Last month I booked a flight on American Airlines for the end of December. Today I got an email from them stating that there had been a change in my trip, and here are the updated details of my flights.

For both flights (IAD->LAX and LAX->SYD), the only change I can see is that the departure and arrival times have changed slightly (<30 minutes). The aircraft did not change either, but both flights are now longer! The first flight gained 49 minutes and the second flight gained 10 minutes.

10 minutes on a 15 hour flight is negligible, but adding almost an hour to what was a 5.5 hour flight seems like quite a lot! Why would an airline change their flight time so drastically, when seemingly nothing but the departure time has changed?

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    This would probably have been better on our Aviation site Commented Sep 18, 2018 at 13:17
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    Can you provide the exact date and the schedules before/after? If it's on a very busy day (say, the week-end before or after Christmas), they could have added some buffer to take congestion into account. It may not make the actual flight longer, just make sure you arrive "on time" even if you leave late. They should have taken that into account earlier, but you never know... It could also be they received notification of an event that could disrupt things at specific times (say, the President using the same airport as you). Hard to guess.
    – jcaron
    Commented Sep 18, 2018 at 13:41
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    Also, Airlines have started to extend 'planned' flying times, so they are not so often reported as being late.
    – Aganju
    Commented Sep 18, 2018 at 15:26
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    @Aganju: Or, being less cynical: advances in data collection and data mining allow the airlines to predict actual times better than before. Commented Sep 18, 2018 at 15:46

4 Answers 4


The two most likely causes are a change in routing or a change in take off and landing slots.

Routes can change for various reasons, some may be longer or shorter. They usually don't make that much of a difference to a short flight (although it can happen if one route had a better jetstream, those are usually variable)

Most likely is a rearrangement of logistics meaning take off or landing slots have changed meaning the aircraft needs to take less or more time to get to its slot. These may be changed due for seasonal reasons, or because an airport rearranges to accommodate new bids for the most desirable time slots etc.


For any particular flight, you could look it up in FlightAware and see if there’s an annotation for the change. Most probably not. For any particular flight, Rory’s answer is likely correct - that it’s a gate scheduling issue.

However, there’s a general trend in the aviation industry to post longer flight times for the same routes than previously:

  1. Airlines are flying airplanes slower to save fuel. Back when there was competition and we used travel agents, the fastest flights would show first in SABRE and other databases but as airlines monopolize routes and people sort by price and not time, there’s no reason not to slow down to save fuel.

  2. Congestion at airports, cuts to maintenance, number of standby planes and crew, and other operational issue means they need to build in more buffer time for an ontime arrival. No one likes to arrive late while arriving early seems a crowd pleaser.


Airlines sometimes make a push to improve their on-time statistics, and this usually includes publishing longer flight times, which will automatically improve the on-time performance for any flight not already running at 100%.

  • While padding schedules is an old trick, it isn't likely that AA would do this for IAD-LAX specifically, as neither those flights nor those airports are prone to significant delays. For an adjustment in Northern Hemisphere summer, it might be more plausible, since LA gets fog and DC gets thunderstorms.
    – choster
    Commented Sep 19, 2018 at 21:24

The accepted answer is incorrect. We have slot controls at only a few U.S. airports, and neither LAX nor IAD is one.

The answer is that airlines adjust schedules all the time. That's a big increase but not unprecedented. There are so many interconnected factors at play that it's nearly impossible to get a neat answer.

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    I'd like to upvote this if it's correct and the accepted answer is incorrect. However, I'd need some sources for the claims as I have no idea who is right or wrong.
    – Martin
    Commented Sep 21, 2018 at 9:47

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