford Centre on 121.5 for Practice Plan
General Operating Procedures
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(c) information regarding the readability of the transmission.
62. The readability of a transmission should be classified by the number in the table below,
together with any other information regarding the transmission that may be useful to the station
making the test.
Readability Scale Meaning
1 Unreadable
2 Readable now and then
3 Readable but with difficulty
4 Readable
5 Perfectly readable
Washford Tower G-PPSC radio check 118.7 G-PPSC Washford Tower readability 5
Or
G-SC Washford Tower readability 3 with a
loud background whistle
Or
Station calling Washford Tower readability 1
General Operating Procedures
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63. When it is necessary for a ground station to make test signals, either for the adjustment of a
transmitter before making a call or for the adjustment of a receiver, such signals shall not continue
for more than 10 seconds. The test should comprise spoken numbers (WUN, TOO, TREE etc)
followed by the radio callsign of the station transmitting the test signals.
Issue of Clearance and Readback Requirements
64. Provisions governing clearances are contained in the PANS-RAC (ICAO Doc 4444). A
clearance may vary in content from a detailed description of the route and levels to be flown to a
brief standard instrument departure (SID) according to local procedures.
65. Controllers will pass a clearance slowly and clearly since the pilot needs to write it down;
wasteful repetition will thus be avoided. Whenever possible a route clearance should be passed to an
aircraft before start up and the aircrafts full callsign will always be used. Generally controllers will
avoid passing a clearance to a pilot engaged in complicated taxiing manoeuvres and on no occasion
when the pilot is engaged in line up or take-off manoeuvres.
66. An ATC route clearance is not an instruction to take-off or enter an active runway. The
words take-off are used only when an aircraft is cleared for take-off. At all other times the word
departure is used.
67. The stringency of the read back requirement is directly related to the possible seriousness of a
misunderstanding in the transmission and receipt of ATC clearance and instructions. ATC route
clearances shall always be read back unless otherwise authorised by the appropriate ATS authority in
which case they shall be acknowledged in a positive manner. Read backs shall always include the
aircraft callsign.
General Operating Procedures
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.
Centrair 4516 cleared to Longbarrow via R3,
at FL 85 Request level change en-Route,
squawk 5501
Cleared to Longbarrow via R3, at FL 85,
request level change en-route, squawk 5501
Centrair 4516
Centrair 4516 correct
Fastair 4516 cleared to Longbarrow via R3,
Twyford 3 Delta departure, squawk 5501
Cleared to Longbarrow via R3, Twyford 3 Delta
departure, squawk 5501, Fastair 4516
Fastair 4516 correct
G-PPSC after departure cleared to zone
boundary via route Charlie. Climb altitude
2500 feet QNH 1018, squawk 6783
After departure cleared to zone boundary via
route Charlie. Climb altitude 2500 feet QNH
1018, squawk 6783 G-PPSC
G-SC correct
General Operating Procedures
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68. Pilots of departing aircraft flying in controlled airspace which suffer radio communication
failure prior to reaching cruising level should be aware of the procedures to be adopted when the
following types of clearance (detailed in UK AIP RAC 6) are issued:
(a) Request level change en-route.
(b) Climb under radar.
(c) Temporary restriction to climb.
69. The ATC messages listed below are to be read back in full by the pilot. If the controller does
not receive a readback the pilot will be asked to do so. Similarly, the pilot is expected to request that
instructions are repeated or clarified if any are not fully understood.
(i) Level Instructions
(ii) Heading Instructions
(iii) Speed Instructions
(iv) Airways or Route Clearances
(v) Runway-in-Use
(vi) Clearance to Enter, Land On, Take-Off On, Backtrack, Cross, or Hold Short of
an Active Runway
(vii) SSR Operating Instructions
General Operating Procedures
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(viii) Altimeter Settings
(ix) VDF Information
(x) Frequency Changes
(xi) Type of Radar Service
G-PPSC cleared to cross R3 at Twyford, maintain
FL 95 whilst in controlled airspace. Report
entering the airway
Cleared to cross R3 at Twyford, maintain FL
95 in controlled airspace, Wilco. G-PPSC
G-SC hold position
Holding G-SC
G-SC contact Ground 118.05
Ground on 118.05 G-SC
Centrair 4516 Squawk 5408
5408 Centrair 4516
General Operating Procedures
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70. Items which do not appear in the above list may be acknowledged with an abbreviated read
back.
71. If an aircraft read back of a clearance or instructions is incorrect, the controller shall transmit
the word NEGATIVE followed by the correct version.
72. If at any time a pilot receives a clearance or instruction with which he cannot comply, he
should advise the controller using the phrase UNABLE (COMPLY) and give the reason (s).
Centrair 4516 after the A340 passing left to
right, taxi to the holding point runway 27
After the A340, holding point 27, Centrair 4516
G-SC QNH 1003
QNH 1013 G-SC
G-SC Negative, QNH 1003
QNH 1003 G-SC
Centrair 4516 Corsham climb FL 280, cross
Twyford FL 150 or above
General Operating Procedures
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Corsham Centrair 4516 unable climb
FL 280 due weight
General Operating Procedures
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Self Assessed Exercise No. 2
QUESTIONS:
QUESTION 1.
Write the phonetic pronunciation of the frequency 145.9
QUESTION 2.
Write the following registration identifier in phonetic pronunciation style: ZV-LHD.
QUESTION 3.
In words, how would the following heights be transmitted: a. 2500ft b. 1350ft c. 1500ft d.
25000ft
QUESTION 4.
In words, how would the following frequency be transmitted: 132.375
QUESTION 5.
In words, how would the following time be transmitted: 0642
QUESTION 6.
What should be the maximum number of words per minute spoken on RT?
QUESTION 7.
What is the purpose of standard words and phrases?
General Operating Procedures
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QUESTION 8.
What is the difference between roger and affirm?
QUESTION 9.
What is the difference between contact and freecall?
QUESTION 10.
What word is used for let me know that you have received and understood this message?
QUESTION 11.
When may a pilot abbreviate his/her callsign?
QUESTION 12.
When, and at what range, is the call long final made?
QUESTION 13.
When is a full flight plan required for a special VFR flight?
QUESTION 14.
In controlled airspace, before changing frequency, what must a pilot do?
QUESTION 15.
On the readability scale, what are 3 and 5 respectively?
General Operating Procedures
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QUESTION 16.
When may a pilot use the phrase take-off?
QUESTION 17.
List the ATC messages for which readback is mandatory.
QUESTION 18.
If you are asked to climb to a new level, and for some reason you cannot, what phrase is used to
inform ATC?
ANSWERS:
ANSWER 1.
Wun fower fife dayseemal niner
ANSWER 2.
Zulu Victor Lima Hotel Delta
ANSWER 3.
two thousand five hundred feet
one thousand three hundred and fifty feet
one thousand five hundred feet
two five thousand feet
General Operating Procedures
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ANSWER 4.
One three two decimal three seven
ANSWER 5.
Four two OR zero six four two
ANSWER 6.
About 100.
ANSWER 7.
To eliminate ambiguity because of different languages
ANSWER 8.
Roger I have received your last transmission
Affirm yes
ANSWER 9.
Contact establish contact with XXXX. Details have been passed.
Freecal call XXXX. Details have not been passed.
ANSWER 10.
Acknowledge
General Operating Procedures
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ANSWER 11.
Only if it has been first abbreviated by the ground station
ANSWER 12.
When doing a straight-in approach at between 4 and 8 miles.
ANSWER 13.
If the pilot requires the destination to be notified.
ANSWER 14.
Request permission to change.
ANSWER 15.
3 readable with difficulty
5 perfectly readable
ANSWER 16.
Only when cleared for take-off.
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ANSWER 17.
Level instructions
Heading instructions
Speed instructions
Airways or route clearances
Runway in use
Clearance to enter, land on, take-off on, backtrack, cross, or hold short of an active runway
SSR operating instructions
Altimeter settings
VDF information
Frequency changes
Type of radar service
ANSWER 18.
unable (comply) and give reasons.
091 VFR Communications
G LONGHURST 1999 All Rights Reserved Worldwide
Radar Procedural Phraseology
Radar Identification and Vectoring
Secondary Surveillance Radar
Radar Service
Radar Vectoring
Traffic Information and Traffic Avoidance
ACAS/TCAS
Radar Assistance to Aircraft with Radio Communication
Failure
UK Danger Area Crossing Service/Danger Area Activity
Information Service
Radar Procedural Phraseology
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3Radar Procedural Phraseology
1. The following paragraphs contain general radar phraseology that is commonly used in
communications between aircraft and all types of radar unit.
2. The phrase under radar control shall only be used when a radar control service is being
provided. Normally however, the callsign suffix used by the radar unit is sufficient to indicate its
function.
3. In a radar environment heading information given by the pilot and heading instructions given
by controllers are normally in degrees magnetic.
Radar Identification and Vectoring
4. An aircraft must be identified before it can be provided with a radar service. However, the act
of identifying aircraft is not a service in itself and pilots should not assume that they are receiving a
radar service, particularly when they are flying outside controlled airspace.
G-SC report heading
G-SC heading 120
G-SC for identification turn Left heading 090
Left heading 090 G-SC
Radar Procedural Phraseology
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5. When a controller has identified an aircraft he will inform the pilot, according to the
circumstances, of the following:
(a) that the aircraft is identified, and
(b) the position of the aircraft.
6. The occasions when the above information will be passed can be summarised as follows:
G-SC identified 24 miles west of Kennford, Radar Advisory
Radar Advisory G-SC
or
G-SC not identified. Resume own navigation.
Wilco G-SC
Method of Identification Aircraft flying inside controlled
airspace
Aircraft flying outside controlled
airspace
Inform Identified Pass Position Inform Identified Pass Position
SSR No No Yes Yes
Turn Yes Yes Yes Yes
Departing aircraft No No Yes No
Position Report No No Yes No
Radar Procedural Phraseology
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7. The pilot will be warned if identification is lost, or about to be lost, and appropriate
instructions given.
Secondary Surveillance Radar
8. The following phrases are instructions that may be given by controllers to pilots regarding the
operation of SSR transponders. The phrases used by controllers are given together with their
meanings; assignment of a code does not constitute the provision of a radar service.
G-SC radar service terminated due radar failure. Resume
own navigation. Flight Information available from
Oakford on 125.75
Changing to Oakford 125.75 G-SC
G-SC will shortly be leaving radar cover, radar service
terminated. Flight Information available from Oakford on
125.75
G-SC Changing to Oakford 125.75 G-CD
Radar Procedural Phraseology
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9. *Used to verify the accuracy of the Mode C derived level information displayed to the
controller.
10. The pilot must respond to SSR instructions, reading back specific settings.
Phrase Meaning
Squawk (code) Set the mode and code as instructed
Confirm squawk Confirm the mode and code set on the transponder
Recycle (mode) (code) Reselect assignment mode and code
Squawk Ident Operate the special position identification feature
Squawk Mayday Select Emergency
Squawk standby Select the standby feature
Squawk Charlie Select altitude reporting feature
Check altimeter setting and report your level Check pressure setting and report your level
Stop squawk Charlie Deselect altitude reporting
Stop squawk Charlie, Wrong indication Stop altitude report, incorrect level readout
*Verify your level Check and confirm your level
Centrair 4516 squawk 6411
6411 Centrair 4516
Radar Procedural Phraseology
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Radar Service
11. Where it is not self-evident pilots will normally be informed by the controller when they are
under radar control, advisory or information service.
Centrair 4516 squawk ident
Squawk ident, Centrair 4516
Centrair 4516 squawk 6411 and ident
6411 and ident, Centrair 4516
Centrair 4516 confirm squawk
Alpha 6411 Centrair 4516
Centrair 4516 recycle 6411
Recycling 6411 Centrair 4516
Centrair 4516 check altimeter setting
1018 set Centrair 4516
Centrair 4516 confirm transponder Operating
Centrair 4516 negative, transponder
unserviceable
Radar Procedural Phraseology
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Radar Vectoring
12. Aircraft may be given specific vectors to fly in order to establish separation. Pilots may be
informed of the reasons for radar vectoring.
13. It may be necessary for a controller to know the heading of am aircraft a separation can often
be established by instructing an aircraft to continue on its existing heading.
Centrair 4516 under Radar Control
Radar Control Centrair 4516
G-SC Radar Advisory
Radar Advisory G-SC
G-SC Radar Information
Radar Information G-SC
Centrair 4516 radar service terminated
Centrair 4516
Centrair 4516 delaying action. Turn left heading 090
Left heading 090 Centrair 4516
Radar Procedural Phraseology
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14. A controller may not know the aircrafts heading but does require the aircraft to fly a
particular heading.
Centrair 4516 continue present heading
Continue heading Centrair 4516
Centrair 4516 report heading
Centrair 4516 heading 090
Centrair 4516 continue present heading and report
that heading
Continue heading 050 Centrair 4516
Centrair 4516 continue heading 050
Continue heading 050 Centrair 4516
G-SC fly heading 045
Roger, turning left heading 045, G-SC
or
Roger, turning left 20 degrees heading 045, G-SC
Radar Procedural Phraseology
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15. When vectoring is complete, pilots will be instructed to resume their own navigation, given
position information and appropriate instructions as necessary.
16. Occasionally an aircraft may be instructed to make a complete turn (known as an orbit or a
360-degree turn), for delaying purposes or to achieve a required spacing behind preceding traffic.
Centrair 4516 resume own navigation for Twyford,
magnetic track 350 distance 18 miles
Wilco Centrair 4516
G-SC resume own navigation for Blackdown position
is 19 miles north of Shaftesbury
Wilco G-SC
G-SC delaying action, orbit left for sequencing
Orbit left G-SC
Centrair 4516 delaying action. Make a 360-degree
turn left
360 turn left Centrair 4516
Radar Procedural Phraseology
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Traffic Information and Traffic Avoidance
17. Whenever practicable, information regarding traffic on a possible conflicting path should be
given in the following form:
(a) relative bearing of the conflicting traffic in terms of the 12 hour clock; or, if the
aircraft under service is established in a turn, the relative position of the conflicting
traffic in relation to cardinal points i.e.: north-west, south etc;
(b) distance from the conflicting traffic;
(c) direction of flight of the conflicting traffic; and
(d) relative speed of the conflicting traffic or type of aircraft and level if this is known.
18. Relative movement should be described by using one of the following terms as applicable:
(i) closing, converging, parallel, same direction, opposite direction diverging,
overtaking, crossing left to right, crossing right to left.
(ii) 'closing crossing right to left; (if level is known) - 1000ft above or below.
19. The controller will inform the pilot when the conflict no longer exists.
G-SC unknown traffic 4 oclock crossing right to left
height unknown fast moving. If not sighted turn left
heading 090
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20. Avoiding action to be taken by the pilot is given when the controller considers that an
imminent risk of collision will exist if action is not taken immediately.
ACAS/TCAS
21. ACAS/TCAS equipment reacts to transponders of other aircraft in the vicinity to determine
whether or not there is a potential confliction. The warning (Traffic Advisory (TA)), based on the
time to an assumed collision enables the pilot to identify the conflicting traffic, and if necessary, take
avoiding action (Resolution Advisory (RA)). In the UK, this equipment is mainly referred to as
TCAS; however, the use of ACAS is an acceptable alternative in phraseology terms.
22. Pilots should report TCAS manoeuvres.
Left heading 090 G-SC
G-SC clear of traffic resume own navigation direct
Blackdown magnetic track 350 distance 27 miles
Wilco G-SC
G-SC avoiding action, turn left immediately
heading 090 traffic at 4 oclock 5 miles crossing
right to left slightly above fast moving
Left heading 090 G-SC
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23. The pilot should report a TCAS manoeuvre even if it was not possible to notify the Controller
that an RA had occurred
.
24. Pilots should report that they are unable to comply with a clearance as a result of a TCAS
alert.
25. In these circumstances the pilot should report when clear of the TCAS conflict
Centrair 4516 TCAS climb/descent Centrair 4516 Roger
Centrair 4516 TCAS clear of conflict,
returning to (assigned clearance)
Centrair 4516 Roger
(Controllers may issue a revised clearance at this point.)
Centrair 4516 TCAS climb/descent, clear of
conflict, (assigned clearance) resumed
Centrair 4516 Roger
(Controllers may issue a revised clearance at
this point.)
Centrair 4516 unable comply, TCAS RA Centrair 4516 Roger
Radar Procedural Phraseology
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Radar Assistance to Aircraft with Radio
Communication Failure
26. When a controller suspects that an aircraft is able to receive but not transmit messages, the
radar may be used to confirm that the pilot has received instructions. When further instructions are
given they should be passed slowly, clearly and be repeated.
NOTE:
An aircraft experiencing a radio communications failure is expected to select
the appropriate SSR code.
G-SC reply not received if you read Oakford turn left heading 260
I say again turn left heading 260
G-SC turn observed I will continue
to pass instructions
or
Centrair 4516 reply not received If you read Oakford squawk ident
I say again squawk ident
Centrair 4516 squawk observed I will
continue to pass instructions
Radar Procedural Phraseology
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UK Danger Area Crossing Service/Danger Area
Activity Information Service
27. In-flight information on the status of Danger Areas (DAs) is available from the nominated
service units:
(a) Listed in the UK AIP.
(b) Detailed on the legend of the appropriate UK 1:500 000 Aeronautical Chart.
28. When available the DA service will either be a Danger Area Crossing Service (DACS) or a
Danger Area Activity Information Service (DAAIS). If there is no reply from the appropriate
nominated service unit which is to be called for these services, pilots are advised to assume that the
relevant danger area is active.
Danger Area Crossing Service
29. The appropriate nominated service unit will, whenever the DA activity permits, provide a
clearance for an aircraft to cross the danger area under a RIS or FIS. The clearance is only in relation
to Danger Area activity and does not, in traffic management terms, constitute separation from
aircraft that might be operating in the area.
Carhampton Approach, G-PPSC Request Danger
Area Crossing Service Of Aberfeldy Range
G-PPSC Carhampton Approach Flight
Information Service. Aberfeldy active.
Report 10 miles from Aberfeldy
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Wilco G-PPSC
Carhampton Approach G-PPSC 10 miles from
Aberfeldy
G-SC Aberfeldy remains active. Suggest
you re-route
Re-routing to the south of Aberfeldy and changing
to Oakford Information 125.75 G-SC
G-SC
or
G-PPSC Carhampton Approach. Aberfeldy
not active, range crossing approved report
vacating the range
Range crossing approved. Wilco G-PPSC
G-PPSC vacating Aberfeldy Range G-SC Carhampton Approach Roger, Flight
Information available from Oakford on
125.75
Changing to Oakford on 125.75 G-SC
Radar Procedural Phraseology
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Danger Area Activity Information Service
30. The nominated service unit will pass to the pilot, on request, an update on the known activity
status of the danger area. Such an update will assist the pilot to decide whether it would be prudent,
on flight safety grounds, to penetrate the Danger Area. A DAAIS does NOT constitute a clearance to
cross a Danger Area.
31. Full details of DACS/DAAIS can be found in the UK AIP and AICs.
Carhampton Approach G-PPSC request
DAAIS for Aberfeldy Range
G-PPSC Carhampton Approach Aberfeldy
Active/Not Active
Aberfeldy Active/Not Active G-PPSC
091 VFR Communications
G LONGHURST 1999 All Rights Reserved Worldwide
Relevant Weather Information Terms
Meteorological Information
METAR
Voice Weather Broadcast (VOLMET) UK
Automatic Terminal Information Service (ATIS) UK
Relevant Weather Information Terms
Chapter 4 Page 1 G LONGHURST 1999 All Rights Reserved Worldwide
4Relevant Weather Information Terms
Meteorological Information
1. Meteorological information in the form of reports, forecasts or warnings is made available to
pilots using the aeronautical mobile service either by broadcast (e.g. VOLMET) or by means of
specific transmissions from ground personnel to pilots. Such information may be provided by:
(i) VOLMET (VHF). METARS and TRENDS.
(ii) VOLMET (HF).METARS and TRENDS and TAFS
(iii) ATIS. Aerodrome weather.
(iv) SIGMET. Significant or hazardous weather.
2. Standard meteorological abbreviations and terms should be used and the information should
be transmitted slowly and enunciated clearly in order that the recipient may record such data as
necessary.
G-SC Highbridge Tower 1530 Weather surface wind
265 degrees 15 knots visibility 15 km, Nil weather, 4
oktas 20,000 feet temperature plus 10, dew point
plus 3, QNH 10002
Relevant Weather Information Terms
Chapter 4 Page 2 G LONGHURST 1999 All Rights Reserved Worldwide
NOTE:
Cloud may also be reported as follows:
3. Scattered at five hundred feet, scattered cumulonimbus at one thousand feet, broken at two
thousand five hundred feet.
4. In the above example scattered equates to 3 or 4 Octas and broken equates to 5 7 Octas.
METAR
5. The METAR is a routine meteorological aerodrome report and contains information
concerning actual conditions at the time of the observation.
6. The basic format of the METAR message is as follows:
QNH 1002 G-SC
REPORT TYPE METAR, a routine weather report, or SPECI, a special report which is issued
between routine reports when conditions change significantly. Special reports
are discussed shortly.
LOCATION Given as an ICAO four-letter station identifier.
Relevant Weather Information Terms
Chapter 4 Page 3 G LONGHURST 1999 All Rights Reserved Worldwide
DATE/TIME Where it is necessary to include this group after the station identifier (normally
when the report is completed more than ten minutes removed from the normal
observation time) a six-figure date/time group is given, followed by the letter Z
to denote UTC. The first two figures give the day of the month and the last
four figures the time. eg: 241530Z
SURFACE
WIND
The wind direction is expressed as three digits and represents the true wind
direction rounded to the nearest whole 10.
The wind speed is expressed as two (exceptionally three) digits and is followed
by an abbreviation which represents the units of measurement of wind speed
(KT for knots, KMH for kilometres per hour and MPS for metres per second.
For example 32025KT represents a wind of 320(T) blowing at 25 knots.
The wind which is given is the mean wind over the ten minutes preceding the
time of the observation.
An additional two (exceptionally three) figures are added when the maximum
wind speed during the ten minutes preceding the time of the report exceeds the
mean wind speed by 10kt or more. The mean wind speed digits and the
maximum wind speed digits are separated by the letter G, for example
18025G40KT, signifying a mean wind speed of 25 knots, gusting 40 knots.
Relevant Weather Information Terms
Chapter 4 Page 4 G LONGHURST 1999 All Rights Reserved Worldwide
A calm condition is indicated by 00000 followed by the abbreviation for the
wind speed units. With a wind of 3kt or less which is variable in direction the
wind direction digits are replaced by the letters VRB followed by the wind
speed and the abbreviation for the wind speed units. When the wind speed is
4kt or more, VRB will only be used when the variation in direction exceeds
180.
If, during the ten minutes preceding the time of the observation, the total
variation in wind direction is 60 or more, the two observed extreme
directions between which the wind has varied are given in clockwise order, but
only when the wind speed is greater than 3kt. The two extremes of wind
direction are separated by the letter V. For example 32020G35KT 290V350
decodes as a wind which is varying in direction from 290(T) to 350(T) with
a mean direction of 320(T) and which has a mean speed of 20kt but a
maximum speed (over a ten minute period) of 35kt.
VISIBILITY When there is no marked variation in visibility by direction the surface
horizontal visibility is given by four digits which represent the visibility
expressed in metres. 9999 represents a visibility of 10km or more and 0000 a
visibility of less than 50 metres.
When there is a marked directional variation in the visibility the reported
minimum is followed by one of the eight points of the compass to indicate the
direction, for example 3000SW decodes as a visibility of 3000 metres in a
south-westerly direction (the visibility being better in other directions).
Relevant Weather Information Terms
Chapter 4 Page 5 G LONGHURST 1999 All Rights Reserved Worldwide
When the minimum visibility is less than 1500 metres and the visibility in
another direction greater than 5000 metres, the value and direction of the
maximum visibility will also be given, for example 1300SE 7000N.
RVR (if
applicable)
An RVR group always includes the prefix R followed by the runway
designator and the diagonal followed by the touchdown zone RVR in metres.
If the RVR is assessed on two or more runways simultaneously the RVR group
is repeated for each runway. Parallel runways are distinguished by appending
the letters L, C or R (left, centre or right) to the runway designator. For
example R23L/1100 R23R/1200.
When the RVR is greater than the maximum value which can be assessed the
group will be preceded by the letter P followed by the highest value which can
be assessed. When the RVR is assessed as more than 1500 metres it is
reported as P1500. When the RVR is below the minimum value that can be
assessed it is shown as a letter M followed by that minimum value, for
example R04/M0050 means that the RVR in the touchdown zone of runway
04 is measured as less than the minimum assessable value of 50 metres.
It if possible to determine the mean values of RVR, the mean values over the
ten minute period immediate preceding the observation are reported. Trends
and significant variations are reported as follows:
Relevant Weather Information Terms
Chapter 4 Page 6 G LONGHURST 1999 All Rights Reserved Worldwide
Trends. If the RVR values during the ten minute period preceding the
observation show a distinct increasing or decreasing tendency, such that the
mean value during the first five minutes differs from the mean value during the
second five minutes by 100 metres or more, this trend is reported. This is
done by following the RVR value by the letter U (increasing) or D
(decreasing). The letter N is used to indicate no significant change during the
ten minute period. For example R30/1000D means that the mean touchdown
zone value of RVR on runway 30 within the ten minutes preceding the time of
observation is 1000 metres and that it has decreased by 100 metres or more
during that ten minutes.
Significant Variations. When the RVR varies significantly such that, during
the ten minute period preceding the observation, the one minute mean extreme
values vary from the ten minute mean value by either more than fifty metres or
more than 20% of the ten minute mean value (whichever is the greater), the
one minute mean minimum and maximum values will be given in that order
separated by the letter V. This group will replace the ten minute mean value,
for example R09/0800V1100.
You might be relieved to learn that UK aerodromes will not be using RVR
trend or significant variation reports for the time being, however you may
encounter them on overseas METARs (or in the examination).
Relevant Weather Information Terms
Chapter 4 Page 7 G LONGHURST 1999 All Rights Reserved Worldwide
WEATHER Each weather group may consist of the appropriate intensity indicators (+ or -
) and letter abbreviations combined in groups of two to nine characters. If
they appear (as two figures) the intensity indicators are taken from the full
synoptic code. The abbreviations that are used in the weather groups are
shown in the table at Figure 1.
When neither a -(light) or a +(heavy) appears where you might expect an
intensity indicator, the phenomena should be assumed to be moderate.
Mixtures of precipitation types are reported in combinations as one group
with the dominant type given first, possible prefixed by +(heavy), -(light), SH
or TS as appropriate.
Up to three separate groups may be given to indicate the presence of more
than one independent weather type.
Each weather group is encoded by working from top to bottom of the table at
Figure 1, that is to say that the intensity or proximity comes first, followed by
description and then the weather phenomena, for example MIFG (shallow
fog), VCBLSN (blowing snow adjacent to but not at the aerodrome), +SHRA
(heavy showers or rain) or RASN (predominately rain but also snow.
If necessary to clarify the difference between BCFG and PRFG. BCFG is taken
to mean fog patches randomly covering the aerodrome. PRFG indicates that a
substantial part of the aerodrome is covered by fog while the remainder is
clear, in other words fog banks.
Relevant Weather Information Terms
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Note that the abbreviations BR, HZ, FU, IC, DU and SA are not reported
when the visibility is greater than 5000 metres.
Abbreviation Meaning
Intensity or Proximity
-
+
VC
Light
Heavy, or well developed when preceding PO or FC
In the vicinity (within 8km of the aerodrome perimeter)
Descriptor
MI
BC
PR
DR
BL
SH
TS
FZ
Shallow
Patches
Partial conv
Drifting
Blowing
Shower(s)
Thunderstorm
Super Cooled
Precipitation
Relevant Weather Information Terms
Chapter 4 Page 9 G LONGHURST 1999 All Rights Reserved Worldwide
DZ
RA
SN
SG
IC
PE
GR
GS
Drizzle
Rain
Snow
Snow Grains
Diamond Dust
Ice Pellets
Hail
Small Hail (less than 5mm diameter) and/or snow pellets
Obscuration
BR
FG
FU
VA
DU
SA
HZ
Mist
Fog
Smoke
Volcanic Ash
Widespread Dust
Sand
Haze
Other
PO
SQ
FC
SS
DS
Well developed dust/sand whirls
Squalls
Funnel cloud(s) (tornado or water-spout)
Sand Storm
Dust Storm
Relevant Weather Information Terms
Chapter 4 Page 10 G LONGHURST 1999 All Rights Reserved Worldwide
CLOUD Cloud (other than significant convective cloud) is reported in six character
groups. In each group the first three characters are letters as follows:
FEW (few) to indicate one or two oktas.
SCT (scattered) to indicate three or four oktas.
BKN (broken) to indicate five to seven oktas.
OVC (overcast) to indicate eight oktas.
The last three characters are figures which indicate the height of the cloud
above aerodrome level in hundreds of feet.
Significant convective clouds are considered to be CB (cumulonimbus) and
TCU (towering cumulus). When this type of cloud is observed the letters
CB or TCU as appropriate are added to the six character group, for
example SCTO18CB which indicates three or four oktas cumulonimbus
with a base height of 1800ft above aerodrome level.
The reporting of layers or masses of cloud is made as follows:
The first group gives the lowest individual layer of any amount.
The second group gives the next individual layer of more than two oktas.
The third group gives the next higher layer of more than four oktas.
Any additional groups give details of any significant convective cloud
(regardless of amount) if not already reported in the first three groups.
The cloud groups are given in ascending order of base height, for example
SCT005 SCT010 SCT018CB.
Relevant Weather Information Terms
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When there is no cloud to report and CAVOK does not apply (discussed
shortly), the cloud group is replaced by the letters SKC (sky clear).
Sky obscured is encoded as VV followed by the vertical visibility in
hundreds of feet. When the vertical visibility cannot be assessed the group
will read VV///. VV003 therefore decodes as sky obscured, vertical visibilty
300 feet.
Vertical visibility is not presently reported in UK METARS.
CAVOK The visibility, RVR, weather and cloud groups are replaced by CAVOK
when the following conditions are observed:
The visibility is 10km or more.
There is no cloud below 5000ft or below the Minimum Sector Altitude,
whichever is the greater, and there is no cumulonimbus.
There is no precipitation, thunderstorms, shallow fog or low drifting snow.
AIR
TEMPERATURE
AND DEWPOINT
This group normally consists of two figures followed by an oblique
followed by two figures, giving first the surface air temperature and then
the dew-point, both in degrees celsius. When the temperature and the dew-
point are below zero the figures are preceded by the letter M. Examples of
the temperature/dew-point group follow:
03/01 = temperature +30C, dew-point +10C
M01/M03 = temperature -10C, dew-point -30C
Relevant Weather Information Terms
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SUPPLEMENTARY INFORMATION
QNH This is reported as a four figure group, preceded by the letter Q, giving the
QNH rounded down to the nearest whole millibar. If the QNH is less than
1000mb the first figure in the group will be a 0, for example Q0994,
In the USA, QNH is given in inches of mercury. This will again be a four
figure group, representing hundredths of inches, prefixed by the letter A.
Therefore A2919 is a QNH of 29.19 inches.
RECENT
WEATHER
Operationally significant weather which has been observed at the station
since the last routine report or in the last hour (whichever period is
shorter) but not at the time of the report (or if the phenomena is present
at the time of the report, but has decreased in intensity), is included in the
METAR and is preceded by the letters RE, for example RETS.
Operationally significant weather is considered to be moderate or heavy
rain (RERA), moderate or heavy drizzle (REDZ), moderate or heavy rain
and drizzle (RERA), snow (RESN), blowing snow (REBLSN), ice pellets
(REPE), hail (REGR), small hail and/or snow pellets (REGS),
thunderstorms (RETS), dust or sand storms (RESS or REDS), volcanic
ash (REVA) and funnel cloud (REFC).
Relevant Weather Information Terms
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WIND SHEAR Windshear may be inserted if it is reported along the approach or take-
off paths in the lowest 1600ft with reference to the runway. Windshear
reports are preceded by the letters WS, for example WS TKOF RWY09,
WS LDG RWY09.
Windshear is not presently reported in UK METARs.
RUNWAY STATE An additional eight-figure runway state group may be added to the end
of a METAR when the runway is contaminated (by snow, standing water
and so on).
The format of the eight-figure runway state group is as follows:
First two digits Runway designator.
Third digit The type of contamination (wet snow,
water patches and so on).
Fourth digit Extent of runway contamination.
Fifth and sixth digits Depth of deposit.
Seventh and eight digits Friction co-efficient or braking action.
It is not intended to include the decode of the eight-figure group in this
manual, it would be unwise to try and remember the full decode,
mistakes could be painful. As an operating pilot however, you would be
well advised to keep a copy of the decode in your flight folder. The full
decode is to be found n the UK AIP, MET Section, Pages 3-5 to 3-7.
Relevant Weather Information Terms
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AUTO and RMK Where a report contains fully automated observations with no human
intervention, it will be indicated by the word AUTO inserted
immediately before the wind group.
The indicator RMK (remarks) denotes an optional section containing
additional meteorological elements.
RMK is not used with UK METARs.
MISSING
INFORMATION
Information that is missing in a METAR or SPECI may be replaced by
diagonals.
TRENDS For selected aerodromes, a forecast of significant changes in conditions
during the two hours following the time of observation may be given.
The letters BECMG (becoming) or TEMPO (temporarily) may appear
and may then be followed by FM (from) followed by a four-figure time
group and possibly TL (until) followed by a further four-figure time
group. Alternatively the letters AT (at) followed by a four-figure time
group may be used. Standard weather codes are then used to describe
the expected changes. The letters NOSIG (no significant change) may be
used to replace the trend groups. Examples of trends are given below:
BECMG FM1100 25034G59kt
TEMPO FM0630 TL0830 3000 SHRA
Relevant Weather Information Terms
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A trend will be appended to a METAR, providing that a forecaster is on
duty (as opposed to an observer), whenever one or more of the following
significant changes are expected to occur:
Wind velocity:
Changes in direction of 30 degrees or more, if the mean speed exceeds
20kt.
Changes in the mean speed of 10kt or more.
Changes in the gust speed of 10kt or more if the mean speed is 15kt or
more.
Visibility:
Changes through 150m, 350m, 600m, 1500m, 3000m and 5000m.
Weather:
(i) Onset, cessation, or change in intensity of
thunderstorms, freezing precipitation, moderate or
heavy drizzle or rain.
(ii) Onset or cessation of low drifting or blowing sand,
dust or snow, squall, funnel cloud, sand or dust
storm.
Relevant Weather Information Terms
Chapter 4 Page 16 G LONGHURST 1999 All Rights Reserved Worldwide
Special Reports
7. Additional METARs will be issued if the conditions change significantly since the last
observation. The conditions which would give rise to a SPECI (special) METAR are given below.
Note that within the UK a SPECI METAR is not normally transmitted beyond the station of origin.
Cloud:
(i) Change in cloud ceiling through or to 100, 200,
300, 500, 1000 or 1500ft (cloud ceiling is defined
as the lowest level of cloud which obscures more
than 4 oktas of the sky).
(ii) Change through or to 4 oktas for clouds having a
base at or below 1500ft.
Wind Velocity:
Change in direction of 30 degrees or more, if speed exceeds 20kt, or a change
of 60 degrees or more if the mean speed is 10kt or more.
Changes in the mean speed of 10kt or more.
The difference between mean and maximum speed increases by 10kt or more,
with a mean speed of 15kt or above.
Relevant Weather Information Terms
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Visibility:
Changes through 800, 1500, 5000 or 10,000 metres, also, when RVR values
are not available, changes through 150, 350 and 600 metres.
8. RVR:
9. Changes through 150m, 350m, 600m and 800m.
Weather:
The onset or cessation of moderate or heavy rain, rain and snow, snow, ice
pellets, snow pellets or hail.
The onset or cessation of freezing fog or freezing precipitation.
The onset or cessation of thunderstorms, squalls, funnel cloud, sand or dust
storms and low drifting or blowing snow, sand or dust.
A change in intensity of any of the precipitation forms listed above from slight
to moderate or heavy or from moderate or heavy to slight.
Cloudbase:
Changes of cloud ceiling through 100, 200, 300, 500, 700, 1000, 1500 or
2000ft.
Changes through or to 4 oktas for clouds having a base at or below 1500ft.
QNH:
Changes of pressure of 1mb or more.
Relevant Weather Information Terms
Chapter 4 Page 18 G LONGHURST 1999 All Rights Reserved Worldwide
10. The notes above on the METAR code may have served only to thoroughly confuse the reader.
If so, an attempt at decoding the METARs given below will hopefully serve to prove how easy it
really is. Remember that the information is always given in the order in which it was discussed
above.
METAR 1
11. METAR EGLL 091220Z 14005KT 045E R12/1000N DZ BCFG W//// 09/07 Q1004 NOSIG
=
Decode
CAVOK:
A METAR which contained a CAVOK report will be replaced by a Special
(SPECI) report if the visibility falls to below 10km or the cloud base falls to
below 2000ft, or if CB is present.
EGLL London Heathrow
091220Z At 1220 UTC on the 9th day of the month
14005KT Mean surface wind (over a ten minute period) 140(T)/05kt
0450E Visibility 450 metres to the east of the aerodrome
Relevant Weather Information Terms
Chapter 4 Page 19 G LONGHURST 1999 All Rights Reserved Worldwide
METAR 2
METAR LFPB 091220Z 24015KT 200V280 8000 -RA SCT010
BKN025 OVC080 18/15 Q0983 TEMPO 3000 RA BKN008
OVC020 =
Decode
R12/1000 RVR at the touchdown zone of the runway 12 is 1000 metres with no
significant change over a ten minute period
DZ Moderate drizzle
BCFG Patches of fog randomly covering the aerodrome
W//// Sky obscured, vertical visibility cannot be assessed
09/07 Air temperature +90C, dew-point +70C
Q1004 QNH 1004mb
NOSIG No significant changes are forecast for the next two hours
LFPB Paris Le Bourget
091220Z At 1220 UTC on the 9th day of the month
Relevant Weather Information Terms
Chapter 4 Page 20 G LONGHURST 1999 All Rights Reserved Worldwide
24015KT Mean surface wind 240(T)/15kt
200V280 Extremes of wind direction over a ten minute period from 200(T) to 280(T)
8000 Visibility 8000 metres
-RA Light rain
SCT010 Lowest cloud base height 1000ft above aerodrome level (three or four oktas)
BKN025 Five to seven oktas of cloud base height 2500ft above aerodrome level
OVC080 Eight oktas of cloud base height 8000ft above aerodrome level
18/15 Air temperature +18C, dew-point +15C
Q0983 QNH 983mb
TEMPO Temporarily within the next two hours
3000 Visibility 3000 metres
RA Moderate rain
BKN008 Five to seven oktas of cloud base height 800ft above aerodrome level
OVC020 Eight oktas of cloud base height 2000ft above aerodrome level
Relevant Weather Information Terms
Chapter 4 Page 21 G LONGHURST 1999 All Rights Reserved Worldwide
METAR 3
METAR EGAA 091220Z 30025G38KT 270V360 1200NE 6000S
+SHSNRAGS SCT005 BKN010CB 03/M01 Q0999 RETS WS LDG
RWY27 BECMGAT1300 9999 SCT015 BKN100 =
Decode
EGAA Belfast Aldergrove
091220Z At 1220 UTC on the 9th day of the month
30025G37KT Mean surface wind direction 300(T), mean surface wind speed (over ten
minutes 25 kt, maximum wind speed (over ten minutes) 37 kt
270V360 Extremes of wind direction over a ten minute period from 2700(T) to 3600(T)
1200NE Minimum visibility 1200 metres to the northeast
6000S Maximum visibility 6000 metres to the south
+SHSNRAGS Heavy showers of snow, rain and small hail
SCT005 Lowest cloud base height 500ft above aerodrome level (three or four oktas)
BKN010CB Five to seven oktas cumulonimbus, base height 1000ft above aerodrome level
03/M01 Air temperature +3Air temperature, dew-point -10C,
Relevant Weather Information Terms
Chapter 4 Page 22 G LONGHURST 1999 All Rights Reserved Worldwide
12. Volmet broadcasts are essentially METARs transmitted in plain language. Similarly ATIS
broadcasts (Automatic Terminal Information Service) contain plain language METARs (but now
with the wind direction in degrees magnetic), together with details of runway in use, initial contact
frequency, work in progress, and so on.
Voice Weather Broadcast (VOLMET) UK
13. VOLMET broadcasts are aerodrome meteorological reports for certain aerodromes. They
take two forms, continuous and scheduled broadcasts. Details of the callsign, frequency, operating
hours and aerodromes for which the service is provided are contained in the UK AIP.
Q0999 QNH 999mb
RETS Thunderstorms since the last report or in the last hour (whichever period is the
shorter) but not at this time
WS LDG R
RWY27
Windshear has been reported below 1600ft on the approach to Runway 27
BECMGAT13
00
Becoming at 1300 UTC
9999 Visibility 10km or more
SCT015 Three or four oktas, base 1500ft aal
BKN100 Five to seven oktas, base 10,000ft aal
Relevant Weather Information Terms
Chapter 4 Page 23 G LONGHURST 1999 All Rights Reserved Worldwide
14. Continuous VOLMET broadcasts are normally transmitted in the VHF band and they
contain current meteorological reports for aerodromes, with trends where available.
15. Schedule VOLMET broadcasts are normally transmitted in the HF band and, in addition to
aerodrome weather reports andtrends where available, may also contain forecasts.
16. The content of a VOLMET broadcast is as follows:
(a) Aerodrome identification (e.g. Bratton)
(b) Surface wind
(c) Visibility (Note 1)
(d) RVR (if applicable) (Note 1)
(e) Weather
(f) Cloud (Note 1)
(g) Temperature
(h) Dewpoint
(i) QNH
(j) Trend (if applicable).
Relevant Weather Information Terms
Chapter 4 Page 24 G LONGHURST 1999 All Rights Reserved Worldwide
NOTE:
Non essential words such as surface wind, visibility etc are not spoken.
SNOCLO is used to indicate that aerodrome is unusable for take-off/landings
due to heavy snow on runways or snow clearance. All broadcasts are in
English.
Automatic Terminal Information Service (ATIS) UK
17. At busy aerodromes the amount of voice radio transmissions necessary for control of aircraft
in the air and on the ground is high. In order to avoid overloading controllers an Automatic
Terminal Information Service (ATIS) continuously broadcasts routine arrival and departure
information on a discrete RTF frequency or in conjunction with an appropriate VOR.
18. Pilots of inbound aircraft are normally required, when first contacting the aerodrome Air
Traffic Service Unit (ATSU), to acknowledge receipt of current information by quoting the
appropriate code letter of the ATIS broadcast.
19. Pilots of outbound aircraft are normally only required to acknowledge receipt of departure
information unless the ATIS broadcast requests them to do so. In such cases the QNH given in the
broadcast should be repeated, so that ATC can check that the ATIS quoted QNH is current.
20. The duration of the ATIS broadcast should not exceed thirty seconds and will include the
following:
(a) Message identification i.e.: This is Bratton Information Alpha. Each message is
consecutively coded using the phonetic alphabet.
Relevant Weather Information Terms
Chapter 4 Page 25 G LONGHURST 1999 All Rights Reserved Worldwide
(b) Time of origin of weather report.
(c) Weather report.
(d) Runway (s) in use.
(e) Short term AIS information such as unserviceability of NAV AIDS, runway surfaces
etc.
(f) Any other routine information useful to pilots operating at the aerodrome.
NOTE:
RVR/RVRs are not included, however, IRVRs may be available where
approved.
NOTE:
Rapidly changing meteorological situations sometimes make it impractical to
include weather reports in the broadcast. In these circumstances, ATIS
messages will indicate that weather information will be passed on RTF. Any
significant change to the content of a current ATIS message will be passed to
pilots by RTF until such time as a new message is broadcast. The highest cloud
base that will be reported is 10000 feet.
Example of ATIS broadcast:
Relevant Weather Information Terms
Chapter 4 Page 26 G LONGHURST 1999 All Rights Reserved Worldwide
This is Bratton Approach Information Alpha. 1230 hours weather. 180 8 kts. 15 km.
Intermittent drizzle. 4 octas 1000 ft, 8 octas 1800 ft. Temperature +5. Dew point +7 QNH 997
mbs. Landing runway 19. Report information Alpha received on first contact with Bratton.
NOTE:
A Trend may be included in an ATIS broadcast.
091 VFR Communications
G LONGHURST 1999 All Rights Reserved Worldwide
Action Required to be Taken in Case of
Communication Failure
Air to Ground
Ground to Air
Action Required to be Taken in Case of Communication Failure
Chapter 5 Page 1 G LONGHURST 1999 All Rights Reserved Worldwide
5Action Required to be Taken in Case
of Communication Failure
Air to Ground
1. When an aircraft fails to establish contact with the aeronautical station on the designated
frequency, the pilot should attempt to establish contact on another frequency, appropriate to the
route being flown. If this fails, the aircraft station should then attempt to establish communication
with other aircraft or other aeronautical stations, on frequencies appropriate to the route being
flown. In addition, an aircraft operating within a network should monitor the appropriate VHF
frequency for calls from nearby aircraft.
(a) When communication failure occurs or is suspected, the following points should be
checked:
(i) the correct frequency has been selected for the route being flown.
(ii) the Aeronautical Station being called is open for watch.
(iii) the aircraft is not out of radio range.
(iv) receiver volume correctly set.
Action Required to be Taken in Case of Communication Failure
Chapter 5 Page 2 G LONGHURST 1999 All Rights Reserved Worldwide
(b) If these points are in order, it may be that the aircraft equipment is not functioning
correctly. Complete the checks of headset and radio installation appropriate to the
aircraft.
(c) If the pilot is still unable to establish communication on any designated aeronautical
station frequency, or with any other aircraft, he should then transmit his message
twice, on the designated frequency, preceded by the phrase TRANSMITTING
BLIND. This is in case the transmitter is still functioning.
(d) Where a transmitter failure is suspected, check or change the microphone. Listen out
on the designated frequency for instructions. It should be possible to answer
questions by use of the carrier wave if the microphone is not functioning (see
Speechless Code, Chapter 6, paragraph 6.5).
(e) In the case of a receiver failure transmit reports twice at the scheduled times or
positions on the designated frequency preceded by the phrase TRANSMITTING
BLIND DUE TO RECEIVER FAILURE.
(f) An aircraft which is being provided with air traffic control, advisory service or
aerodrome flight information is to transmit information regarding the intention of the
pilot in command with respect to the continuation of the flight. Specific procedures
for the action to be taken by pilots of IFR and Special VFR flights are contained in the
appropriate AIP sections.
(g) When an aircraft is unable to establish communication due to airborne equipment
failure it shall, when so equipped, select the appropriate SSR code to indicate radio
failure (A7600).
Action Required to be Taken in Case of Communication Failure
Chapter 5 Page 3 G LONGHURST 1999 All Rights Reserved Worldwide
(h) When the aircraft forms part of the aerodrome traffic at a controlled aerodrome, the
pilot should keep a watch for such instructions as may be issued by visual signals.
Ground to Air
2. After completing checks of ground equipment (most airports have standby and emergency
communications equipment) the ground station will request other aeronautical stations and aircraft
to attempt to communicate with the aircraft that has failed to maintain contact.
3. If still unable to establish communication the aeronautical station will transmit messages
addressed to the aircraft by blind transmission on the frequency on which the aircraft is believed to
be listening.
These will consist of:
(a) The level, route and expected approach time (EAT), or estimated time of arrival
(ETA), to which it is assumed the aircraft is adhering.
(b) The weather conditions at the destination aerodrome and suitable alternate. Also, if
practicable, the weather conditions in an area or areas suitable for a procedural
descent through cloud to be effected. (See AIP Section).
In Visual Meteorological Conditions, the Aircraft Shall:
(a) continue to fly in visual meteorological conditions;
(b) land at the nearest suitable aerodrome; and
Action Required to be Taken in Case of Communication Failure
Chapter 5 Page 4 G LONGHURST 1999 All Rights Reserved Worldwide
(c) report its arrival by the most expeditious means to the appropriate air traffic control
unit.
091 VFR Communications
G LONGHURST 1999 All Rights Reserved Worldwide
Distress and Urgency Procedures
States of Emergency
VHF Emergency Service
Use of the Service General Procedures
Emergency Message
Speechless Code
Practice Emergencies Radio Procedures
Training Fix
Relayed Emergency Message
Imposition of Silence
Cancellation of Emergency Communication and
RTF Silence
Distress and Urgency Procedures
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6Distress and Urgency Procedures
1. During an emergency in UK airspace there are specific RTF procedures that should be used
under the Aeronautical Mobile Service. The characteristics of these procedures and of the VHF
International Aeronautical Emergency Service are described in this Chapter.
States of Emergency
There are two recognised states of emergency, classified as follows:
(a) Distress A condition of being threatened by serious and/or imminent danger and of
requiring immediate assistance.
(b) Urgency A condition concerning the safety of an aircraft or other vehicle, or of some
person on board or within sight, but not requiring immediate assistance.
Distress Signals
2. When a condition of grave and/or imminent danger threatens, requiring immediate assistance,
distress signals are made using one or more of the following methods:
(a) the group SOS (...---...) in Morse Code is sent repeatedly by radiotelegraphy or by any
other signalling method available (e.g. hand lamp or flashing the aircraft landing
lights);
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(b) a voice message is transmitted by radiotelephony, consisting of the word MAYDAY
repeated at least three times and followed, if practicable, with a brief description of
the emergency and the aircraft location;
(c) rockets or shells throwing red lights, fired one at a time at short intervals;
(d) a parachute flare showing a red light.
NOTE:
Article 41 of the ITU Radio Regulations (Nos. 3268, 3270 and 3271 refer)
provides information on the alarm signals for actuating radiotelegraph and
radiotelephone auto-alarm systems:
3268 The radiotelegraph alarm signal consists of a series of twelve dashes sent in one
minute; the duration of each dash being four seconds and the duration of the interval
between consecutive dashes one second. It may be transmitted by hand but its
transmission of an automatic instrument is recommended.
3270 The radiotelephone alarm signal consists of two substantially sinusoidal audio
frequency tones transmitted alternatively. One tone shall have a frequency of 2200
Hz and the other a frequency of 1300 Hz, the duration of each tone being 250
milliseconds.
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Urgency Signals
3. When a pilot is experiencing difficulties that compel him to land the aircraft, but which do
not require immediate assistance, the following signals are used, either together or separately:
(a) switching the landing lights on and off repeatedly;
or
(b) switching the navigation lights on and off repeatedly, but in such a manner as to be
distinct from automatic flashing navigation lights.
4. When a pilot has a very urgent message to transmit concerning the safety of another vehicle
(ship, aircraft, etc.) or of a person either onboard his aircraft or within sight, the following signals are
used:
(a) a signal made by radiotelegraphy or by any other signalling method consisting of the
group XXX;
(b) a signal sent by radiotelephony consisting of the spoken words PAN, PAN, PAN.
3271 The radiotelephone alarm signal, when generated by automatic means, shall be sent
continuously for a period of at least thirty seconds but not exceeding one minute;
when generated by other means, the signal shall be sent as continuously as
practicable over a period of approximately one minute.
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VHF Emergency Service
The UK Distress and Diversion Service
5. Within the United Kingdom there are two Distress and Diversion (D&D) Sections located at
Area Control Centres (ACC), one at West Drayton near London and the other at Kinloss in Scotland.
They are manned by RAF control staff, who are assisted by suitably equipped civil and military units
and certain HM Coastguard stations. They provide a VHF emergency service on the International
Aeronautical Emergency frequency of 121.5 MHz.
6. The service provided is available continuously to all pilots flying within UK airspace. It
provides assistance where pilots are in distress, in urgent need of assistance or experiencing
difficulties that could develop into an emergency, such as uncertainty of location.
7. Provided that there is no actual emergency in progress on the UHF or VHF frequencies the
service may also be available for practice emergencies. the UK AIP (COM Section) contains further
information on the emergency service for civil pilots.
8. The principal function of the two D & D Sections is to provide an emergency aid and position
fixing service for civil and military pilots. Over most of the London FIR and to the south and east of
Manchester autotriangulation (Direction Finding) is available on 121.5 MHz. For other civil aircraft
incidents where the VHF frequency is used the Sections rely on DF bearings passed by telephone
from VDF equipped stations. it should be appreciated that this position-fixing procedure is relatively
slow. This is because the bearing information received must be manually plotted onto 1:250,000
charts, which normally requires several minutes concentrated activity.
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9. The accuracy of the position fix depends to a large extent upon the altitude of the aircraft
requesting the service and its distance from the VDF stations used to obtain bearings. Below 3000 ft
amsl the VHF fixing service coverage is limited and in areas where there is intervening high ground,
such as Scotland, Wales and SW England, VDF location of low flying aircraft may be severely
inhibited.
10. Where direction finding data on 121.5 MHz is unavailable the D & D controller is limited to
that information available from secondary surveillance radar (SSR) and what the pilot in distress can
provide concerning his route, last known position and observed topography.
11. An effective emergency communications aid service is also available at certain UK
aerodromes, listed in the UK AIP. Some of these aerodromes maintain a continuous VHF listening
watch on 121,5 MHz, although they may not necessarily be equipped with VDF or SSR.
12. Others which do have VDF, but do not maintain a listening watch on the VHF emergency
frequency, may be asked by the D & D controller to provide bearing information and other
assistance. In such a case, the controller may instruct the pilot the switch temporarily to the
frequency of the station where VDF is available.
Use of the Service General Procedures
13. The London D & D Section covers UK airspace south of latitude N55 and the Scottish
Section covers the airspace north of N55. Emergency calls on 121.5 MHz should be addressed
accordingly, unless the pilot is in doubt regarding his position in relation to latitude N55.
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14. Once two-way communication with the D & D Controller has been established the pilot
should not change frequency from 121.5 MHz without first telling the controller. It should be noted
that the provision of emergency services by the D & D Sections of the ACCs is unique to the UK.
Information on Search and Rescue (SAR) services is detailed in the UK AIP.
15. It is very much in pilots own interest to contact the emergency services as soon as there is any
doubt concerning the safe conduct of their flight. When so doing, it is vital to pass details of the
difficulty being experienced and the nature of the service required as clearly and fully as possible.
For example, a vague request for confirmation of position is unlikely to be accorded the same
priority as a clear statement that he is lost.
16. If a pilot is already in communication with a civil or military ATSU, before the emergency
arises, assistance should be requested from the controller on the frequency is use. In this case, any
SSR code setting previously assigned by ATC (other than the Conspicuity Code 7000) should be
retained until instructions are received to change the code setting.
17. If however, the pilot is not in direct communication with an ATSU and the aircraft is equipped
with an SSR transponder it should be switched, preferably before the emergency call is made, to
Mode A Emergency Code 7700, with Mode C if available. If the transponding aircraft is high
enough to be within secondary radar cover, the selection of the Emergency 7700 Code will alert the
Emergency Controller to the presence of an incident by means of an audio and visual warning. The
received SSR plot will show the precise location of the aircraft on the controllers radar display, and
will then obviate the need for the emergency controller to carry out the more time-consuming manual
aircraft position plotting procedure. Information on SSR operating procedures, including Special
Purpose Codes 7700 (Emergency), 7600 (Radio Failure) and 7500 (Hijack or Other Act of Violence )
are detailed in the AIP.
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Emergency Message
18. The emergency message shall contain the following information (time and circumstance
permitting) and, whenever, should be possible, should be passed in the order given.
(a) MAYDAY/MAYDAY/MAYDAY (or PAN PAN/PAN PAN/PAN PAN);
(b) Name of the station addressed (when appropriate and time and circumstances
permitting);
(c) Callsign;
(d) Type of aircraft;
(e) Nature of the emergency
(f) Intention of the person-in-command;
(g) Present or last known position, flight level/altitude and heading;
(h) Pilot qualifications (See Note 1), viz:
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(i) Any other useful information e.g. endurance remaining, number of people of board
(POB) etc.
NOTE:
There are no ICAO requirements to include pilot qualifications in a distress
message. However, this information should be included whenever possible in
UK emergency messages as it may help the controller to plan a course of action
best suited to a pilots ability.
(i) Student pilots (see Note 2);
(ii) No Instrument Qualification;
(iii) IMC Rating
(iv) Full Instrument Rating.
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NOTE:
Inexperienced civil pilots are invited to use the callsign prefix TYRO when in
communication with a military unit or the D&D Section to indicate their lack
of experience. Upon hearing this code word, military controllers will ensure
that they do not issue complex instructions that the pilot could have difficulty
in following.
MAYDAY MAYDAY MAYDAY
Woodcombe Tower G-PPSC Cherokee
engine failure losing height intend an
immediate forced landing 15 mileseast of
Woodcombe. passing4500 feet heading
260 PPL no instrument qualification 2
POB
G-PPSC Woodcombe Tower roger
MAYDAY(any pertinent information)
MAYDAY MAYDAY MAYDAY
Woodcombe Tower G-PPSC Cherokee
engine failed. will attempt to land
Woodcombe,10 miles east, 4500 ft heading
270 PPL no instrument qualification 2
POB
G-PPSC Woodcombe Tower roger MAYDAY
cleared straight-in runway 24 wind 260 10 knots
QFE 1018 you are number one
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Action by the station addressed or first station acknowledging the distress message.
19. The station addressed by aircraft in distress, or first station acknowledging the distress
message, shall:
(a) Immediately acknowledge the distress message.
(b) Take control of the communications or specifically and clearly transfer that
responsibility, advising the aircraft if a transfer is made.
(c) Take immediate action to ensure that all necessary information is made available, as
soon as possible, to:
(d) The ATS unit concerned.
(e) The aircraft operating agency concerned, or its representative, in accordance with pre-
established arrangements.
(f) Warn other stations, as appropriate, in order to prevent the transfer of traffic to the
frequency of the distress communication.
NOTE:
The requirement to inform the aircraft operating agency concerned does not
have priority over any other action which involves the safety of the flight in
distress, or of any other flight in the area, or which might affect the progress of
expected flights in the area.
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Speechless Code
20. If an emergency message received by the Military Emergency Controller is weak or distorted
to the point of being unintelligible, the pilot may be asked to adopt the Speechless Code. This entails
the pilot pressing his transmit button a certain number of times and using carrier wave only
transmissions which, by convention, have the following code meanings:
Number of Transmissions Meaning
One Short Yes or an acknowledgement
Two Short No
Three Short Say again (to be used by the pilot when he has not fully heard
the controllers transmission , or he has not understood the
transmission , or was an instruction and the pilot is unable to
comply)
Four Short (letter H in morse) Request Homing (to an airfield), or used for initial alerting.
(A civil pilot should only use the four short transmissions if he
is aware, or suspects before attempting to make initial contact
with the Emergency Controller, that his own aircraft
microphone is unserviceable. The Emergency Controller will
then interrogate the pilot, using the callsign Speechless
Aircraft if the identity of the aircraft is unknown)
One long (2 secs) Manoeuvre Complete (eg steady on heading)
One Long, Two Short and One
Long (-..-) (letter X in morse)
My aircraft has developed another emergency
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21. An aircraft SSR transponder can also be used, during times of communication difficulties, by
a pilot to acknowledge or respond to messages by the transmission of SSR Code changes or
squawking Ident as requested by the controller.
22. If neither the state if DISTRESS nor URGENCY applies, a service is available at lower
priority to pilots who find themselves in DIFFICULTY. Such pilots should make their situation cleat
and then provide as much information as possible to the emergency controller from the list
previously described.
Practice Emergencies Radio Procedures
23. Pilots may simulate emergency incidents (BUT NOT THE STATE OF DISTRESS) on 121.50
MHz to enable them to gain experience of the ATC service provided. Before calling, pilots should
listen out on the emergency frequency to ensure that no actual or practice incident is already in
progress. Practice calls need not disrupt a planned flight or involve additional expense in fuel or time
since the pilot can request diversion to his intended destination or cancel the exercise when
necessary. Simulated emergency calls must be prefixed PRACTICE and should be brief, e.g.:
24. PRACTICE PAN, PRACTICE PAN, PRACTICE PAN London Centre G-PPSC
25. The Emergency Controller will then indicate acceptance of the Practice Pan by transmitting:
26. G-PPSC, London Centre continue with PRACTICE PAN
27. The Emergency Controller may instruct the pilot to call at another time, if the practice cannot
be accommodated.
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28. If a practice is accepted, the pilot should then pass his details. SSR Mode A Code 7700
should not be selected during a practice emergency exercise unless required by the Emergency
Controller. Mode C should be switched on, if available.
Training Fix
29. Pilots who do not wish to carry out a practice emergency but only wish to confirm their
position may request a Training Fix on 121.5 MHz. This Training Fix is secondary in importance
to actual emergency calls, but takes precedence over practice emergency calls in the event of
simultaneous incidents.
(Listen out before transmitting)
Relayed Emergency Message
30. Any aeronautical station or aircraft knowing of an emergency incident may transmit a
distress message whenever such action is necessary to obtain assistance for the aircraft or vessel in
distress. In such circumstances, it should be made clear that the aircraft transmitting is not itself in
distress.
Training Fix, Training Fix, Training Fix, G-PPSC
G-PPSC, London Centre your position is 15
miles west of Dorchester
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Imposition of Silence
31. Transmissions from aircraft in distress have priority over all other transmissions. On hearing
a distress call, all stations must maintain radio silence on that frequency unless they themselves are
required to render assistance and should continue to listen on the frequency concerned until it is
evident that assistance is being provided. Stations should take care not to interfere with the
transmission of urgency calls.
32. The aircraft in distress or the station in control of a distress incident may impose silence either
on all stations in the area or on any particular station that interferes with distress transmissions. In
either case, the message should take the following form:
33. The aeronautical station acknowledging a distress message on a particular frequency may
consider it prudent to transfer other aircraft from that frequency in order to avoid any disruption or
transmission from or to the emergency aircraft.
MAYDAY MAYDAY MAYDAY Woodcombe Tower G-
PPSC has intercepted MAYDAY from G-OOPS I say
again G-OOPS Piper Cub engine failure forced landing
5 miles south of Detling VOR, 2000 feet descending,
heading 355, IMC rating, over
G-PPSC Woodcombe Tower Roger
your relayed MAYDAY from G-
OOPS
All stations Milthorpe Tower Stop transmitting MAYDAY
or
G-PPSC stop transmitting MAYDAY
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Cancellation of Emergency Communication and
RTF Silence
34. When an aircraft is no longer in distress it shall transmit a message cancelling the emergency
condition.
35. When a distress incident has been resolved, the station that has been controlling the
emergency traffic will transmit a message indicating that normal working may be resumed.
MAYDAY G-OOPS. All other aircraft contact
Woodcombe Tower on 123.8, out
Woodcombe Tower G-OOPS cancel MAYDAY,
engine restarted, runway in sight. request landing
G-PS cleared to land Runway 24. Surface
wind 260 8
Cleared to land runway 24 G-PS
All stations Woodcombe Tower MAYDAY
traffic ended
091 VFR Communications
G LONGHURST 1999 All Rights Reserved Worldwide
General Principles of VHF Propagation
and Allocation of Frequencies
General Allotment of Frequency Band 117.975 137 MHz
Frequency Separation and Limits of Assignable
Frequencies
Frequencies Used for Particular Functions
Utilisation in the Band 108-117.975 MHz
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7General Principles of VHF
Propagation and Allocation of
Frequencies
The radio frequency spectrum is divided into the following bands:
Band Frequency Range
VLF Very Low Frequency 3 - 30 KHz
LF Low Frequency 30 - 300 KHz
MF Medium Frequency 300 KHz - 3 MHz
HF High Frequency 3 - 30 MHz
VHF Very High Frequency 30 - 300 MHz
UHF Ultra High Frequency 300 MHz - 3 GHz
SHF Super High Frequency 3 - 30 GHz
EHF Extremely High Frequency 30 - 300 GHz
General Principles of VHF Propagation and Allocation of Frequencies
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1. The student should already appreciate, from the Aircraft General Knowledge Syllabus, that
the various factors which affect the transmission distance of a radio wave or transmitter power, type
of surface over which propagation takes place, frequency in use, atmospheric and ionospheric
interference, and the relative heights of the Tx and Rx. In addition, interference from other stations,
terrain or obstacle screening and the simultaneous preception of direct and ground reflected waves
can reduce the effective range and quality of radio transmission.
2. The propagation path for VHF radio transmissions is by direct wave, which limits the
maximum range of VHF reception to line-of-sight. At VHF frequencies therefore, the type of surface
over which propagation takes place has little effect on range, similarly atmospheric and ionospheric
interference is generally not a problem. However screening due to its terrain or obstacles can limit
range and quality. Also at longer ranges and especially at low level the reception of direct and
reflected waves can reduce signal quality.
3. Using the line of sight formula it can be seen that the maximum range at which an aircraft at
37,000 feet can receive a VHF transmission from a ground station at mean sea level will be:
(H
1
TX height H
2
Receiver height) = =
1.25 H
1
H
2
+ ) (
1.25 = 0 37 000 , + ( )
240nm =
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NOTE:
Some references use the simplified formula: which in
this example would give a range of 231 nm.
4. The basic airborne VHF set comprises a transceiver, antenna and control unit. In large
aircraft the transceiver is normally rack-mounted in a radio equipment compartment and the control
unit is panel-mounted in a position on the flight deck for convenient use. Light aircraft VHF sets
usually comprise a panel-mounted combined transceiver and control unit.
5. VHF antennae need not be very long and in large aircraft usually take the form of blade
antennae about 15 cm in length. Whip aerials are commonly used in light aircraft. In all cases the
antennae are vertically mounted and blade antennae involve complex circuitry in order to further
reduce the length so as to reduce aerodynamic drag.
Range = ( flt level) 12
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General Allotment of Frequency Band 117.975 137
MHz
NOTE:
The plan includes a general Allotment Table that subdivides the complete band
117.975 137 MHz, the chief subdivisions being the bands of frequencies
allocated to both national and international services, and the bands allocated
to national services. Observance of this general subdivision should keep to a
minimum the problem of co-ordinating national and international
applications.
6. The block allotment of the frequency band 117.975 137 MHz shall be as shown below.
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7. In the case of the new band 136 137 MHz, international applications have not yet been
agreed, and these frequencies should be brought into use on a regional basis where and in the manner
required.
Block Allotment of
Frequencies (MHz)
World-wide utilisation Remarks
a) 118 to 121.4 inclusive International and National
Aeronautical Mobile
Services
Specific international
allotments will be
determined in the light
of regional agreement.
b) 121.5 Emergency frequency In order to provide a guard
band for the protection of
the aeronautical
emergency frequency, the
nearest assignable
frequencies on either side of
121.5 MHz are 121.4 MHz
and 121.6 MHz, except that
by regional agreement it
may be decided that the
nearest assignable
frequencies are 121.3 MHz
and 121.7 MHz.
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c) 121.6 to 121.975 inclusive International and National
aerodrome surface
communications
Reserved for ground
movement, pre-flight
checking, air traffic
services clearances,and
associated operations.
d) 122 to 123.05 National Aeronautical
Mobile Services
Reserved for national
allotments.
e) 123.1 Auxillary frequency SAR See below.
f) 123.15 to 123.675 National Aeronautical
Mobile Services
Reserved for national
allotments.
g) 123.7 to 129.675 inclusive International and National
Aeronautical Mobile
Services
Specific international
allotments will be
determined in the light
of regional agreement.
h) 129.7 to 130.875 inclusive National Aeronautical
Mobile Services
Reserved for national
allotments but may be
used in whole or in part,
subject to regional
agreement.
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Frequency Separation and Limits of Assignable
Frequencies
8. The minimum separation between assignable frequencies in the Aeronautical Mobile (R)
Service shall be 25 kHz.
NOTE:
It is recognised that, in some regions or areas, 100 kHz or 50 kHz channel
spacing may provide an adequate number of frequencies suitably related to
international and national air services and that equipment designed specifically
for 100 Khz or 50 kHz channel spacing will remain adequate for services
operating within such regions or areas.
9. In the band 117.975 137 MHz, the lowest assignable frequency shall be 118 MHz and the
highest 136.975 MHz.
i) 130.9 to 136.975 inclusive International and National
Aeronautical Mobile
Services
Specific international
allotments will be
determined in the light
of regional agreement.(See
remark above regarding the
band 132-137 MHz)
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Frequencies Used for Particular Functions
Emergency Channel
10. The emergency channel (121.5 MHz) shall be used only for genuine emergency purposes, as
broadly outlined in the following:
(a) to provide a clear channel between aircraft in distress or emergency and a ground
station when the normal channels are being utilised for other aircraft;
(b) to provide a VHF communication channel between aircraft and aerodromes, not
normally used by international air services, in case of an emergency condition arising;
(c) to provide a common VHF communication channel between aircraft, either civil or
military, and between such aircraft, and surface services, involved in common search
and rescue operations, prior to changing when necessary to the appropriate frequency;
(d) to provide air-ground communication with aircraft when airborne equipment failure
prevents the use of the regular channels;
(e) to provide a frequency channel for the operation of survival radio equipment or
emergency location beacon aircraft (ELBA), and for communication between
survival craft and aircraft engaged in search and rescue operations;
(f) to provide a common VHF channel for communication between civil aircraft and
intercepting aircraft or interceot control units and between civil or intercepting
aircraft and air traffic services units in the event of interception of the civil aircraft.
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NOTE:
The use of the frequency 121.5 MHz for the purpose outlined in c) above is to
be avoided if it interferes in any way with the efficient handling of distress
traffic.
NOTE:
The current Radio Regulations make provisions that the aeronautical
emergency frequency 121.5 MHz may also be used by mobile stations of the
Maritime Mobile Service, using A3E emission to communicate on this
frequency for safety purposes with stations of the Aeronautical Mobile Service
(RR 593, 2990 and 2991).
11. The frequency of 121.5 MHz shall be provided at:
(a) all area control centres and flight information centres;
(b) aerodrome control towers and approach control offices serving international
aerodromes and international alternate aerodromes; and
(c) any additional location designated by the appropriate ATS authority,
12. where the provision of that frequency is considered necessary to ensure immediate reception
of distress calls or to serve the purposes specified above.
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Air-to-air Communications Channel
13. Subject to regional air navigation agreement, an air-to-air VHF communications channel shall
be designated to enable aircraft engaged in flights over remote and oceanic areas out of range of VHF
ground stations to exchange necessary operational information and to facilitate the resolution of
operational problems.
NOTE:
The assignment of the frequency to be used for the VHF air-to-air
communications channel is intended to be co-ordinated whenever necessary
between adjacent regions.
Auxiliary Frequencies for Search and Rescue Operations
14. Where a requirement is established for the use of a frequency auxiliary to 121.5 MHz, the
frequency 123.1 MHz shall be used.
Utilisation in the Band 108-117.975 MHz
15. The block allotment of the frequency band 108-117.975 MHz shall be as follows:
16. Band 108-111.975 MHz:
(a) ILS Localiser.
(b) VOR provided that:
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(i) no harmful adjacent channel interference is caused to ILS;
(ii) only frequencies ending in either even tenths or even tenths plus a twentieth of
a megahertz are used.
Band 111.975-117.975 MHz: VOR.
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Self Assessed Exercise No. 3
QUESTIONS:
QUESTION 1.
What is the minimum separation between assignable frequencies in the Aeronautical Mobile Service?
QUESTION 2.
What are the nearest assignable frequencies above and below 121.5 MHz?
QUESTION 3.
What is the auxiliary search and rescue frequency?
QUESTION 4.
What frequency band does VHF cover?
QUESTION 5.
What band of frequencies is allocated to ILS localisers and VORs, and how would you recognise a
VOR frequency in this band?
QUESTION 6.
What is the difference between Estimated Time of Arrival and Expected Approach Time?
QUESTION 7.
During a straight-in approach, when may a long final call be omitted?
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QUESTION 8.
What is the callsign used by a direction-finding station?
QUESTION 9.
Abbreviate the following callsigns: a. G-BALL b. N61058 c. N342VD d. Caledonian 451
Cessna G-CLUB
QUESTION 10.
If an aircraft fails to establish radio contact with a ground station, what is the first action which
should be taken?
QUESTION 11.
If, following the above procedure, comms failure is suspected, what are the next four points which
should be checked?
QUESTION 12.
If it is suspected that lack of communication is due to aircraft equipment failure, what procedure
should now be followed, and why?
QUESTION 13.
Following comms failure, what is the full SSR code to be used?
QUESTION 14.
Define the state of distress
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QUESTION 15.
Define the urgency message
QUESTION 16.
What is the morse code for distress?
QUESTION 17.
Can emergency incidents be practised on 121.5 Mhz, and can the state of distress be practised also?
QUESTION 18.
During a practise emergency, should SSR code A7700 be used?
QUESTION 19.
Write out the full distress message in the correct order
QUESTION 20.
In a weather report, with reference to cloud, what is the difference between scattered and
broken?
QUESTION 21.
What is a Metar?
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ANSWERS:
ANSWER 1.
25 KHz
091 Chap 7 page 7-5
ANSWER 2.
121.4 MHz and 121.6 MHz
091 Chap 7 page 7-4
ANSWER 3.
123.1 MHz
091 Chap 7 page 7-4
ANSWER 4.
30 300 MHZ
091 Chap 7 page 7-1
ANSWER 5.
108 117.975 MHz. VOR frequencies will end in even tenths
091 Chap 7 page 7-7
General Principles of VHF Propagation and Allocation of Frequencies
Chapter 7 Page 16 G LONGHURST 1999 All Rights Reserved Worldwide
ANSWER 6.
ETA the time at which the pilot estimates that the aircraft will be over a specific location
ETA the time at which ATC expects that an arriving aircraft, following a delay, will leave the
holding point to complete its approach for landing
091 Chap 1 page 1-4
ANSWER 7.
When an ILS is installed the call outer marker may be used instead.
ANSWER 8.
Homer
091 Chap 2 page 2-20
ANSWER 9.
a. G-LL
b. N058
c. N2VD
d. No abbreviation
e. Cessna UB
091 Chap 2 page 2-22
General Principles of VHF Propagation and Allocation of Frequencies
Chapter 7 Page 17 G LONGHURST 1999 All Rights Reserved Worldwide
ANSWER 10.
Attempt to establish contact with other aircraft or stations on frequencies appropriate to the route
091 Chap 5 page 1
ANSWER 11.
the correct frequency has been selected
the station being called is open for watch
the aircraft is not out of radio range
the receiver volume is correctly set
091 Chap 5 page 1
ANSWER 12.
Messages should be transmitted twice on the designated frequency, preceded by the phrase
TRANSMITTING BLIND, in case the transmitter is serviceable
091 Chap 5 page 1
ANSWER 13.
A7600 + C
091 Chap 5 page 2
General Principles of VHF Propagation and Allocation of Frequencies
Chapter 7 Page 18 G LONGHURST 1999 All Rights Reserved Worldwide
ANSWER 14.
A condition of being threatened by serious and/or imminent danger and of requiring assistance
091 Chap 6 page 1
ANSWER 15.
A condition concerning the safety of an aircraft or other vehicle, or of some person on board or
within sight, but not requiring immediate assistance
091 Chap 6 page 1
ANSWER 16.
_ _ _
091 Chap 5 page 1
ANSWER 17.
Yes, no
091 Chap 6 page 8
ANSWER 18.
No, unless required by the controller
091 Chap 6 page 9
General Principles of VHF Propagation and Allocation of Frequencies
Chapter 7 Page 19 G LONGHURST 1999 All Rights Reserved Worldwide
ANSWER 19.
MAYDAY MAYDAY MAYDAY
Name of station addressed (when appropriate and time and circumstances permitting)
callsign
Type of aircraft
Nature of the emergency
Intention of the person-in-command
Present or last known position, flight level/altitude, and heading
Any other useful information
Note: In the UK, pilot qualifications should be included whenever possible as it may help the
controller
091 Chap 6 page 5
ANSWER 20.
Scattered = 3 or 4 octas
Broken = 5-7 octas
091 Chap 4 page 1
General Principles of VHF Propagation and Allocation of Frequencies
Chapter 7 Page 20 G LONGHURST 1999 All Rights Reserved Worldwide
ANSWER 21.
A routine meteorological aerodrome report
091 Chap 4 page 1