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Say an example flight FRA-LHR, was scheduled say 9am every day. Now will that flight be then moved to 10am once the change to DST happens or will it remain at 9am?

I would expect the flight times schedule to remain the same i.e. the daily morning FRA to LHR flight will be always departing at 9am (independent of summer/winter time changes). My knowledge in this area is limited so I wanted to know what the experts on this site say.

My question is more directed at the flight schedules i.e. the daily flight scheduled at 9am for example - does it undergo schedule change and is moved to 8am/10am or is this time fixed (underlying assumption being: in general a flight is scheduled for a certain time to meet a demand, so moving the local time is not necessarily feasible).

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  • $\begingroup$ Your intuition is correct, airline schedules (nor virtually any other) are not set by the sun. I've had many appointments at 12pm local time, but never an appointment at local solar noon. $\endgroup$ – Nuclear Wang Jul 17 '17 at 17:25
  • $\begingroup$ The more interesting situation is when a flight operates between a country which uses daylight savings time and another country which doesn't. Or when the two countries switch over on different dates (i.e. USA and Mexico switch on dates that are a week or three apart). $\endgroup$ – Ralph J Jan 24 at 20:41
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As others have pointed out, in cases where both origin and destination shift to DST, there likely isn't a change.

When only one end of the flight shifts to DST it does have an effect on aircraft scheduling, so it will likely result in a schedule adjustment. A good example can be seen on Delta's daily flights between Detroit and Shanghai. China does not observe DST, so Shanghai is 13 hours ahead of Detroit EST and only 12 hours ahead of Detroit EDT.

In the summer with Detroit in EDT, the schedule is:

DTW - PVG Flight 583 Dep: 4:39 pm arr: 6:55 pm
PVG - DTW Flight 582 Dep: 11:45 am arr: 1:48 pm

and in the winter with Detroit in EST, the schedule is:

DTW - PVG Flight 583 Dep: 3:30 pm arr: 7:20 pm
PVG - DTW Flight 582 Dep: 12:20 pm arr: 1:16 pm

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  • $\begingroup$ Very interesting since neither shift is 1 hour in an attempt to keep at least one end anchored. They have shifts in scheduled times at both departure and arrival. Weird... $\endgroup$ – FreeMan Jul 18 '17 at 13:03
  • $\begingroup$ Also, the flights take longer in the winter than the summer. I guess that's gate-to-gate time, so they allow an extra hour for de-icing and other delays in the winter? $\endgroup$ – FreeMan Jul 18 '17 at 13:09
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    $\begingroup$ Remember that these long overseas flights often affect other scheduled flights that are connectors so there is a ripple effect through the schedule. And wind patterns shift between winter and summer. $\endgroup$ – Gerry Jul 18 '17 at 13:14
  • $\begingroup$ thank you FreeMan & Gerry for you answers - appreciate the help. Just to share with you some of my understanding - a somewhat random time schedule change effect can be observed in EU market as well - which aligns with Gerry's arguments. Random in the sense that some flights move forward 30mins some 50mins etc. $\endgroup$ – davidski Jul 19 '17 at 14:02
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It will affect scheduled flight times the same way it will affect your favorite TV show's air time.

i.e. it won't*

It will affect apparent flight duration if the departure and arrival airports switch to DST on different days of the year, but actual time in the air will remain the same.

* The caveat for that is if you happen to be in an area that A) does not switch to DST and B) your favorite TV show happens to be broadcast from an area that does switch to DST. (This situation happened every year in Indiana for many years until IN joined the 19th** century and switched to DST in the summer.)

** Yes I know that DST was a 20th century invention, it's just that Indiana is a bit behind the times...

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    $\begingroup$ @mins some states don't want DST because they're afraid the curtains will fade from the extra hour of daylight. $\endgroup$ – Koyovis Jul 17 '17 at 22:14
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    $\begingroup$ Round here, the general excuse was "the cows won't know when to give milk". $\endgroup$ – FreeMan Jul 17 '17 at 23:34
  • $\begingroup$ thanks for the answer @FreeMan and sorry i probably did not make myself clear. I am aware that actual time in the air is the same, however my question was more directed at the flight schedules i.e. the daily flight scheduled at 9am for example - does it undergo schedule change and is moved to 8am/10am or is this time fixed (underlying assumption being : in general a flight is scheduled for a certain time to meet a demand, so moving the local time is not necessarily feasible) $\endgroup$ – davidski Jul 18 '17 at 10:06
  • $\begingroup$ judging by your answer this is indeed the case $\endgroup$ – davidski Jul 18 '17 at 10:07
  • $\begingroup$ i am interested if anyone else has a different point / counter point in the answers $\endgroup$ – davidski Jul 18 '17 at 10:10

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