posted 11th June 2004 21:19
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Olendirk
POL is right - always do the math "going via Greenwich (GMT).
The following illustrative problems may help?
Depart Japan 1000 Japan Standard Time (JST) on 12 November. Flight time to Hawaii is 8 hours 40 min. What is the arrival time in Hawaii Standard Time (HST)
To indicate the date and time together, let's write the departure as 12/1000 JST
The first step is to convert your departure time to GMT. From Air Almanac STANDARD TIMES listings, to convert JST to GMT subtract 9 hours. So:
Departure time = 12/1000 JST minus 9 = 12/0100 GMT
Now add the flight time to get the arrival time in GMT:
Arrival time = 12/0100 GMT plus 8:40 = 12/0940 GMT
Lastly, convert GMT to HST which, from the Air Almanac listings, requires you to subtract 10 hours, so:
Arrival time = 12/0940 GMT minus 10:00 = 11/2340 HST
Now let's consider a flight in the opposite direction, leaving Hawaii at 2200 HST on 12 November bound for Japan with a flight time of 9 hr 30 min. What is the arrival time in Japan in JST?
Again, convert the departure time to GMT, this time by adding 10 hours:
Departure time = 12/2200 plus 10 = 12/3200 = 13/0800 GMT
Now add flight time to get the arrival time in GMT:
Arrival time = 13/0800 plus 9:30 = 13/1730 GMT
Now convert the GMT arrival time to JST by adding 9 hours:
Arrival time = 13/1730 plus 9:00 = 13/2630 = 14/0230 JST