The first use of 24-Hour Clock
In 1956, an American inventor made the first digital clock using 24-hour time. The 24-Hour Clock is always referred to in four (4) digits with no decimal points or mention of a.m. or p.m.There are 24 hours in a day and the 24-hour clock divides the a.m. from the p.m. at noon and midnight.
Noon is therefore represented by 1200, the 12th hour of the day, and midnight by 2400, the 24th hour of the day.
Minutes are represented by the last two (2) digits. Example: 3.55 p.m. the time on the 24-hour clock would be 1555. When it is the hour after midnight the time will only be in minutes as we have not reached 0100. Therefore, 1230 a.m. would be written as 0030.
The
only deviation from this system is at midnight. Midnight is written as 0001 or
2359 so that there is no confusion as to the day of the flight.
Here
are a few examples to show you how to convert (change) times from 12- hour
clock to 24-hour clock.
Greenwich Mean Time /Universal Co-ordinated Time
When an aircraft is in flight, it is traveling over various time zones which would create confusion with crew continually altering their watches. The ATC and Flight Scheduling also come upon the problems of local times, so in aviation, we adopt a standard time known as Greenwich Mean Time which is usually written as GMT OR Zulu.GMT
is the particular time of the day at the Greenwich Meridian and all the local
times are calculated from this. To calculate local times, it depends on how far
away from Greenwich you are and whether you are going eastwards or westwards.
24-Hour Clock Examples
Traveling west from Greenwich you do the opposite thing e.g. Los Angeles is 7 hours behind GMT 1200, local time in Los Angeles is 1200-7 which makes it 0500.
Tags
General