Time Calculation

UNIT 3 TIME CALCULATION

Structure

3.0 Objectives
3.1 Introduction
3.2 Imaginary lines on Earth
3.3 World Time Zones
3.3.1 Prime Meridian and Standard Meridian
3.3.2 Greenwich Mean Time/ Universal Time Coordinated
3.3.3 Standard Clock Time and Daylight-Saving Time
3.4 International Time Calculator
3.4.1 Multiple Time Zone countries
3.5 Time difference between Two Cities
3.6 International Date Line
3.6.1 Importance of International Date Line
3.7 Elapsed Flying Time
3.7.1 Calculation of Elapsed Flying Time
3.7.2 Jetlag
3.8 Let Us Sum Up
3.9 Further Readings
3.10 Clues to Check Your Progress Exercises
3.11 Activities

3.0 OBJECTIVES
After reading this unit you will be able to:
 understand the worldwide time system,

 get clarity on why there are time differences in different areas of the world,
 calculate the local time of a city or area corresponding to GMT/UTC,
 calculate the time differences between two regions; and
 find the elapsed flying time.

3.1 INTRODUCTION
Ever since humans first noticed the movement of sun and earth, time was
calculated based on the position of the sun. Every place was following their local
clock till the time people started travelling, specially inter– continental travel. Once
people started traveling across continents using various travel modes, and crossing
major distances; there arose confusion with regard to the time. Due to the
continuous rotation of the earth, cities have day and night at different times. For
example, when it is day in India, it’s night in
Canada. Someone who lives very far away can be just a few hours ahead of you. A 37
Airport Handling passenger after traveling 24 hours, when reaches a city, finds that the local timing of
the city clock is a time little ahead of the same day as starting the journey. While
on the other hand, after a short hour of journey, on reaching the destination, the
place shows a time which is one day ahead. How can it happen? It happens
because countries/ regions set different times in the clock based on their location.
These are all based on the rotation of earth on its own axis. International travel
and business depend on a worldwide time system. In this unit we will explain the
concept of earth’s rotation and its impact on time calculation. We will also discuss
terms like world time zones, prime meridian, standard time zones etc. to set
global standards in time calculation.

3.2 IMAGINARY LINES ON EARTH

As you have studies in Unit 2, we have certain imaginary lines on earth that gives us
the different Hemispheres. There are few other such imaginary lines of
reference. For example, the spinning of the earth on its axis from west to the east
provides us with two natural points of reference, i.e. North and South Poles. At the
same time for identifying the location of a place, a network of intersecting
imaginary lines is drawn - one as horizontal and another one as vertical on the
surface of earth. These imaginary lines are called Parallels of Latitudes (Latitude)
and the Meridians of Longitudes (Longitude) respectively. They are referred to
as geographical coordinates as they represent a systematic network of lines upon
which the position of various surface features of the earth is dependent. With the
help of these lines, the location, distance, and direction of various points can be
easily determined. Latitudes and longitudes are measured in degrees (°) because
they represent angular distances. Each degree is further divided into 60 minutes (‘)
and each minute into 60 seconds (“). Using these as parameters of time, one can
calculate time of a place location.
1. Equator
The imaginaryplanetary line drawn midwaybetween the North Pole and the
South Pole is called the equator. It is the largest circle and located halfway
between the North Pole and the South Pole. This invisible line that runs around
the center of the Earth at 0° latitude divides the globe into two equal halves-
Northern Hemisphere and Southern Hemisphere. It is also called a great circle
since the earth is widest at its Equator. The distance around Earth at the
Equator(circumference) is 40,075 kilometers (24,901 miles).
All otherparallel lines get smaller insizewhenmovingtowardsthepoles, in
proportion to their distance from the equator. Distance between the zones is
the greatest at the equator while at the poles it reduces due to the curvature
of earth. As the circumference of the equator is approximately 24,901 miles
the distance between the time zones at the equator is approximately 1,038
miles.
2. Latitudes
Latitudes are horizontal lines parallel to the equator on earth’s surface. They
run east and west around the globe and tell us the distance either north or south
of the Equator. Lines joining places with the same latitudes are called parallels.
The value of equator is 0° and the latitude of the poles are 90°N and 90°S.
as mentioned earlier, Equator is the 0°line and splits earth into two equal
halves as northern and southern hemispheres. Each hemisphere is divided into
 90 degrees, from the Equator
38 to the Pole. Lines of latitude get smaller as they get further towards the pole.
 Time Calculation

Figure 3.1 Imaginary lines on Earth’s Surface

In addition to Equator, there are four other major latitudes that are usually found
on maps and globes. The positions of these four latitudes are determined by the
Earth’s axial tilt.
a) The latitude 23° 262 North is also known as the Tropic of Cancer. It
marks the region north of equator on the Earth, where the Sun is directly
overhead at least once a year.
b) The Tropic of Capricorn is the latitude that lies at 23° 262 South of
the Equator. It is the position on the globe, where the Sun is directly
overhead during December
c) The Arctic Circle is the latitude 66° 342 North. All locations falling north
of this latitude are said to be in the Arctic Circle.
d) The Antarctic Circle, on the other hand, is the latitude 66° 342 south.
Any locations in the globe falling south of this latitude are said to be in the
Antarctic Circle.
Places in both the Arctic and Antarctic circles experience the Midnight Sun and polar
night.
3. Longitudes
The meridians of longitude are semicircles that run from pole to pole around
the globe and tells us the distance, east or west, from the Prime-Meridian.
In case opposite meridians are taken together, they complete a circle, but they
are valued separately as two meridians. The meridians intersect the equator at
right angles. They begin at the Prime Meridian and split the Earth into East
and West hemispheres. Unlike the parallels of latitude, they are all equal in
length. For the convenience of numbering, the meridian of longitude passing
through the Greenwich Observatory(near London) has been adopted as the
‘Prime Meridian’ by an international agreement and has been given the
value of 0°.
The longitude of a place is its angular distance east or west of the Prime
Meridian. It is also measured in degrees. Longitudes vary from 0° to 180°
eastward and westward of the Prime Meridian. The east portion of the Prime
Meridian is called the eastern hemisphere and in the west portion is referred
to as the western hemisphere. All the other longitudes are measured and named
after the angle they make with respect to the center of the Earth from the
intersection of the Meridian
and the Equator. 39
Airport Handling Since a sphere has 360 degrees, the Earth is divided into 360 longitudes. The
meridian opposite the Prime Meridian (on the other side of the Earth) is 180°
longitude and is known as the anti - meridian. Modern timekeeping systems use
longitudes as references to keep time. Therefore, time zones are defined by the
Prime Meridian and the longitudes.

3.3 WORLD TIME ZONES

The acceptance of the idea of time zones took almost a century. Until the 19th
century, each city followed its own local clock. Sir Sanford Fleming, a Scottish
Canadian engineer took the pain of arguing for a standard time and for an
international agreement on prime time. In 1888, the United Nations and
Canada adopted a standard time. In 1884, the International Meridian
Conference was held in Washington DC. United States to determine a meantime
in the world. 27 countries attended the conference, and major nations agreed to
use Time Zone Systems.

To understand this concept of time zone, let us understand the shape of the earth.
Earth is a sphere that spins on an imaginary axis and makes a complete rotation in
24 hours; which is called a complete day. When the earth rotates, parts of the
earth receive sunlight and experience day, while the other side experiences night.
In 24 hours, each place experiences day and night, but at different times. In some
cases, due to different geographical, social and/or political reasons, time zones may
deviate from the universal standards and recommendations as set by international
institutions. Governments often set timedifferently. For example, some countries have
multiple time zones (likeAustralia), few others have colonial past and territories are
miles away from the mainland (like France) and few large countries like China
have only one time zone regardless of the territories.

3.3.1 Prime Meridian and Standard Meridian

The International Meridian conference chose the royal observatory at
Greenwich, London, England as the place of Prime Meridian i.e. 0° longitude.
Thus, a world standard was set at Greenwich. Based on earth rotation, the solar day
has been divided into 24 hours and hence, the earth is divided into 24 imaginaryzones
each corresponding to one hour of earth’s rotation. These imaginary zones are called
time zones, beginning with the prime meridian in Greenwich. There are 24
longitudes in total, each at 15- degree intervals called Standard Meridians.
Earth revolves 360 every 24 hours or 15 per hour (360/24=15). Hence each
standard meridian has a longitudinal difference of 15 and a time difference of 1
hour. The Prime Meridian is considered as the reference zone for the calculation of
time and is known as 0° meridian, Greenwich meridian, or prime meridian of the
world.

For example, the longitudinal value of New Delhi is 82.5° E (82.5° behind
Prime Meridian). As said earlier, each 15° longitude constitutes one hour difference
in time zone. Hence, the hour difference from Prime Meridian can be calculated as a
longitudinal value divided by 15° i.e., 82.5°/15 = 5.5 hours. This means New Delhi is
05 hours and 30 minutes ahead of Prime Meridian since New Delhi is located East of
Prime Meridian. Sun rises in the East, hence location in East is ahead of Prime
Meridian while west is behind Prime Meridian.
40
 Time Calculation

Figure 3.2: Prime Meridian and International Date Line

3.3.2 Greenwich Mean Time/ Universal Time Coordinated

The time at Greenwich and all the countries in this zone is referred to as
Greenwich Mean Time (GMT); also known as Universal Time Coordinated (UTC).
The time in all other zones can be expressed by referring to GMT or UTC. As it
moves eastwards from the prime meridian, with every standard meridian there is
an addition of 01 hour in the time. If it is 12 noon at Prime Meridian, the time at the
first standard meridian on the right will be 1 pm. Similarly, when it moves
towards the west, 1 hour decreases with each standard meridian. When it is 12 noon
at the prime meridian, the first standard meridian on the west shows the time as 11
am. The sign + (plus) and -(minus) are used to mention the time relative to
GMT/UTC.
GMT+1 =1 Hour ahead of GMT (Towards the east of GMT)
GMT-1 =1 Hour behind GMT(Towards west of GMT) up to GMT +12 and
GMT-12.
3.3.3 Standard Clock Time and Daylight-Saving Time
Depending on the location and the size of a country, few countries fall in different
time zones. In order to maintain the same local time within the national
boundaries of a country, a time is fixed by law, called Standard Clock Time
(SCT) or Standard Time. Prime Meridian is considered as the reference zone for
the calculation of time and known as 0° meridian, Greenwich meridian, or prime
meridian of the world.
India falls between the longitude of 68° 7" E and 97° 25" W; officially Indian
standard time is designated at 82.5° E or GMT+ 05.30, which is 5 hours 30 minutes
ahead of GMT.
Certain countries modify their standard time during summer by advancing one hour
or a fraction of an hour. This is a way of making better use of the natural dayli
setting the clock forward during the summer months, and back again in autumn.
This temporary change is called Daylight Saving Time (DST). Example: The 41
standard clock time in
Airport Handling Germany is one hour ahead of GMT(GMT+1). Germany modifies the standard
time by advancing one hour from 27 March to 30 October every year, thus the
standard time becomes 2 hours ahead of GMT (GMT+2)

Check Your Progress-1

1. What is the significance of Longitudes and Latitudes?

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2. What is the Time Zone system?
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3. Why are UTC /GMT considered as the reference time zone?
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3.4 INTERNATIONAL TIME CALCULATOR

Time charts are published in all major airline guides. The OAG time calculator given
in the chart in the annexure, lists all country/area wise Standard Clock Time,
Daylight Saving Time and Daylight Saving Time effective periods. Standard
Clock Time is expressed in hours ahead (+) or behind (-) of GMT. Few examples
to find the local time of a city, when GMT is known are given below.

Example 1:

What is the local time in Colombo (CMB), Srilanka when it is 1200 hours GMT?

Answer: In Sri Lanka, the standard time is GMT +6 all year around. This means
that the local time is 6 hours ahead of GMT. Hence, when it is 1200 GMT, local
time in Srilanka is 1800 hours(1200+6).

Figure. 3.3
42
Example 2: Time Calculation

What is the local time in Caracas (CCS), Venezuela when it is 1200hrs GMT?
Answer: Here, it is indicated in the International Time Calculator that the
Standard Clock time of Venezuela is GMT -4 throughout the year. The local
time is 4 hours behind GMT. Hence it is 0800 hours (1200- 4) in Caracas,
when it is 1200 hours GMT

Figure: 3.4

Example 3:
What is the local time of Frankfurt on 1 April when it is 12 00 hours GMT?
Answer: The Standard Local Time of Germany is GMT +1 and the Daylight-
Saving time from 31 March to 26 October is GMT+2. That means, on 1 April, the
local time is 2 hours ahead of GMT and therefore it is 1400 hours in Frankfurt
when it is 1200 hours GMT.
Example 4:
What is the local time in Lagos (LOS), Nigeria when it is 1600 hours local time in
Beijing (BJS), China on 22 March?
Answer: In Nigeria, on 22 March the local time is GMT+1, In China, the local time is
GMT+8
This means that the local time in China is 7 hours ahead of the local time of
Nigeria (8- 1=7). Hence, if it is 1600 hours local time in Beijing, it will be
0900 hours in Nigeria on the same day. If GMT+8= 1600 hours, GMT=1600-8=
08 hours. Local time in Lagos is GMT+1 , that is 0800+1= 0900 Hours

Figure: 3.5

Example 5
What is the local time in Milan, Italy when it is 0230 in La Paz, Bolivia on 27 May?
Answer: The local time in Italy on 27 May is GMT +1, on the same day the local
time in Bolivia is GMT-4. That means the local time in Italy is 5 hours ahead of
Bolivia (+1 – 4 = 5). Therefore, when it is 0230 hours in La Paz, it is 0730
hours (0230 +5) in
Milan on the same day. 43
Airport Handling

-4 +1 +8

LAP Difference 5 hours MXP

Figure: 3.6

3.4.1 Multiple time zone countries

Some countries have many time zones. Large countries such as the USA,
Australia, Canada, Brazil, Greenland, Indonesia, the Russian Federation, have
their territories spread over several time zones and hence different standard times
have been established for different areas/states within the county. These multi-time
zone countries have been marked by two asterisks (**) in the OAG International
Time Calculator. The largest country in the world Russiahas11 time zones and
France, a smaller country, has 12 time zones while Brazil has three different
time zones.
One example for reference is that of the Country Canada which uses 6 primary
time zones from east to west, namely, Newfoundland time, Atlantic time, Eastern
time, Central time, Mountain time and Pacific time. Most of Canada works on
standard time from 7 November to 12 March and daylight-saving time for the

Offset Time Zone Example city

UTC/GMT-8 Pacific Standard Time Vancouver
UTC/GMT-7 Mountain Standard Time Edmonton
UTC/GMT-6 Central Standard Time Winnipeg
UTC/GMT-5 Eastern Standard Time Toronto
UTC/GMT-4 Atlantic Standard Time Halifax
UTC/GMT-3:30 Newfoundland Standard Time St. Johns Example
China on the other hand is using 5 different time zones, still the countryfollows a
single time that is Beijing standard time. After the collapse of the Qing Dynasty in
1912, the newlyempowered Republic of China established five different time zones in
the country, but in 1949, Mao Zedong declared that all of China would henceforth
be on Beijing time (GMT+8) for the purposes of national unity.

While, in the USA, the standard time is GMT-5 in the Eastern zone, GMT-6 in
Central time, GMT-7 in Mountain time, GMT- 8 in Pacific time, GMT-9 in
Alaska, GMT-10 in the Aleutian Islands and Hawaiian Islands. It is GMT-8 in
Pacific zone from 13 March to 06 December, Daylight saving time is applicable to
all areas except Arizona and Hawaiian Islands (one hour behind the standard
time)

44 Figure 3.7 USA Time zones

 Time Calculation
3.5 TIME DIFFERENCE BETWEEN TWO CITIES
Calculation of time difference is one of the most important parts of international
travel. One can either gain or loss time while traveling across international borders
and time zones. Let us now find out how to calculate time difference between two
points/ cities. If the local time of the two cities is known, time difference between
the points can be easily determined. In case the local time in both the points is
ahead of GMT or behind GMT, deduct the smaller from the largest figure. For
example: Time difference between the places having local time GMT+3 and
GMT+9. Time difference = 9 - 3 i.e. 6 Hours

06 hours

Figure: 3.8

If the local time is ahead of GMT at one point and behind GMT at another point,
add both the figures together. Example: - 0 GMT+ 4 and GMT -8. So, 4+ 8 =12
hours difference between the points

12 hours

Figure 3.9

Example 1:
Determine the time difference between Manila (MNL), Philippines and Beijing
(BJS), China.
Answer: The Local time in Philippines is GMT+8 and China is also GMT+8
The time difference between MNL and BJS is 8-8=0. Both the places belong to
the same time zone and have the same local time.
Example 2:
Determine the local time between Kingston (KIN), Jamaica and Johannesburg
(JNB), South Africa
Answer: The Local time in Kingston is GMT-5 and Johannesburg is GMT+2 The
time difference between KIN and JNB is 5+2=7 Hours
Example 3:
When the local time in Tunis (TUN), Tunisia on 5 November is 0330 hours,
what is the local time and date in Kathmandu (KTM), Nepal? 45
Airport Handling Answer:
Tunisia local time is GMT+1
Nepal Local time is GMT+5.45
As the local time in both the places are ahead of GMT(GMT+), deduct the
smaller figure from the larger one.
Kathmandu GMT+5.45 -
Tunis GMT+1
Difference: 4 hours 45 minutes
Hence, the local time in Kathmandu is 4 hours 45minutes ahead of Tunis.
When the local time in Tunis is 0330 hours on 5 November, it is 0800 hours on
the same day in Kathmandu.
Example 4
The local time in Dhaka (DAC) Bangladesh is 1500 hours on 21 May, what is the
local time and date in Honolulu (HNL), Hawaiian Islands, USA?
Answer:
Local time in Dhaka, Bangladesh is GMT+6
Local time in Honolulu, Hawaiian Islands is GMT-10
As the local time is ahead of GMT(GMT+) at one point and behind GMT(GMT-)
at the other, add both the figures together.
The time difference between DAC and HNL is 16 Hours (6+10)
The local time in Honolulu is 16 hours behind Dhaka. That is, 1500hours-16 hours
=2300 hours the previous day (20 May)

Figure: 3.10

3.6 INTERNATIONAL DATE LINE (IDL)

As you are now aware, Prime Meridian at 0° longitude passes through
Greenwich, England. There are 24 standard meridians, 12 are towards the west
side of the Prime Meridian and 12 are towards the east side of the Prime Meridian.
Starting from 0°, the east meridian ends at 180°, which is known as 180° East, similarly,
from 0°, the west meridian ends at the same 180° and calls it 180° west; although
it is the same imaginary line.
The International Date Line (IDL) is an imaginary line on Earth’s surface at 180°
46 longitude, located halfway around the world from the prime meridian (0° longitude) or
about 180° east (or west) of Greenwich Observatory. Since the lines are not straight Time Calculation
as it appears, it is also called the ‘Line of Demarcation’. The time at this longitude
is exactly 12 hours from the 0° longitude, irrespective of whether one travels
westward or eastward from the Prime Meridian. As the earth moves from west to
east, one who moves back to the west by crossing the Prime Meridian is going
back to the time (gains time)and if one moves forward towards the east by crossing
the prime meridian goes ahead of the time(loses time).
Crossing IDLmakes the calculation of time difference a little complicated since
travelers either gain or lose a day during the process. Time increases east of the
Prime Meridian and decreases to its west. Therefore, when a person crosses the
IDL traveling towards west the daychanges to the following day-Mondaywould
immediatelybecome Tuesday. Passenger crossing IDLgoing east gains a day, which
means for him Tuesday becomes Monday.
The International Date Line (IDL) or the line of demarcation is the boundary
between one day and the next. This line runs from the North Pole to the South Pole
and marks the divide between the Western and Eastern Hemisphere. It is not
straight but zigzags to avoid political and country borders as well as to avoid cutting
some countries in half. East and West of IDL the date differs, and hence the must
be considered as a wall which cannot be crossed when calculating the time
difference.
For example, a passenger departs on Wednesday morning from Honolulu to
Tokyo. She/He can reach within 9 hours by flight, but it would be the next day, i.e.
Thursday in Tokyo as the International Date Line is crossed from east to west
(loses a day). Similarly, if someone travels from Tokyo on a Wednesday morning
and comes back to Honolulu, he will arrive on Tuesday because the International
Date Line is crossed by traveling west to east (gains a day).

3.6.1 Importance of International Dateline

International Date Line brings coordination between international airlines,
transportation services, economic and trade activities. The accurate calculations of
the day and time are possible due to IDL. The International Date Line has no legal
international status and countries are free to choose the dates that they observe.

Figure. 3.11 : International Date Line 47

Airport Handling Example 1: Apassenger who flew from Hong Kong (HKG) on 2 September at
1230 hrs reached Los Angeles (LAX) after 12 hours 20 minutes in a nonstop
flight.
The expected time of arrival is 0020 hrs on 3 September. Upon arrival, he had
to adjust his clock to 2050 hrs on 02 September. How did he reached a day earlier
than expected?

Figure: 3.12

Answer: The local time in Hongkong is 8 hours ahead of GMT/UTC(GMT+8)

and Los Angeles is 8 hours behind GMT(GMT-8). The time difference between
the cities is 16 hours (8+8). Hongkong is 16 hours ahead of Los Angles. So
actually, when the flight departed, it was 16 hours behind the actual time of
Hongkong, which is 2030 hrs on 1 September. When the travel time is added the
time becomes 2050 hrs on 2 September.

This is because the passenger crossed the International Dateline from east to
west while traveling from Hongkong to Los Angeles and hence he gained a
day.
Example 2: Nadi (NAN) in Fiji and Apia(APW) in Samoa are islands very close
to each other, around 1,225 km. But when it is Sunday in Nadi, it is Saturday in
Apia. Why is this difference in time between these two neighboring islands?
Answer: Samoa, the local time is GMT-11. There is a difference of 23 hours here.
The local time in Nadi is 23 hours ahead of Apia.
Nadi and Apia are separated by the International Dateline. When the IDL is
crossed eastbound (from Nadi to Apia) a day is gained. For example, a passenger
flying from Nadi on Monday, reaches Apia in two hours, but when reaches it will
be Sunday in Apia.

When IDL is crossed westbound (From Apia to Nadi), one loses a day. For
example, a passenger flying from Apia on Monday, reaches Nadi in two hours, but
when reaches it will be Tuesday in Apia.

Figure: 3.13

It is to be noted that International Dateline can not be crossed while calculating

the time difference. It can be done only by using GMT/UTC.
48
 behind GMT
3.7 ELAPSED FLYING TIME (GMT- 4 Eastern,
daylight-saving
The transport time is the number of hours and minutes from the time of departure at time). Therefore, the
the airport of origin until the time of arrival at the airport of final destination. This flight departed from
includes eventual transit and/or transfer times. This is also known as Elapsed New York when it
Flying time. was 0055 hours
Elapsed Flying time is the time between the departure and arrival times – ramp to GMT
ramp – in minutes. This includes any stopover time if the flight involves one or (2055+4=0055
hrs.)
more stops.
Elapsed time is an important concept in Air transportation, especially with
long international air travel. In such journeys, long distances are covered in a short
time and different time zones are crossed when they travel to regions with different
time zones. It sometimes creates confusion regarding the time. Passengers may have
to adjust their watches after arrival. If the origin and destination fall in different time
zones, calculating the travel time is also not so easy. The city’s local times have
to be converted into GMT/UTC, and then the difference could be calculated.

Example: A passenger who flew from Hong Kong (HKG) on 2 September at

1230 hrs. reached Los Angeles(LAX) after 12 hours 20 minutes in a nonstop
flight. The expected time of arrival is 0020 hrs. on 3 September. Upon arrival, he
had to adjust his clock to 2050 hrs on 02 September. He reached a day earlier
than expected.
The local time in Hongkong is 8 hours ahead of GMT/UTC (GMT+8) and Los
Angeles is 8 hours behind GMT(GMT-8). The time difference between the cities is
16 hours (8+8). Hongkong is 16 hours ahead of LosAngles. So actually, when the
flight departed, it was 16 hours behind the actual time of Hongkong, which is 2030
hrs on 1 September. When the travel time is added the time becomes 2050 hrs
on 2 September.

3.7.1 Calculation of Elapsed Flying Time

The Elapsed Flying Time (transport time) is the number of hours and minutes from
the time of departure at the airport of origin until the time of arrival at the airport
of final destination. This includes eventual transit and/or transfer times. Elapsed
Flying Time is the time between the departure and arrival times – ramp to ramp –
in minutes. This includes any stopover time if the flight involves one or more stops.
Calculating Elapsed time is an important concept in air transportation, especially in
long international travel. There are confusions regarding the travel time when origin
and destination cities belong to different time zones. Hence, when there is a time
difference between origin and destination cities, both the local times need to be
converted into GMT/UTC before calculating the travel time.
Example 1: Flight departs from New York on 9 September at 2055 hrs. and
reaches Doha, Qatar on 10 September at 1625 hrs. What is the Elapsed flying
time?
Answer: New York and Doha are located in two different time zones and hence
we can’t add or subtract the local times.
The first step to find elapsed flying time for any flight schedule, departure, and
arrival time need to be changed to GST/UTC. In this flight schedule, New York and
Doha are in different time zones. The local time in New York, USA is 4 hours
Time Calculation

49
Airport Handling The GMT/UTC time in New York is when the local time of Doha, Qatar is 3
hours ahead of GMT(GMT+3). So, the flight arrived at Doha, Qatar when it
was 1325 hours GMT. (1625-3=1325 hrs) on 10 September. The Elapsed flying time
is calculated by subtracting the departure time from arrival time (in GMT).Arrival
time in GMT is 1325 hours, 10th September and departure time in GMT is 0055
hours 9th September. Elapsed flying time=Arrival Time-Departure time (in
GMT) which is 12hours 30minutes.

Example 2: A flight departs Sydney on 10 June at 2055hrs and reaches

London Heathrow Airport at 1620 hours, the next day. What is the Elapsed flying
time of the journey?
Answer: The local time in Sydney, Australia is 10 hours ahead of
GMT(GMT+10) The local time in London, UK is GMT time
Hence it is clear that the flight departed from Sydney when it is 1055 hours
GMT (20:55-10=10:55) on 10 June and arrives London when it is 1620 hours
GMT on 11 June
Elapsed time=Arrival time-departure time (in GMT) i.e. 1620 hours (on 11
June)- 1055 hours (on 10 June) =29 Hours 25 Minutes (Add 24 hours to the
difference 05 hours 25minutes)
Example 3: A flight departs from Singapore on 17 June at 2210 hrs and
reaches Vancouver on the next day at 1450 hrs. Calculate the Elapsed flying
time.
Answer: The local time in Singapore is 8 hours ahead of GMT (GMT+8). The
flight departed Singapore at 1410 hours GMT (2210-8) on 17 June.

The local time in Vancouver, Canada is 7 hours behind GMT(GMT-7, Pacific

Daylight- Saving time). The arrival time in GMT is 2150 hours (1450 +7) on 18
June.
Elapsed flying time= (2150+ 24) -1450=31 Hours. (24 hours is added as the arrival
is on the next day)
Usually, flight arrivals one day before and/or after are highlighted in airline
timetables by special signs printed next to the time of arrival at the destination.

3.7.2 Jetlag
Jetlag is the temporary sleeping disorder experienced when someone is traveling
in different time zones. Jet Lag is caused by disruption of the ‘body clock’ and
affects most air travelers crossing five or more time zones. Fatigue and related
symptoms are experienced by travellers when taking long airline trips, and while
crossing multiple time zones. The ‘internal clock’ of the body gets confused
when the time zones are changed. As and when a passenger flies from San
Francisco to Rome which has a difference of 9 time zones, the body does not
understand the difference and hence may wake up in the middle of the night or
may feel sleepy during daytime. The incidence and severity of jet lag increase
with the number of time zones. Sleepiness, insomnia, headache, indigestion,
irritability, or lack of concentration are common for those who have jetlag. It is
observed that these symptoms persist for one day per time zones crossed and it
varies from person to person.
50
 Time Calculation
Check Your Progress-2

1. How to determine the time difference between two cities if the local times
are known?
....................................................................................................................
....................................................................................................................
....................................................................................................................
2. What is the International Date Line? Why is the International Date Line important?
....................................................................................................................
....................................................................................................................
....................................................................................................................
3. How is Elapsed Flying Time calculated?
....................................................................................................................
....................................................................................................................
....................................................................................................................
4. What is Jetlag?
.....................................................................................................................
....................................................................................................................
....................................................................................................................

3.8 LET US SUM UP

At any given moment, time would be different in different places / cities of the
world. Knowledge about a few imaginary lines is important to understand the
concept of time difference. These imaginary lines namely, the Equator, Prime
meridian, Longitudes, Latitudes, and International Datelines explains the worldwide
time system. As people started traveling long distances in a short time, the idea
of solar time was replaced through the Internationally accepted Greenwich
Mean Time/Universal Time Coordinated. By following this GMT, the
complexities of time differences were easily overcome. The idea of time zones
defines and establishes appropriate time within counties/regions, which
practically has an enormous impact on Transport, business, communication and
world management. It is imperative for a tourism professional to know about the
time difference between cities and destination to be successful.

3.9 FURTHER READINGS

1. IATA Course study material & E- Library Publications
2. Boniface, B. G., & Cooper, C. P. (2001). Worldwide destinations: The
geography of travel and tourism. Oxford: Butterworth-Heinemann.
51
 Airport Handling
3.10 CLUES TO CHECK YOUR
PROGRESS EXERCISES

Check Your Progress–1

1. See section 3.2 and frame your answer

2. See section 3.3 and frame your answer
3. See section 3.3 and frame your answer

Check Your Progress–2

1. See section 3.4 and frame your answer

2. See section 3.6 and frame your answer
3. See section 3.7 and frame your answer
4. See section 3.7 and frame your answer

3.11 ACTIVITIES
1. Identify the longitude, Latitude and the corresponding time zones of any 10
cities of the world
2. Practice to find the time difference between the major tourist destinations of
the world
3. Find any 5 travel itinerary/route where International Dateline is crossed.
4. Practice to calculate the Elapsed flying time of flights in different routes

ANNEXURE – INTERNATIONAL TIME CALCULATOR

Hour CSTDay Capital Territory, NSW +10.30

Time + (excluding Lord Howe
CGST
Afghanistan + 4.30 Islandand Broken Hill),
Albania +1 +2 27 Mar 30 Oct Victoria +10 +11 02 Oct 01 Apr
Northern Territory +9.30
Algeria Queensland +10 +10.30 02 Oc -01
Andorra +1 +2 27 Mar 30 Oct Apr South Australia, Broken Hill +9.30
Angola +1 01 Apr Western Australia
+8
Anguilla, Leeward Islands -4
Antarctica -4
Antigua and Barbuda,
Leeward Islands -4
Argentina -3
Armenia +4 +5 27 Mar 30 Oct
Aruba
Australia ** -4

52 Lord Howe Island +11 02Oct 01 Apr

Tasmania +10 +11 02 Oct 01 Apr
Austria +1 +2 27 Mar 30 Oct
Azerbaijan +4 +5 27 Mar 30 Oct
B Hours OST Day
+GST
Bahamas -5 -4 13 Mar -06 Nov
Bahrain +3
Bangladesh +6
Barbados -4
 Time Calculation
Belarus +2 +3 27 Mar 30 Oct Saskatchewan -6
Mountain areas not
Belgium +1 +2 27 Mar 30 Oct
observing DST -7
Belize -6
Cape Verde -1
Benin +1
Cayman Islands -5
Bermuda -4 -3 13 Mar -06 Nov Central African Republic +1
Bhutan +6 Chad +1
Bolivia -4 Chile **
Bonaire, Saint Eustatius and Mainland -4 -3 09 Oct -10 Mar
S aba -4 Easter Island -6 -5 08 Oct -10 Mar
China +8
Bosnia and Herzegovina +1 +2 27 Mar 30 Oct
Chinese Taipei +8
Botswana +2
Christmas Island, Indian
Brazil **
Alagias, Amapa, Bahla, Ocean +7
Ceara, Maranhao, Para, Cocos (Keeling) Islands +6.30
Paraiba, Pernambuco,
Colombia -5
Piaul,
Rio Grande do Norte, Comoros +3
Sergipe, Congo +1
Tocantins -3
Amazonas, Rondonia, Congo Democratic
Roraima, Acre, -4
Fernando De Noronha, -2 Kinshasa,ofBandundu
Republic **
Espirito Santo, Distrito Bas-Congo, Equateur +1
Parana, Rio De Janeiro, Rio Kasai, Kivu, Maniema,
Katanga, Oriental +2
Grande do Sul, Santa
Catarina, Sao Paulo -3 -2 16 Oct 25 Feb Cook Islands -10
Mato Grosso, Mato Grosso -4 -3 16 Mar 25 Feb
Costa Rica -6
do S ul
Cote D’lvoire GMT
Brunel Darussalam +8
Croatia +1 +2 27 Mar 30 Oct
Bulgaria +2 +3 27 Mar 30 Oct
Cuba -5 -4 20 Mar 30 Oct
Burkina Faso GMT
Curacao -4
Burundi +2
Cyprus +2 +3 27 Mar 30 Oct
C Hours OST Day
+GST Czech Republic +1 +2 27 Mar 30 Oct

Cambodia +7 D Hours OST Day

+GST
Cameroon +1
Denmark +1 +2 27 Mar 30 Oct
Canada **
Newfoundland Island Djibouti +3
(excluding Labrador) -3.30 -2.3013 Mar 06 Nov Dominica +4
Atlantic area including
Dominican Republic -4
Labrador -4 -3 13 Mar 06 Nov
Eastern Time -5 -4 13 Mar 06 Nov E Hours OST Day
Central Time except +GST
Saskatchewan -6 -5 13 Mar 06 Nov Ecuador **
Mountain Time Zone -7 -6 13 Mar 06 Nov Mainland -5
Pacific Time -8 -7 13 Mar 06 Nov Galapagos Islands -6
Atlantic Areas not
Egypt +2
observing DST -4
Eastern areas not E I Salvador -6
observing DST -6

53
 Airport Handling

Equatorial Guinea +1 Hong Kong (SAR) China +8

Eritrea +3 Hungary +1 +2 27 Mar - 30 Oct
E s tonia +2 +3 27 Mar - 30 Oct J Hours DST Day
E thiopia +3 GMT GMT DS
F Our OST Day Iceland GMT

+ GST India +5.30

Falkland Islands -
3 Indonesia **
Faroe Islands GMT +1 27 Mar - 30 Western including sumatera
Oct Jawa, Kalimantan Barat and
Fiji +12 Kalimantan Tengah +7
Finland +2 +3 27 Mar - 30 Oct Central including Sulawesl,
France +1 +2 27 Mar - 30 Oct Kalimantan Selatan,

French Guiana - Kalimantan Timur and Nusa

Tenggara
3 French Polynesia **
Marquesas Islands -9.30
+8
Eastern including Maluku
and Papua

French Polynesia except

Iran Islamic Republic of +3.30 +4.30 22 Mar-21 Sep
Marquesas Island and
Gambier Island -10 Iraq +3
Gambier Island -9
Ireland Republic of GMT +1 27 Mar - 30 Oct
G Hours DST Day
GMT GMT DS Israel +2 +3 01 Apr - 02 Oct

Gabon +1 Italy +2 +3 01 Apr - 02 Oct

Gambia GMT J Hours DST Day
Georgia +4 GMT GMT DS
Germany +1 +2 27 Mar - 30
Jamaica -5
Oct
Japan +9
Ghana GMT
Gibraltar +1 +2 27 Mar - 30 Jordan +2 +3 01 Apr - 27 Oct
Oct K Hours DST Day
Greece +2 +3 27 Mar - 30 Oct
GMT GMT DS
Greenland **
Greenland except Pituffik, Kazakhstan **
Ittoqqortoormiit, Nerlerit Aktau, Atyrau, Aktyubinsk
Inaat -3 -2 26 Mar - 29 Oct Uralsk +5
P ituffik -4 -3 13 Mar - 06 Almaty, Astana, Karaganda
Nov
Ittoqqortoormiit, Nerlerit Kokshetau, Kostanay,
Inaat -1 GMT 27 Mar -30 Oct Kyzl-Orda, Petropavlovsk,

Grenada, Windward Islands -4 Semipalatinsk, Shimkent,

Guadeloupe - Ust-Kamenogorsk +6
4 Kenya +3
Guam +10 Kiribati**
Guatemala -6 Gilbert Islands +12
Guinea GMT Line Islands +14

Gulnea-Bissau GMT Phoenix Islands +13

Guyana -4 Korea Democratic People’s
 Republic of +9
H Hours DST Day
GMT GMT DS Korea Republic of +9
Haiti -5 Kuwait +3
Honduras -6 Kyrgyzstan +6
54
 Time Calculation

L Hours DST Day Monaco +1 +2 27 Mar - 30 Oct

GMT GMT DS
Mongolia +8
Lao People’s Montenegro +1 +2 27 Mar - 30 Oct
Democratic Republic +7
Montserrat, Leeward
Latvia +2 +3 27 Mar -30 Oct Islands +4
Lebanon 02 +3 27 Mar -30 Oct Morocco GMT +1 03 Mar - 31 Jul
Lesotho +2 Mozambique +2
Liberia GMT Myanmar +6.30
Libyan Arab Jamahiriya +2 N Hours DST Day
Liechtenstein +1 +2 27 Mar -30 Oct GMT GMT DS

Lithuania +2 +3 27 Mar - 30 Oct Namibla +1 +2 04 Sep - 01 Apr

Nauru +12
Luxembourg +1 +2 27 Mar - 30 Oct
M Hours DST Nepal +5.45
Day GMT Netherlands +1 +2 27 Mar - 30 Oct
GMT DS
New Caledonia +11
Macao (SAR) China
New Zealand **
Macedonia Former Mainland except Chatham
Yugoslav Republic of +1 +2 27 Mar - 30 Oct Island +12 +13 25 Sep - 01 Apr
Chatham Islands +12.4 +13.45 25 Sep -01Apr
Madagascar +3
Malawi +2 Nicaragua -6
Malaysia +8 Niger +1
Maldives +5 Nigeria +1
Mali GMT Niue -11
Malta +1 +2 27 Mar - 30 Oct Norfolk Island +11.30
Marshall Islands +12 Northern Mariana Islands

Martinique -4 (except Guam) +10

Mauritania GMT Norway +1 +2 27 Mar – 30 Oct
Mauritius +4 O Hours DST Day
Mayotte +3 GMT GMT DS

Mexico ** Oman +4
Mexico, Rest -6 -5 03 Mar - P Hours DST Day
30 Baja Caligornia Sur, GMT GMT DS

Chihuahua, Nayarit, Sinaloa -7 -6 03 Apr -30 Pakistan +5

OctBaja Caligornia Norte -8 -7 03 Apr - 30 Oct Palau +9
S onora -7 Panama -5
Piedras Negras, Nuevo Papua New Gulnea +10
Laredo, Reynosa, Paraguay -4 -3 02 Oct - 07 Apr
Matamoros,
Peru -5
Cludad Acuna -6 -5 13 Mar - 06
Phillppines +8
NovCludad Juarez -7 -6 13 Mar - 06
NovTijuana, Mexicall -8 -7 13 Mar - 06 Nov Pitcairn Islands -8

Micronesia Federated Oct

States Of**
Except Kosrae, Pohnpel
+10 Kosrae, Pohnpel

+11
Moldova Republic of +2 +3 27 Mar -30
Poland +1 +2 27 Mar - 30 Oct
Portugal**
Mainland and Madeira GMT +1 27 Mar
- 30 Oct Azores -1 GMT 27 Mar
- 30 Oct
Puerto Rico -4 55
 Airport Handling

Q Hours DST Day Soloman Islands +11

GMT GMT DS
Somalia +3
Qatar
South Africa +2
R Hours DST Day
Spain**
GMT GMT DS
Mainland, Balearics, Melilla,
Reunion +4 Ceuta +1 +2 27 Mar - 30 Oct
Canary Islands GMT +1 27 Mar - 30 Oct
Romania +2 +3 27 Mar - 30 Oct
Sri Lanka +5.30
Russian Federation**
Kaliningrad +2 +3 27 Mar - 30 Oct Sudan +3
Moscow, St Petersburg, Suriname -3
Astrakhan, Naryan Mar,
Izhevsk, Samara +3 +4 27 Mar - 30 Oct Swaziland +2
Perm, Nizhnevartovsk, Sweden +1 +2 27 Mar - 30 Oct
Ekaterinburg +5 +6 27 Mar - 30 Oct
Omsk, Novosibirk, Kemerovo +6 +7 27 Mar - 30 Oct Switzerland +1 +2 27 Mar - 30 Oct
Norilsk, Kyzyl +7 +8 27 Mar - 30 Oct Syrian Arab Republic +2 +3 01 Apr - 27 Oct
Bratsk, Ullan-Ude +8 +9 27 Mar - 30 Oct
T Hours DST Day
Chita, Yakutsk +9 +10 27 Mar - 30 Oct
GMT GMT DS
Khabarovsk, Vladivostok,
Yuzhno- Sakhalinsk +10 +11 27 Mar - 30 Oct Tajikistan +5
Magadan, Chukotka, Tanzania United Republic of +3
Kamchatka +11 +12 27 Mar - 30 Oct
Thailand +7
R wanda +2
Timor Leste +9
S Hours DST Day
GMT GM DS Togo GMT
T Tonga +13
Saint Barthelemy -4 Trinidad and Tobago -4
Saint Helena GMT Tunisla +1
Saint Kitts and Nevis,
Leeward Islands -4 Turkey +2 +3 28 Mar - 30 Oct
Saint Lucia -4 Turkmenistan +5

St Maarten (Dutch Part) -4 Turks and Caicos Islands -5 -4 13 Mar - 06 Nov

Tuvalu +12
Saint Martin -4 U Hours DST Day
Saint Pierre and Miquelon -3 -2 13 Mar - 06 Nov GMT GM DS
T
St Vincent and the Uganda +3
Grenadines -4 Ukralne +2 +3 27 Mar - 30 Oct
Samoa -11 United Arab Emirates +4
San Marino +1 +2 27 Mar - 30 Oct United Kindom GMT +1 27 Mar - 30 Oct
SaoMinor
United States Tome Outlying
and Principe
Islands** GMT
Saudi Arabia +3 Johnston Atoli -10
Senegal GMT Midway Island -11
Serbia +1 +2 27 Mar – 30 Oct Wake Island +12

Seychelles +4 USA**
Sierra Leone GMT Eastern Time except Indian -5 -4 13 Mar -06 Nov
Central Time -6 -5 13 Mar -06
Singapore +8 Nov Mountain Time except
S lovakia +1 +2 27 Mar - 30 Arizona -7 -6 13 Mar -06 Nov
Oct Mountain Time Zone –
Arizona -7
56 S lovenia +1 +2 27 Mar - 30
Oct
 Time Calculation

Pacific Time -8 -7 13 Mar - 06 Virgin Islands, US -4

Nov Alaska -9 -8 13 Mar - 06 Nov
Aleutian Islands -10 -9 13 Mar - 06 Nov W Hours DST
Hawalian Islands -10 Day GMT
GMT DS

Uruguay -3 -2 02 Oct - 11 Mar Wailis and Futuna Islands +12

Uzbekistan +5 Y Hours DST Day

GMT GMT DS
V Hours DST Day
GMT GMT DS Yemen +3
Vanuatu +11 Z Hours DST Day
Venezuela -4.30 GMT GMT DS
Viet Nam +7 Zambia +2

Virgin Islands, British -4 Zimbabwe +2

57