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Guest lmoelleb

International Date Line

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I am putting the finishing touches on a few flight plans, FedEx, Northwest Cargo and a vintage Northwest Airlines schedule from 1949. I will soon be doing a UPS schedule. They all have flights that cross the International Date Line on the Pacific routes.Do I need to reflect this fact when I enter takeoff and arrival times and dates?Northwest flight 69 and 70 as an example:Takeoff: DTW 1230 L SundayArrive: RJBB 1525 L Monday (flight adds a day)Takeoff: RJBB 1645 L MondayArrive: RCTP 1815 L MondayTakeoff: RCTP 1130 L TuesdayArrive: RJBB 1505 L TuesdayTakeoff: RJBB 1635 L TuesdayArrive: DTW 1530 L Monday (flight subtracts a day)If I make a weekly schedule reflecting these date changes, will the plane operate the way I want, or will it get "confused" and sit on the ground for a week waiting for the "correct" departure day?Appreciate any insight you may have.Check Six!!!!!Rick

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From my point of view you don't have to do anything special for your purpose.All dep. times are in GMT - not in local time. While the local time of course will jumpt dates, GMT just continues running and is the same everywhere in the world.E.g. A flight from Hong Kong to Los Angeles departs noon local time at VHHH. VHHH is 8 hours ahead of GMT I believe. So the flight would depart 1200 - 0800 = 0400 GMT. The flight takes some 13 hours, so it arrive in KLAX 0400 + 1300 = 1700 GMT. KLAX is 8 hours behind GMT, so the local time would be 1700 + 0800 = 0100. After a 3 hour turn around time it would fly back to Hong Kong: Departure = 1700 GMT + 0300 = 2000 GMT (0400 local time). Flight time no probably 14 hours, so the flight would arrive 2000 + 1400 = 1000 GMT (or 1000 + 0800 = 1800 local time)It sounds confusing, but if you only look at the GMT times it's simple, in the example departure and arrival would be on the same day (GMT day that is!).so the plan could look like ... 0/04:00:00,0/17:00:00,...,KLAX,... 0/20:00:00,1/10:00:00,...,VHHH,I hope I confused you completely ;-)Frank

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Thanks for your response.Although the Zulu time will remain the same all over the world, at the International Date Line (even though you are only one hour different from your neighbor) you are actually on a different day. (A day ahead traveling west, and a day behind traveling east). This peculiarity only exists at the Date line.So you are correct, Zulu time remains contant, but the DATE changes. That is the dilema I asked about when making flight plans.Check Six !!!!!Rick

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I might be wrong so correct me if necessary. The last leg of your flight:departure RJBB at 1635 RJBB (0735 GMT) (0135 KDFW)arrival KDFW at 1530 KDFW (2130 GMT) (0630 RJBB)The flight would arrive arrive on the same day, not one day earlier.Looking at it from the 'local' point of view, one could say that you arrive one hour before departure even though the flight is 14 hours ;-)However your first leg was right:departure KDFW at 1230 KDFW (1830 GMT) (0330 RJBB)arrival RJBB at 1525 RJBB (0625 GMT) (0025 KDFW)Departure is around noon, while arrival is in the afternoon of the next day! But GMT reflects that too.Maybe I am confused now ;-) However, I think even FS2002 has terrible problems with the time zones - LOL. Many times my arrival time was totally wrong - even without crossing the date line :-)Cheers!Frank

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The "day difference" is due to local (repeat local) time being offset by -12 hours on one side of the line, and +12 hours on the other (ok, it's probably +/- 11 or something close to that in reality as +12 would apply to the line only, and no one cares to make a timezone for a line). :)When using GMT this does not happen as there is no time difference between the two sides of the date line - the entire world changes GMT date at 00:00Z (and 24:00Z of couse, but the change at 24:00Z is the same as the one at 00:00Z the following day which has no importance to this what-so-ever, but I thought I would throw in the extra information to confuse the few people still awake).

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I know this is probably getting a little tedious. But I would refer you to a couple of web sites that may explain things a little better than I have: http://aa.usno.navy.mil/faq/docs/international_date.htmland http://scienceworld.wolfram.com/astronomy/...alDateLine.htmlAnd an exerpt from an other site explains the travelers paradox:Why must we have a Date Line?The problem is simply this: time around the world is divided into zones, so that in theory noon in each country coincides approximately with when the sun is overhead (or at its highest). The only other alternative would be to have the whole world on the same time which would create even more problems.Imagine this: Suppose a traveler started off around the world, wearing a wristwatch. Every time he got to the next time zone, he would advance his watch by one hour to show local time. When he got to midnight he would advance the date on his watch by one day. This is fine, and all is well until he gets all the way back to his starting point. Then he would find to his amazement, when he checked his watch, that the time was correct, but the date indicated a day later than his friend's who had stayed at home the whole time. If he traveled around the world in the opposite direction, he would set his watch back one hour each zone, and would eventually find that his watch showed a day too early, when compared with his friend - he would arrive home before he left!The International Date Line was set up to counteract this problem, and works like this: in the above situation, at some point on his journey around the world, the traveler would cross over the International Date Line, and would thus set his watch back one day to compensate. Then, when he arrived home everything would be in order. Traveling in the reverse direction he would set his watch date forward one day when he crossed the line. Again all would be in order upon his return. Even though local time is one hour different, when you pass over the date line, no matter what time of day it is locally, you change days!Check Six !!!!!Rick

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I have done several flights that cross the date line, and they all show up on the day I specify, on either side of the line.Hope this helps,-- Tom GibsonCalifornia Classic Propliners: http://www.calclassic.com/Cal Classic Alco Page: http://www.calclassic.com/alco/Freeflight Design Shop: http://www.freeflightdesign.com/ San Diego Model RR Museum: http://www.sdmodelrailroadm.com/Drop by! ___x_x_(")_x_x___

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Thanks for the links - very nicely explained indeed ;-)Anyway, the last leg of your suggested route would still arrive on a Tuesday and not on a Monday. ----- 8< ----- 8< ----- 8< ----- 8< ----- 8< Takeoff: RJBB 1635 L TuesdayArrive: DTW 1530 L Monday (flight subtracts a day)----- 8< ----- 8< ----- 8< ----- 8< ----- 8< I try to explain why ;-)The trip starts in the afternoon in Japan and it leads to the East. On your trip it will become darker and darker and at one point the local time will reach midnight (00:00)and hence your calendar would advance by one day to Wednesday.At another point of the trip you would pass the date line and you would have to subtract one day from your date, so it would be Tuesday again.Hence you will arrive a Tuesday and not on a Monday...Can it become any more confusing? LOLCheers!Frank

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