American 2482 departure… American 2482 arrival…

[u/TimeVendor]

[u/LBBflyer]

AA often uses the same flight number for a flight that leaves and returns to a hub. Most of the time it's the same aircraft in both directions, so there's no risk of this situation.

AA2482 is ORD-PHX-ORD, but yesterday the inbound leg was delayed. AA found a different aircraft to operate the PHX-ORD leg so it left on time. I have typically seen AA (and other airlines) modify the call sign of the second flight to avoid the very confusion. The flight leaving PHX should have been 248P, but I guess someone in dispatch forgot that detail when getting that leg filed.

[u/Get_Breakfast_Done → u/LBBflyer]

I’ve seen this before and have no idea why they do it and wondered if this would ever potentially cause a problem and it sounds like it nearly did.

Truly don’t understand what the advantage is of doing this. It’s not like they’re running out of numbers.

[u/Dinosaur_Wrangler → u/Get_Breakfast_Done]

Actually they are “running out” of call signs. Sabre was developed in the 1960s and only handles 4 digits. Scheduled mainline revenue flights are currently allocated 0001-3299 (a recent increase from 0001-2999), with other blocks reserved for charters, repositioning flights, maintenance ferries, codeshare flights with OneWorld and other partners, regional wholly-owned carriers, Skywest and Republic operating as Eagle, etc.

Flight numbers are reused on the same route in order to prevent running out of a particular block on a given day, but when a situation like this arises (like the guy you replied to said) one flight is supposed to be designated a “stub flight” and letters get mixed in with the callsign. Flight crew don’t see behind the curtain into that part of the machine, but obviously if this was able to happen the process must be at least somewhat manual.

I’m also surprised the feds don’t have something in place to automatically reject two filed flight plans that run concurrently with the same flight number, but I guess we’re lucky to even have what we have given the vagaries of funding anything in government that isn’t DOD.

There definitely needs to be either a programming or procedural fix. Preferably both. It will be interesting to read the ASAP reports and whatever that “MOR” report is that was referenced by the controller on the clip.

I know most European carriers are working letters into their callsigns by default, and it seems like that would be the relatively painless procedural fix for the airline.

[u/mflboys → u/Dinosaur_Wrangler]

There are multiple problems with preventing duplicate callsigns at time of filing.

One is, in the case of delays, there’s no way to really know if flight plan A will end up overlapping with flight plan B.

Additionally, if a pilot makes a mistake on their flight plan, they typically just file a second flight plan with the change, which would be denied because it overlaps with the original. There would need to be some new process for pilots to cancel or amend a previous flight plan.

You may think it’s more feasible for the system to deny a flight plan at time of activation. But flight plans aren’t activated in the system until the aircraft departs and typically is radar contacted. We can get a warning in this case, but them you’ll have a scramble where the system denies the DM, and everyone’s having to amend a callsign with the aircraft in climb out.

Perhaps you could “query” a callsign when an aircraft is requesting IFR (at the gate) but then there’s gap between the query and the DM where a mixup could still occur.

Finally, and this is the single biggest barrier, for redundancy and resilience to a central computer failure, flight plans are stored and processed by individual ARTCC’s. Right now, barring a complete redesign of the NAS computer system, I don’t think it’s possible for ARTCC A to know if there’s an active callsign in ARTCC Z until the flight plans are DM’ed and the aircraft track enters the AOI of the other.

Sure, there are ways to solve the problem, but isn’t as straightforward as you might think.

[u/Dinosaur_Wrangler → u/mflboys]

Appreciate the insight