41

Is "departure time" when the plane leaves the gate or when it takes off?

Seems like every single flight I take is delayed, but I can't tell how badly. If I have a flight that has a "departure time" of 5:20 PM, for example, and it leaves the gate at 6:30 and takes off at 6:50, is that a 1 hour and 10 minute delay or a 1 hour and 30 minute delay?

  • 2
    I assume that you're asking specifically about the passenger-facing departure times used for airline flights here, right? Different groups have different ways of measuring the start/stop times of flights for different purposes. For example, in general (i.e. non-commercial) aviation, we normally just measure engine start-up to engine shut-down time for rental hours and log time. Airlines also have different ways of measuring hours for crew pay purposes (out-in time) vs. for maintenance purposes (off-on time.) – reirab Dec 27 '17 at 6:01
  • So, while none of the Answers below are outright wrong, the reality is way more complicated than any of them suggest. The answers to your specific questions are YES, for passengers, and 1hr 10min. – Johns-305 Dec 27 '17 at 12:34
  • Why are you concerned with departure time? Travelers are almost all concerned with arrival time. Are you assuming that departure time decides arrival time? Not so. – Harper Dec 28 '17 at 2:47
  • @Harper Unless the airline notifies you of the delay before you head to the airport, late departure means you end up wasting more time sitting in the airport (or worse, in the airplane if the delay occurs after boarding). – Barmar Dec 29 '17 at 6:51
60

In general, the departure and arrival time are considered the time that the parking brake on the plane is released and applied respectively. For most major airlines, this is actually recorded automatically - the moment the brake is released the 'departure' time is recorded, and the moment it is re-applied at the destination the 'arrival' time is recorded.

On departure the parking brake is only released once the entire plane is boarded, the jetbridge/stairs have been removed, and the plane is ready to actually start taxiing (although in practice it might not actually taxi at that time due to any number of factors including other planes blocking it).

On arrival, the parking brake is set only after the plane has arrived at the gate, and before the seat-belt sign is extinguished and the jetbridge/stairs are bought to the plane, and before the door is opened.

In some cases a slightly different definition is used. For example the European Union "EU261" compensation uses the time that the aircraft door is opened as the arrival time.

So in the example given, the flight is at most 1 hour and 10 minutes delayed - although it could be less if the plane was ready to taxi before it actually started doing so.

In general, the exact length of a delay on departure is not all that relevant. What is generally seen as far more important is the arrival delay, which will frequently be significantly less than the departure delay.

  • 1
    This does not answer the question, does not address a key defect in the question, and focuses on a bunch of trivia about airline operations, none of which is relevant to the traveler. This would be a good answer if it is on aviation.se. Sorry to bust your chops, but everyone is busting my chops and it isn't fair. – Harper Dec 28 '17 at 17:46
  • 8
    @Harper you are welcome to your opinion, however the person who asked the question selected this answer - which would seem to imply they were of the belief that it did answer their question. – Doc Dec 28 '17 at 17:56
  • 2
    It clearly does answer the question, and the explanatory text can't be on aviation.se because the question wasn't. – WGroleau Jan 24 '18 at 15:03
8

There are a few times (depending on who is measuring it):

  1. The block time (airlines measure this) - this starts and ends when the plane starts and stops moving. The flight dispatcher (staff responsible for the flights departure) is the one that actually clears the plane to move. Once the parking brake is released by the cockpit, there are certain timers that start automatically in the to record the flight.

  2. The departure slot - this is the time slot given to flight from the tower. There are many airlines given the same departure slot; and they must start moving within a certain time limit of this slot, otherwise they are pushed back into the scheduling queue.

  3. The departure time - this is the time, after which, the airplane cannot be boarded. It is considered secured for takeoff. All ground people are removed, the doors are closed and armed. However as a passenger (unless you pay attention to the announcements) you may not know when this happens. Sometimes the flight senior will announce this, sometimes the pilot will announce this.

Now as far as passengers are concerned, you are really only worried about the departure time because all other times of concern are calculated based on this time.

  • It is what determines when the check-in opens.
  • It is what determines when the gate closes.
  • Delays from this time determine any compensation you may be owed. have consequences for the entire schedule; pilots and the airline's operation centers always try to "make up" any lost time here in the air (by flying faster or higher, or by changing the routing). If your departure is delayed by a margin that cannot be compensated for, this can have serious impacts across the entire schedule of that airline and indeed across many other airports.

Scheduling and on-time performance is one of the many factors that determine the cost for servicing a route. A delay is always avoided; however an early departure can also be problematic (you may not make a specific landing slot on time, or your arrival gate may not be available to you causing you to park on the apron or a longer taxi, etc. etc.)

  • 4
    Compensation is never based on the departure time. It's always based on the arrival time. – Doc Dec 27 '17 at 8:30
  • @Doc It is if your flight never departs :) – DavidPostill Dec 27 '17 at 14:37
  • 1
    @DavidPostill But then your flight never arrives, either, so for simplicity's sake you probably just keep tracking arrival time. – Nic Hartley Dec 27 '17 at 23:00
  • First this is a lot of airline technical trivia that is completely irrelevant to a traveler's question. Valuable and helpful if on aviation.se, only clutter here. You answer the question OP didn't ask, and did it well, but you did not answer the question and did overlook the fundamental defect in the question. I hate to hold a good answer to the tight standards of the forum, but the same is being done to me, and it's not fair. – Harper Dec 28 '17 at 17:51
2

Departure Time is when the flight is scheduled to leave the gate. Most importantly (to you), it's when the gate is closed and (normally) passengers may no longer board. You might sit at the gate for a while before you're cleared for pushback, depending on traffic (and other factors).

In your example (flight is scheduled for 05:20, actual pushback at 06:30, takeoff at 06:50), that flight would be delayed by 1h 10m. Note that it might be moved up in the queue for takeoff, so the delayed arrival time might be less than 1h 10m. But there are many variables.

  • 17
    That conflicts with the statement that "the gate closes 10 minutes before departure" that I sometimes see at the gate, which would seem to indicate that the gate closing time and the departure time are different. – Lemuel Gulliver Dec 27 '17 at 0:09
  • Yes, @LemuelGulliver is correct. If the flight is on-time, gate closure normally takes place before the scheduled departure time. Most airline contracts-of-carriage that I've seen require passengers to be at the departure gate at least 10 minutes before scheduled departure or else they can be considered no-show and the ticket forfeited. – reirab Dec 27 '17 at 5:56
  • 1
    I don't see a conflict. Note that there is always a time difference between gate closure (i.e. they won't allow you to board anymore) and the aircraft door closure. This difference can be as high as 20 minutes if the passengers need to take a bus to the plane. I've been in this situation quite a few times when I made it to the gate, the aircraft was still parked but they closed the gate and wouldn't let me board. – George Y. Dec 27 '17 at 5:58
  • @GeorgeY. This answer says that the departure time is "when the gate is closed and (normally) passengers may no longer board." That's incorrect (at least on every airline I can ever recall flying.) The gate typically closes 10 minutes or more prior to the scheduled departure time and a passenger arriving after that time can be denied boarding according to the contract of carriage. – reirab Dec 27 '17 at 6:06
  • @reirab I see "Departure Time is when the flight is scheduled to leave the gate" which is correct. The second part contradicts the first though. – George Y. Dec 27 '17 at 6:10
2

Not directly an answer to your question, but when you speak about flight delays, the departure time is not what actually matters. What matters is the arrival time. And at least in the EU, that has a definite, legal answer: The plane counts as arrived when the doors open.

I see some answers and comments here that get this part wrong, which I why I'm posting this answer. Maybe the US is different, though.

Source: https://www.bottonline.co.uk/flight-delay-compensation/claim-guides/definition-of-arrival-time

  • This is not an answer to the question. No seriously, I can't downvote this because it's correct (and ripped right from my answer which did get downvoted.). This forum is ridiculously unfair. – Harper Dec 28 '17 at 17:56
  • 1
    SMH some people will downvote anything. +1 to counteract. – Harper Dec 28 '17 at 21:09
0

1:10, but that's not the end of the tale. Airplanes can make up time and post an improved arrival time... but not so likely in your case. Regardless, it's not over til it's over.

I have seen airlines intentionally pad the schedule: an uneventful on-time departure usually results in an early arrival IME, and even a slightly late departure can result in an on-time arrival. That is one advantage of air flights, which are scheduled by segment; trains can't pad except at the final destination - and they can't leave a station earlier than carded.

A late departure may be for connecting passengers whose plane is itself late, and for whom the alternative would be an overnight stay, ruined plans, and great expense and trouble for the airline too.

Now if you want to know more about the flight aspects of this, you could re-ask this question over on aviation stack exchange.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.