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I stay in Pittsburgh, the time zone is EDT (Eastern Daylight Time). I purchased a ticket of a flight that departs at 8.20 AM from here on next Thursday. When I purchased this, there was a different time in Pittsburgh -- and few days before it 'sprang forward' by 1 hour -- the standard thing that happens for daylight savings times. My question is: does the time shown on my ticket take care of this change, and I don't need to recalculate the departure time, just show up according to the current time at Pittsburgh? My guess is 'yes', just want to double check from experienced travellers -- don't want to miss my flight.

Update after the travel: Yes, indeed it takes care of that. So, the travellers can be calculation-free :-)

Pagol
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  • With the advent of computers calculating DST time became a mere triviality, so I wouldn't worry. – JonathanReez Mar 20 '16 at 21:56
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    A more interesting question would be what happens for flights that depart between 1-2am on the day in November when DST ends, because there are actually two 1-2am periods that day in the local time. – user102008 Mar 21 '16 at 04:19
  • @user102008 That's this question. Generally, very few flights are leaving after 1am anyway. – Zach Lipton Mar 21 '16 at 05:49
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    @JonathanReez trivial unless they change the rules at short notice: https://blogs.technet.microsoft.com/dst2007/2008/05/26/advisory-changes-to-daylight-saving-time-in-morocco-and-pakistan-on-june-1-2008/ which did lead to a round of flight schedule changes – Flexo Mar 21 '16 at 06:58
  • My flight itinerary which includes a flight entirely within Arizona with a small airline, departing shortly after DST starts everywhere else, was inexplicably shifted by an hour months after booking. The shift exactly matches the offset due to Arizona not using DST. I wonder if there was a bug somewhere in DST/non-DST calculations. – gerrit Mar 21 '16 at 10:56
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    @Jonathan There is absolutely nothing trivial about datetime, certainly not for computers. Just one fun example: At what time (UTC) would my flight leave from the airport in Vienna, if it was scheduled to take-off at 2:30am local time on October 30th this year? – Voo Mar 21 '16 at 12:46
  • @Voo there's pretty much only 60 minutes on the whole year when there could be confusion, yes – JonathanReez Mar 21 '16 at 13:22
  • @Voo Normally, date/time values are computed and stored in UTC where DST doesn't matter. Most programs just convert them to local time on the fly for display purposes, but leave the internal representation in UTC. That said, you're right that time zone code can get ugly, especially where DST is involved (and in figuring out where and when DST happens.) – reirab Mar 21 '16 at 14:20
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    @Jonathan Yup only then. Well there might have been some complications say for people at the end of December 2011 in Samoa, but apart from that.. (do I have to go on?). My point being if you think that anything with datetimes is trivial you just don't know enough. – Voo Mar 21 '16 at 14:47
  • @reirab No problem with UTC but the time on the ticket is in local time, so that ends up with an ambiguity by design which can't be avoided. I guess they just make sure there are no passenger flights leaving around that time, which should be easy enough, what with it being 3am. With all those datetime curiosities due to political process (it was Israel that voted on when DST is in effect each year, right?), I wouldn't be surprised if there haven't been lots of problems in the past though. – Voo Mar 21 '16 at 14:50
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    @Voo interestingly enough, there were plenty of flights out of JFK on November 1st, 2015 between 1 and 2 AM (previous DST date): http://i.imgur.com/L9bTUUp.png – JonathanReez Mar 21 '16 at 16:06
  • @Jonathan Really cool find. I'm wondering how they avoided the confusion among passengers? – Voo Mar 21 '16 at 16:34
  • @Voo see related question: http://travel.stackexchange.com/questions/65499/when-a-flights-departs-in-the-middle-of-the-winter-daylight-saving-time-switch?noredirect=1#comment137597_65499 – JonathanReez Mar 21 '16 at 16:47
  • At least the airlines are reasonably sane. When I worked for the Dutch railroads, their DST procedure was to physically stop all trains and restart all computers. :\ – MSalters Mar 22 '16 at 09:34
  • @MSalters To be fair I'm sure that if airlines could do the same thing during flight they would ;) – Voo Mar 22 '16 at 17:23
  • A real travel-related problem: Traveller returns home, pays at the car park two minutes before 2am, leaves 5 minutes later - and by the time he's leaving, it's three minutes past 3am and they don't want to let him out. Also read of a guy who got his pizza delivered 30 minutes before he ordered it... – gnasher729 Dec 08 '16 at 08:48

2 Answers2

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Yes, flight departure times for normal passenger flights are always shown in official local time, which follows DST changes according to the local rules.

Greg Hewgill
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  • I was recently on a train that was delayed due to work on the track and the times on the ticket (sold and printed months in advance) did match those of the actual journey (not those of the usual one.) Departure times in daylight saving is childs play compared to that. – Willeke Mar 20 '16 at 22:00
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    I wonder when a flight scheduled to leave Pittsburgh at 1:30 AM, November 6 actually leaves. Maybe it just takes off, goes into a holding pattern for an hour, comes back and tries again. – Jason C Mar 21 '16 at 00:35
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    @JasonC lol :-P but seriously though, I think it's a moot point unless there actually is a flight that takes off at that time. Air traffic is pretty light after midnight and it wouldn't surprise me if they just don't schedule flights during the repeated hour, to avoid confusion. ninja edit after reading comments on the question: https://travel.stackexchange.com/questions/10419/problems-with-certain-times-occuring-twice-or-not-at-all-on-night-of-daylight?rq=1 – David Z Mar 21 '16 at 07:05
  • @JasonC That said, I actually was looking at flights that landed between 1 and 2 am on the day DST ended. I didn't even think about that time being ambiguous until later. Fortunately, I scheduled a different time anyway, so it ended up being moot. – reirab Mar 21 '16 at 14:16
  • @DavidZ FWIW I had a delayed flight land around 1:30 at Pittsburgh a few years ago, the only people I saw there were other passengers on my flight and airport staff (mostly the cleaning crew). – Dan Is Fiddling By Firelight Mar 21 '16 at 15:18
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    @JasonC: Ideally it will say "1:30AM EST" or "1:30AM EDT" which will let you know exactly when it leaves. – Dietrich Epp Mar 21 '16 at 20:58
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The time shown on the ticket is, as far as I know, always local time as it will apply when the flight departs. In particular, I wouldn't expect a ticket to be sold with a time quoted in EST for flight on a day on which daylight saving time was in force. The change in time of your ticket was probably for the airline's operational reasons and the start of daylight saving was almost certainly a coincidence.

However, in any case where you're uncertain about this, you should check with your airline, not ask random people on the internet to guess for you.

David Richerby
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