INTERNATIONAL TIME SYSTEM

INTERNATIONAL TIME SYSTEM

As you know, the day and night are formed because of the rotation of our planet earth from west to east, facing the sun and thus the time varies in different parts of the world. The need of international reckoning of time was realized for the first time with the introduction of railways to travel across Europe during the nineteenth century. At an international governmental conference, held at Washington D.C. in 1884, the world was divided up in to 24 time zones, each measuring 15 degrees longitude wide, beginning at the prime meridian passing through Greenwich near London, Britain. Greenwich, where the first Royal Time Observatory had already been established, was set to give a common time unit to the people of the world. Thus the time observed at Greenwich is called the Greenwich Mean Time (GMT). It is also referred to as Universal Time Coordinated (UTC).

There are 12 time zones towards the east of Greenwich and twelve to the west. The time difference between two consecutive time zones is one hour. The time goes faster by an hour each time zone towards the east of Greenwich and slower the west.

The government of each country establishes a permanent official time according to its geographical size, location, convenience and politics in variation of GMT which is called the Standard Time (ST) of a country.

In many countries particularly which are located farther in the north or the south, clocks are advanced by one hour during the summer season to take the advantage of longer day light for transacting business for the purpose of convenience and saving energy. This is called the Daylight Saving Time (DST).

Each county's variation of Standard Time with GMT is expressed with either + or — sign followed by the number of hours. They are termed as the International Time Calculator. For example, Pakistan is +5 which means, Pakistan is 5 hours faster or ahead of GMT. Argentina is —3 which means, Argentina is 3 hours slower or behind GMT. An OAG extract of the International Time Calculator table is provided. in the following pages for the purpose of training. Travel consultants must have a clear concept about International Time System to provide precise information about it to the customers.

Following are examples of some aspects of its application as may be needed generally or by customers.

Conversion of GMT to Standard Time (ST):

What will be the time at Tokyo (TYO), Japan when it is 0100 hours GMT? From the table, you can find, TYO, Japan is + 9 to GMT. Therefore, 0100 GMT + 0900 = 1000 TYO i.e. the time at Tokyo will be 1000 hours What will be the time at Buenos Aires (BUE), Argentina when it is 1300 GMT? BUE, Argentina is —3 to GMT. Therefore, 1300 GMT —0300 = 1000 BUE i.e. the time at Buenos Aires will be 1000 hours Remember, to convert GMT/UTC to ST of a city/country, add the time calculator to the GMT if it has a + sign and subtract it from GMT if it bears a — sign.

Conversion of ST or DST to GMT:  What will be the GMT if the time at Singapore (SIN) is 1630 hours? SIN is + 8 to GMT which means GMT is 8 hours behind SIN. Therefore, 1630 hours SIN — 0800 = 0830 GMT What will be the GMT if the time at Honolulu (HNL), Hawaii, USA is 0815 hours?

HNL is —10 to GMT which means GMT is 10 hours ahead of HNL. Therefore, 0815 hours HNL + 1000 = 1815 GMT Remember, to convert ST of a country or a city to GMT subtract from the ST the time calculator if it has a + sign and add to it when it bears a — sign.

Time difference between two time zones:  What is the time difference between Islamabad (ISB) and Tokyo (TY0)? TY0 is + 9 and ISB is + 5 Therefore, the time difference is 9 —5 = 4 hours What is the time difference between Honolulu (HNL) and Buenos Aires (BUE)? BUE is — 3 and HNL is — 10 Therefore, the time difference is 10 —3 = 7 hours. What is the time difference between Tokyo (TYO) and Honolulu (HNL)? TYO is + 9 and HNL is — 10 Therefore, the time difference is 9 + 10 = 19 hours. Remember, to calculate the time difference between the two time zones, subtract the lower number of time calculator from the higher when the signs for both the zones are identical i.e. either — or + on the both sides. If the signs are not the same for the two zones i.e. one is — and the other + then add their time calculators.

Comparison of time between two time zones:  What will be the time at Tokyo (TYO) when it is 1200 hours at Islamabad (ISB)?, First calculate the time difference between TY0 and ISB like in the above example. The difference is 4 hours and TY0 is 4 hours ahead or faster of ISB. Therefore, add 4 hours to ISB time i.e. 1200 hours + 0400 = 1600 hours at TY0. What will be the time at Honolulu (HNL) if it is 2245 hours at Buenos Aires (BUE)? The time difference between HNL and BUE is 7 hours HNL is 7 hours behind BUE. Therefore, subtract 7 hours from BUE time i.e. 2245 hours —0700 = 1545 hours at HNL. What will be the time at Tokyo (TYO) when it is 0330 hours at Honolulu (HNL)? The time difference between TYO and HNL is 19 hours. TY0 is 19 hours ahead of HNL. Therefore add 19 hours to HNL time i.e. 0330 hours + 1900 = 2230 hours at TY0.

Total Elapsed Time on a journey;

What will be the total elapsed time on the following segment of an itinerary? SQ 438 J 27 JAN SIN DXB HK1 1935 2240 Arrival DXB 2240>>minus +0400 (time calculator UAE) =1840 GMT Departure SIN 1935>>minus +0800 (time calculator SIN) =1135 GMT  0705

Total Elapsed Time on flight SQ 438 SIN DXB is 7 hours and 5 minutes. Remember, to calculate the total elapsed time or the total time consumed on a journey convert both the arrival and departure times to the common time unit GMT/UTC. Then subtract the departure time GMT from arrival time GMT. The resultant will be the Total Elapsed Time on the flight.

International Date Line:  .

The International Date Line is an imaginary north — south line through the Pacific Ocean between the 12th time zones to west and the east. It is drawn just about on the other side of the Greenwich meridian. The time difference between those 12th time zones is 24 hours or one day (+12 to east and — 12 to west, added makes 24 hours) Thus travelling just across the International Date Line causes a difference of a day between the departure and arrival times of such flights. Travelling from west to east crossing this line a day is lost and east to west a day is gained. For example observe the following segment of an itinerary which is across the International Date Line.

NZ 008 15JAN NAN HNL HKI 1405 -2225 The hyphen sign - indicates arrival previous day in the arrival schedule of the flight which means it arrives on the 14JAN. Thus almost a day is gained travelling east to west. Now, look at the return journey HNL-NAN.

NZ 007 21JAN HNL NAN HK1 0700 #1120 The # sign with the arrival time 1120 indicates arrival after one day which means 22JAN.

Jet Lag:  

Jet lag is defined as the fatigue and other related symptoms passengers experience when travelling on a long flight crossing multiple time zones. The rapid variations in time zones during a high speed jet flight disturb the 'internal clock system' of the human body which causes jet lag. It generally, takes few days to recover from its effects mainly a slight sleep disorder.

24 hour and 12 hour clock times:  

The travel industry, particularly airlines use 24 hour clock in their time schedules of flights and operational procedures for the purpose of convenience and clear understanding of the timings. Using the flight schedules in GDS or manuals like OAG is an essential part of the job of a travel consultant. Importantly, he must have a clear concept of the International Time System so that he can clearly communicate it with the customer. Following is the comparison of 12 hour and the 24 hour clock times which need to be used a lot frequently during the transactions. According to the general concept a new day starts from the 0000 hours or 12.00 midnight. However, this particular time is not used by airlines in their time schedules to avoid confusions. Therefore, for any time at midnight they rather, use either 2359 hours or 0001 hours to be clear about the day or date.

0000 hours >>>>>12.00 midnight, 1st January

0001 hours >>>>>12.01 a.m.

0100 hours >>>» 1.00 a.m.

0200 hours >>>>> 2.00 a.m.

0300 hours >>>» 3.00 a.m

1159 hours >>>» 11.59 a.m.

1200 hours >>>>> 12.00 noon or mid day

1201 hours >>>>> 12.01 p.m.

1300 hours >>>» 1.00 p.m.

1400 hours >>>>> 2.00 p.m.

2300 hours >>>>> 11.00 p.m.

2359 hours >>>>> 11.59 p.m.

0000 hours >>>>> 12.00 midnight, 2" January

The acronyms a.m. and p.m. stand for as follows. a.m. ante meridian (before noon) p.m. post meridian (after noon)

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