There's a daily flight, let's call it AB 1234 which leaves at 11am with a flight duration of more than 13 hours. I noticed that every day, the same flight AB 1234 leaves at 11am. It seems physically impossible for the same plane to travel 13 hours and return in about a similar amount of time to still make the next day flight.

Is it possible for two or more different planes to share the same flight number?

  • I had a similar experience with a Southwest flight. Example: Flight 800 arriving in Phoenix at 2:10PM and Flight 800 departing Phoenix at 1:37PM...doesn't sound legal nor does it make sense if something should happen to one of the aircraft during that 33 minute time frame!! Shame on the airline for such confusion.
    – user36877
    Nov 5, 2015 at 12:17
  • 1
    The inbound and outbound flights nearly always use different flight numbers. For example the outbound would be XX001, however the return flight would be XX002. This reduces the chance of confusion, however if the flight is heavily delayed, it may clash with the following days flight. However this is not an issue, as airlines and ATC use "callsigns" rather than flight numbers, which can easily be changed if a clash is going to occur. See my answer for more info. Nov 5, 2015 at 14:08

4 Answers 4


A flight number is simply that: a number for a flight, not a number for a plane.

The planes are just an implementation detail to make flights happen.

  • This may be on the right track, but it seems that it doesn't actually answer the question. Feb 16, 2022 at 15:11

I think you are confusing aircraft tail number with flight number - the former is a unique registration number for each plane, while the latter simply describes a unique route operated. When airlines operate flights on a codeshare basis, one physical aircraft could be flying the same physical route sold under different flight numbers too!


Some flights don't even use the same plane type every day. Sometimes flight numbers are used for different destinations on different days. Here's a current example on Flightaware.com: United 831. For four recent days, the flight operated from Washington Dulles to Cancun. Then for the following three days, the flight operated from New Orleans to Denver. That pattern repeats. On most days, the flight is on an Airbus A320 (for both of the unique itineraries), but on January 19, the equipment is listed as a Boeing 757-200.

  • Yeah, I've seen the different plane types based on day several times in situations where a route has significantly more demand on some days than others. I remember seeing on a Cathay Pacific route from Hong Kong -> Cebu -> Hong Kong that the equipment could be an A330, A340, 777, or 747 depending on day of the week.
    – reirab
    Sep 18, 2014 at 13:39
  • @reirab or just availability. I've seen BA 747s at Amsterdam to replace a broken down 757 or A320 (which are/were the normal material for the route). It was just the one that could be made available quickest to minimise delays. Of course that particular flight isn't then going to turn a profit for the airline...
    – jwenting
    Oct 6, 2014 at 8:46
  • @jwenting That's true, also, though I was referring to the scheduled aircraft actually varying by day of the week in the HKG->CEB instance I was referring to. I've run into what you mentioned also, though, where DL used a 767 to replace a broken down 757, presumably because they had a spare 767 sitting around at ATL that could be made available more quickly than getting another 757.
    – reirab
    Oct 13, 2014 at 4:18

Yes, the same flight number can be used to refer to multiple flights active at the same time. This happens fairly regularly if a flight is heavily delayed. The previous days flight may still be active the same time as the current days flight takes off.

"Direct" Flights

It is also fairly common that the same flight number is used to refer to more than one route - this is fairly common in the US.

When Continental first launched service to Edinburgh, the flight operated under the flight code of CO37, which operated Edinburgh-Newark. There was also a second flight, Newark to Orlando, which also used the flight number CO37. This was operated as a "direct" flight, and both destinations (Newark and Orlando) were advertised as being served from Edinburgh.

In some circumstances, if the Edinburgh flight was delayed by a few hours, then it could be landing into Newark as the Orlando flight departs.


This doesn't pose a problem, as flight numbers are only used by travel agencies and passengers.

In aviation, the airlines and air traffic control system instead rely on callsigns. These callsigns are often the same* as the flight number - Continental used the callsign Continental 37 for the Edinburgh flight. However, callsigns can be changed at very short notice, so if the Edinburgh flight was indeed running late, the Orlando flight would operate under a different flight code to avoid any confusion. This may be as simple as adding "B" to the callsign, to become Continental 37B.

*Conventions for selecting callsigns are airline dependent. British Airways and Easyjet, for example, use callsigns that have no relation to the flight number, while other airlines tend to mirror the flight number in the call sign.

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