Air Traffic Services units shall be equipped with clocks indicating the time in hours, minutes and seconds, clearly visible from each operating position in the unit concerned.
This time is set using several time references in some science laboratories.
Midnight shall be designated as 2400 for the end of the day and 0000 for the beginning of the day.
The time origin is Greenwich Mean Time (GMT) which is set to the Greenwich meridian 0°.
Depending on its position in the world, a country can adopt its own hour named "standard time".
Prior to the introduction of standard time, each municipality throughout the clock-using world set its official clock, if it had one, according to the local position of the Sun.
These regions divide the world into twenty-four time zones, each one covering 15 degrees of longitude.
Problems when using standard time
For a flight which takes off at 13H00 standard time at Göteborg-Landvetter airport ESGG (Sweden) and lands at 8H00 standard time at Hong-Kong VHHH (China), if you do not know the standard time reference, it is difficult to know the exact number of hours this flight takes.
The result is certainly not 19 hours (19H = (08H – 13H) + 24H)
UTC or “Zulu” Time
Universal Time (UT) is a time standard based on the Earth's rotation.
Nearly all UTC days contain exactly 86,400 seconds.
- flight plans
- air traffic control clearances
- weather forecasts and maps
Now with the example given in the previous chapter, if you know that the flight takes off at 12H00 UTC on ESGG and lands at 24H00 UTC on VHHH, with the same reference, we are now sure that the flight takes 12Hours ( 12H = 24H – 12H)
Standard time zone
The difference between UTC time and the standard time is set by national regulation and the difference is given with a multiple of hours and sometimes one half hour is added.
The table below shows an example of offsets used to calculate the standard time in some countries:
|City (country)||standard time|
|Rio de Janeiro(Brazil)||UTC-3|
|Fernando de Noronha(Brazil)||UTC-2|
- ICAO Documentation Annex 10 - Aeronautical Telecommunications - Volume II - Communication Procedures - Chapter 3.4
- ICAO Documentation Annex 11 - Air Traffic Services - 14th Edition - July 2016 - Chapter 2.26
- VID 150259 - Creation - Wiki integration
- VID 150259 - Update September 2019
DATE OF SUBMISSION
- 12:31, 11 January 2020
- This documentation is copyrighted as part of the intellectual property of the International Virtual Aviation Organisation.
- The content of this documentation is intended for aviation simulation only and must not be used for real aviation operations.