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Suppose a domestic US civilian carrier regularly flies flight N directly from airport A to airport B, and flies back flight M from B to A.

Now, one day, the aircraft flying N is diverted to airport C, and the flight ends there (it doesn't continue to B).

Is it possible for the airline to have the aircraft fly from C to B and call that flight M? Even though that's not the route of flight M?

(By "possible" I mean "known to happen", "conceivable" rather than whether it's legal under FAA regulations, although that's interesting too.)

einpoklum
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    In my experience, flight N will be amended to A-C, and a new flight (probably also called N) will be added C-B, and then flight M will operate B-A as usual. – StephenS May 10 '21 at 18:46
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    @StephenS: That's a "standard" diversion, and it makes sense, as no passengers of N would be called upon to board at an airport they didn't expect. The question is can flight M somehow blink into existence even though nobody was expecting it. – einpoklum May 10 '21 at 20:55
  • There’s nothing stopping them from doing it that way if they wanted to; it would just be confusing to the passengers and gate agents since the flight number wouldn’t match the tickets when they reboarded at C. – StephenS May 10 '21 at 21:10
  • @StephenS: ... but you don't know of this ever happening? – einpoklum May 10 '21 at 22:06
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    DV for three things: 1.) Logical fallacy in the scenario - If the flight lands at C and ends there, not continuing to B, then it does not fly from C to B and there is no event to "rewrite". (It either flies C - B or it doesn't, pick one!) 2.) The term "rewrite" isn't defined and can be interpreted very broadly. I assume you mean assign a different flight number, but if that is what you mean why not simply say so? 3.) Asking if something is possible or conceivable is generally way too broad. (Is there a reason why renumbering a flight might be inconceivable or impossible to you?) – Michael Hall May 13 '21 at 17:49
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    ...and if your intent is to distinguish between a later continuation of the first revenue flight with the intent to get passengers to point B versus a later deadhead non-revenue flight, then the question ought to say that. Don't make us guess at what you are looking for... – Michael Hall May 13 '21 at 18:15
  • @MichaelHall: I believe you misunderstood my question. Aircraft != Flight. Flight N ends at C, then flight M starts at C. The rewriting is of the origin point for flight M. – einpoklum May 15 '21 at 08:43
  • @einpoklum, If A-B is named as event N, and B-A is named as event M, then C-B does not meet the definition of either one, and therefore should be assigned a new discrete event name in order to avoid confusion. I think I understand the basic question, I'm just baffled at how and why it's being asked. – Michael Hall May 15 '21 at 14:55
  • Perhaps you could provide more insight into your thinking by explaining the significance of the exclamation point in "Aircraft !"? Is that a typo, or a programing language symbol that gives the physical object "aircraft" some logic property that is escaping me? Because I would disagree that Aircraft=Flight. One is clearly a noun, but the other could be noun as the object of a sentence, but otherwise is a variation of the verb "fly". So, an event such as a flight is clearly different than an aircraft, although the latter is obviously required by the former... – Michael Hall May 15 '21 at 16:14
  • Aircraft + Event = Flight. I don't see this being productive or providing useful insight, but I get frustrated at miscommunication, and this superficially simple question has become a burr under my saddle as I try to understand the root of it... – Michael Hall May 16 '21 at 16:11
  • aircraft + event != flight, AFAIAC: A flight (again AFAIAC) is a sequence of scheduled flight legs, with a flight legs being an aircraft taking passengers between one airport and another. And that sequence of scheduled legs is assigned a number. – einpoklum May 16 '21 at 18:30
  • Do you not think it might be useful to define AFAIAC? Because this is just more abstraction as I see it... (in case you thought that somehow you were answering my question) – Michael Hall May 17 '21 at 00:32

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No. They've sold tickets for people to get from A to B. They've not sold tickets to anybody looking to get from C to B.

The aircraft would be ferried into position empty, then they'd operate the schedule that has been advertised & sold.

The scenario as presented doesn't really work, though... you don't get to just strand your passengers in C who bought tickets to A & tell them "sorry, good luck." Either you bus them the rest of the way, or you use AN aircraft and A crew to get them where they need to be. Whether it's the same aircraft and/or the same crew as originally planned depends on various things, but as a matter of flight numbers, you fly what you've been selling tickets for (as much of that schedule as you can) and you ferry planes & crews into position when you have to.

But rewriting things so that "flight #X now starts in C instead of A, today" doesn't happen.

Ralph J
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  • A bus might be part of the scenario, but it's not an aircraft flying those people, so it wasn't what I care about. Naturally. the airline needs to do something for the passengers. Maybe they'd go on another flight, with another number, from C to B later on. – einpoklum May 11 '21 at 08:47
  • Also - when this aircraft would be ferried, that's not considered a flown leg of a flight of that carrier, right? Just airline operational logistics, so to speak? – einpoklum May 11 '21 at 08:48
  • If a flight going to LGA (New York LaGuardia) diverted to JFK (New York Kennedy), and the weather would remain too low to get in to LGA for several hours, they could use a bus to get the pax to LGA. If the flight diverted to Boston, probably not. – Ralph J May 11 '21 at 13:26
  • Re the 2nd question ("also"): a ferry flight has its own flight number, typically outside the normal range of flight numbers that are on the published schedule. And, due to the nature of it, no tickets are sold for those. Beyond that, what it is "considered" would depend on who is doing the considering. But it isn't a passenger-carrying flight, if that helps. – Ralph J May 11 '21 at 13:31
  • It does help, because I'm looking at the US DOT's BTS on-time flight performance data, and (AFAICT) that only has passenger flights. – einpoklum May 11 '21 at 13:49
  • Ferry flights don't have a published departure/arrival time to compare their actual performance against, so yeah, the DOT stats wouldn't consider them. Ditto with maintenance check flights (FCFs), training flights, aircraft deliveries, etc. As a ticket-buying pax, I wouldn't care how marvelously on-time any of those flights were, anyway, just how well the airline meets its published schedule. – Ralph J May 11 '21 at 14:52
  • @einpoklum, so by "write" you meant write data to a file? – Michael Hall May 14 '21 at 18:32
  • @MichaelHall: No, I meant rewrite-everywhere, including in public announcements at the terminal, on websites, in its own logs, etc. – einpoklum May 14 '21 at 18:34
  • @einpoklum, Including flight plan with ATC? Because the answer varies by context, and per my critique above you need to define what you are looking for specifically. – Michael Hall May 14 '21 at 18:35
  • @MichaelHall: I want to say "no", but that's because I'm not interested in ATC flight plans. Just whatever's facing the public. – einpoklum May 14 '21 at 18:47
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Well, sort of. The continuation flight might use the original number, but the original flight must keep it unless it is cancelled.

Lets say flight 621 diverts on 25th and you send a plane to continue it, which will only get there on 26th. If flight 621 normally operates on 26th from A to B, it will have to keep the number 621, because that's what there are tickets for. The continuation flight from C can, however, also use number 621. It is departing different airport, and if it will still arrive at B well before the one scheduled for 26th, that's not a problem. See also Can an airline schedule two same-number flights to leave the same airport on the same day?. And if flight 621 isn't scheduled on 26th, well, then the number is free anyway.

That isn't rewriting the origin. It is a different flight with the same number in either case. And more likely it will get some disambiguation character, so it will be flight 621A or 2621 or such.

It is also unlikely for a domestic flight in the USA to be continued on the next day at all. There is enough air traffic that it's unlikely you wouldn't be able to get the passengers on other flights within a day if you can't get or charter a replacement aircraft for a day.

For an international flight there are such cases though. If you fly from South Africa and have to divert to Ascension Island, well, there is no other option than to send a replacement plane (that will also bring mechanics and spare parts to fix the first one) and it is likely to take a day to get it there. And it could even happen that the flight on 25th that diverted was full, but the flight on 26th is half empty and the smaller airline does not have another plane available, so it cancels the flight on 26th, rebooks the passengers from 26th on other flights and sends the plane to pick the stranded passengers from 25th, operating under the original flight number. And then they sort of rewrote the flight's origin, though it's really still rather a different flight with the same number.

Jan Hudec
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  • My question is about flights all on the same day... – einpoklum May 13 '21 at 08:28
  • @einpoklum, that would simply be continuation of the flight with a new aircraft, and there is absolutely no problem with it. It wouldn't be rewriting of origin though, just adding a stop. – Jan Hudec May 13 '21 at 13:09
  • "Simply be continuation of the flight" - that would make sense; but that's not what I asked about. I asked about when it is not a continuation of the flight, but supposedly a different flight, with a different number. – einpoklum May 13 '21 at 21:42
  • @einpoklum, If it is a completely different flight, with a flight different number, and takes off from a different airport, what possible reason might there be for "writing" some alternate "origin" on the basis of a prior leg that was never completed? What would be the rationale for doing so? I'm just having a hard time understanding what your confusion is all about... – Michael Hall May 15 '21 at 03:56
  • @MichaelHall note however that it is quite normal for one flight number to be used to a number of successive flight legs (leg = take-off to landing), including sometimes flown by different aircraft. So in that sense landing (due to emergency) and a replacement aircraft continuing with the same flight number is no different from a multi-leg flight. – Jan Hudec May 16 '21 at 20:23
  • @Jan Hudec, I understand that, but the OP specified that the second leg was NOT a continuation. (per their response to your earlier comment directly above...) – Michael Hall May 16 '21 at 21:15
  • @einpoklum, if it is to pick the passengers now stranded at C, it's a continuation. If it isn't, there is no reason for the airline to make that flight, because they didn't sell any tickets from C. – Jan Hudec May 17 '21 at 03:59
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Now, one day, the aircraft flying N is diverted to airport C, and the flight ends there (it doesn't continue to B). Is it possible for the airline to have the aircraft fly from C to B and call that flight M?

No, this is not possible. There is a flaw in the logic being presented.

There are two mutually exclusive scenarios being described here: If the aircraft flight ends at C and does NOT continue to B, then the event has terminated. There is no further flight to call “M”. The second leg doesn't exist, therefore there is no event to rename.

If the flight DOES continue on to B, then the flight could not have ended there. It is simply a continuation of the earlier flight. (You can call it M, or Q, or…) Any presumption that the flight ended at C is incorrect.

Michael Hall
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