Two American Airlines jets with exactly the same callsign ended up on the same air traffic control frequency, basically flying toward one another. This is very odd, and one wonders how exactly this happened (thanks to Hans for flagging this).
In this post:
American flight AA2482 double trouble in Phoenix
Every flight has a callsign that’s used with air traffic control, and for commercial aircraft, that’s generally going to be the generic airline callsign plus the flight number. Callsigns are of course unique to a particular flight, because that’s the way that air traffic control communicates with pilots.
That brings us to what happened very late last night (Thursday, August 13, 2026), in Phoenix. AA2482 is a flight number used by American between Chicago (ORD) and Phoenix (PHX). The flight number is actually used in both directions of travel, which isn’t that uncommon, with both flights being operated by Boeing 737-800s.
However, things got a little strange last night, because it’s not necessarily the same plane that flies in both directions (since American has many 737s in Phoenix that it can swap around). Last night:
- AA2482 from Chicago to Phoenix landed at 12:13AM, well behind the scheduled 10:43PM arrival
- AA2482 from Phoenix to Chicago took off at 11:58PM, roughly on-time, given its scheduled 11:45PM departure
What happened is that both planes ended up on the same Phoenix air traffic control frequency at the same time, with the same callsign. You can see the visualization of that below, along with the air traffic control audio.
As you can hear, the air traffic controller says “I’ve been working air traffic for 25 years, I’ve never seen two aircraft pretty much merge with the same callsign, that’s pretty incredible.”
He handled this like a champ, making it clear to pilots of both planes that there was another plane with the same callsign on the frequency. He was great about speaking clearly, and clarifying “American 2482 on the arrival” vs. “American 2482 on the departure.” The pilots of both planes also deserve credit, because they were (understandably) paying extra close attention.
How did this American callsign situation get messed up?
As I mentioned above, on the surface, it’s not unusual to see the same callsign used for multiple flights, and in theory, it’s possible the two planes are in the air at the same time. However, in situations where that’s the case, what typically happens is that one of the planes takes on a different callsign, even if it’s something as simple as adding a letter to the end of the flight number, “like American 2482 bravo,” or something.
One thing I’m not sure of is who would typically be responsible for ensuring that? Is that something that a company’s operations department is supposed to take care of, does air traffic control somehow do that, or something else? In other words, who wasn’t doing their job here?
This is definitely unusual, though, as it’s kind of wild how the two planes ended up on the same frequency, basically heading for one another. What are the odds of that?
Bottom line
Two American Airlines planes ended up on the same air traffic control frequency with the same callsign, basically heading straight for one another. Ultimately the flight number is used for both directions of travel between Chicago and Phoenix, but in this case, the Chicago to Phoenix flight was delayed, while the return flight operated on time, obviously with a different aircraft.
I think the air traffic controller said it best — in his 25 years on the job, that’s the first time he saw something like that.
What do you make of this odd air traffic control situation?
Nothing going on, nothing to see here. Isn't it strange how many close calls there are this year alone?
So it appears that in summary:
- old system assumptions limit the length of flight numbers
- in the USA, which has the highest density of flights and so hit the issue first, nobody insisted on solving it by extending field-length, and confusing/dangerous duplication is accepted
- outside the USA, workarounds have been found to avoid confusion/danger, and are enforced by convention.
Why does the Radar System allow the same callsign for two different squawks? One of the many deficiencies in the US ATC System.
Normally the the flight numbers are given odd or even for the flights on a route. Why AA is not working like this?
That's not a thing. You might be thinking about the cruising altitude assignments, which are set to odd or even based on East or West compass headings. East is odd altitudes, West is even.
I blame the perils of the dreaded midnight shift, both in AA’s IOC and in the PHX Tracon. You can have tired, junior dispatchers and tired, overworked controllers, trying to stay awake and alert while working combined positions.
You've got to love the attitude of some. Read the article, think I have the solution---never use the same numbers for different flights, and post it. Nevermind that dozens have posted the same idea and in-the-know readers have responded why it is necessary under the current system to reuse on large airlines. Geesh, it like teaching a class and getting the same question fourteen times because nobody listens to others' questions or their answers.
The problem only exists if an airline is very large and also funnels everything through the same hub. Anyone else could allocate the same flight number to routes that do not overlap.
I have never come across the practice of the same flight number applying to both inbound and outbound (triangular routes and/or fifth-freedom arrangements obviously don't fall into that category) so I'm surprised by the claim it's not unusual.
Does anyone have any links to IATA/ICAO guidance around the issue, or any examples of this practice being deployed by any airline that's not based in the US or Canada?
Well, the exact same thing could have happened with a continuing route. Not sure why everyone keeps bringing up the point it was the same flight number inbound and outbound
"Stubbing flights" (altering 1 of the 2 call signs) is a routine practice, meant to prevent the potential of just such incidents from occurring. Most times, the 2 aircraft would be operating in different Controllers' "Sectors" and on different frequencies, meaning no one would have been the wiser, but "Stubbing" is required nonetheless to eliminate any chance of this overlap occurrence. One was missed, and "could have been disastrous", as was stated. This incident highlights...
"Stubbing flights" (altering 1 of the 2 call signs) is a routine practice, meant to prevent the potential of just such incidents from occurring. Most times, the 2 aircraft would be operating in different Controllers' "Sectors" and on different frequencies, meaning no one would have been the wiser, but "Stubbing" is required nonetheless to eliminate any chance of this overlap occurrence. One was missed, and "could have been disastrous", as was stated. This incident highlights the criticality of the check and balance procedures that Commercial Airline Operations instill in their staff and their tools. A mistake was made, and that process will be corrected and retrained, I can assure you.
Who exactly needs retraining?
OK, OK … I get it now. The AA Dispatcher.
Even using the same callsign or flight number for outward AND inward flights is pretty silly. Why create the possibility of confusion by doubling up? Flight numbers don't cost money - so why not just give each flight its own number - it cannot be that difficult!
Why is it allowed to have two planes with the same callsign in the air at the same time? Mind you, callsign doesn't need to equal flight number. Over here in Europe, it's quite normal for a flight to use a callsign different from its number when needed to e.g. avoid similar callsigns.
I used to work DFW Ops for legacy AA many years ago.
The Dispatcher for the PHX-ORD should've "stubbed" that flight.
In the Reservation system, nothing changes. But in the Flight Planning System (and thus the Flight Plan sent to ATC) the flight number would be altered.
A 3 digit flight number would simply have a "P" (pronounced "Papa") suffix added
The system (both AA's and ATC/FAA) can't handle more than 4 characters....
I used to work DFW Ops for legacy AA many years ago.
The Dispatcher for the PHX-ORD should've "stubbed" that flight.
In the Reservation system, nothing changes. But in the Flight Planning System (and thus the Flight Plan sent to ATC) the flight number would be altered.
A 3 digit flight number would simply have a "P" (pronounced "Papa") suffix added
The system (both AA's and ATC/FAA) can't handle more than 4 characters. So on a 4 digit number, the 1st digit gets dropped. 2482 stubbed would be 482P.
Double/triple subs can happen. The next letters used are (I think) Romeo & Sierra.
The concept for a "stub" was originally for a flight passing thru a hub, back in the days when flights were actually scheduled "thru". The inbound would be late but the hub has a spare plane so the outbound could depart on-time as a stub. Now that flight number philosophy has changed (the number doesn't go 'thru' a hub anymore, it's '"out & back", on return, the plane will go thru the hub but changes flight numbers), stub really apply more at a spoke than the hub.
I think that "stubs are now at the spoke instead of the hub" concept is what tripped the Dispatcher. While PHX is a hub, operationally for flight 2482, ORD is the hub and PHX is the spoke. If the original reason for the plane swap wasn't due to the inbound being late AND the Dispatcher was thinking of PHX as a hub, the he/she wouldn't be tracking the inbound plane thus not realizing it had lost time.
Having said that, I can't believe neither AA nor FAA's system wew able to catch this scenario developing.
What was the gender of the pilots?
That is what everybody is thinking.
Why?
Has to be satire right?
It's not the gender.
It's humans.
Aircraft have transponder codes that would have been unique in this case. They also have mode S which identify the individual aircraft regardless of what you set the transponder to. While this is a fun story it is just that.
But the transponder code isn't what displays next to the flight's blip on the controllers screen. The system does a lookup, sees that transponder code xxxx is assigned to AAL2482, thus displays AAL2482 next to the blip. Ditto for the blip of the flight assigned transponder code yyyy.
Human limitations, not the system.
Why not just give every flight a unique flight number? It is not like this is a continuation or anything. There is no logical reason why these flight numbers need to be the same. Seems like it would keep things much simpler.
Because there's an issue right now with very large airlines running out of flight numbers. United and American are both in this boat, due to designating certain flight numbers for certain tasks like regionals, code shares, etc. There are only 9999 numbers and a lot of special cases.
Spoke to a buddy on this who is a route planner and flight dispatcher for SQ. She said that this is generally not an issue these days. AA simply overlooked this potentially catastrophic problem. Airlines today use software to ensure such mishaps don’t happen. Even if all AA aircraft are in the air at the same time, there would still be 8000 other combinations left, generously. Many large airlines follow a simpler method where the...
Spoke to a buddy on this who is a route planner and flight dispatcher for SQ. She said that this is generally not an issue these days. AA simply overlooked this potentially catastrophic problem. Airlines today use software to ensure such mishaps don’t happen. Even if all AA aircraft are in the air at the same time, there would still be 8000 other combinations left, generously. Many large airlines follow a simpler method where the entire chain routing by the single aircraft is under a single flight number instead of separate numbers for each leg, exactly to avoid such a problem. AA may not do this because it would have to reshuffle the entire legacy schedule followed by sending millions of messages to passengers who may have purchased tickets, notifying of a schedule change. This may cost much more confusion. To their defense, this is a rare occurrence.
This is an obsolete system from the 1930s you're talking about. Back then they aren't that many planes.
The commercial systems (or at least, Amadeus) usually don't allow for the same flight number to be used for two different flights on the same day. For this reason, an operational suffix (as you say Ben, it's one letter appended to the flight number) is added to at least one of the flights.
AA doesn't use Amadeus, but I'm surprised Sabre allows that, I would have expected one of the two flights to have an...
The commercial systems (or at least, Amadeus) usually don't allow for the same flight number to be used for two different flights on the same day. For this reason, an operational suffix (as you say Ben, it's one letter appended to the flight number) is added to at least one of the flights.
AA doesn't use Amadeus, but I'm surprised Sabre allows that, I would have expected one of the two flights to have an operational suffix.
I don't know if the operational suffix is automatically part of the call sign, but it would be a good idea to make sure it is.
I knew airlines did this all the time, for example if the same plane is flying LGA-MSY-LGA, both flights have the same flight number. The FAA should create a rule so that, in an instance where the 1st flight is delayed and the return gets assigned to a new aircraft, it automatically gets a new flight number.
Laziness on AA's part. Their ops need to improve
Never understood the value of using the same flight number for 2 routes -- regardless of timing.
Airlines will do this often times with the flight going back and forth in 2 directions.
WHY -- are we running out of numbers in the world?
Wonder how many people will now swear that they will never fly Americal Airlines again.
Hasn't pretty much everyone done that already?
This practice of using the flightnumber for two (or more) flights is only known in the USA. Everywhere else, flightnumbers are unique. And callsigns are even more unique, because they are usually not identical with flight numbers and include a combination of numbers and letters, e.g., IB785 has the call sign IBE07WR.
I never understood the point of using the same flight number for outbound and return flights. I mean, there is an infinite supply of numbers. It's not as if the airline is going to run out! So why conserve them?
I suspect the problem might be that flight numbers are limited to 4 digits, which does impose a limit of 10,000 numbers. But the way around that is to get the systems changed to accommodate...
I never understood the point of using the same flight number for outbound and return flights. I mean, there is an infinite supply of numbers. It's not as if the airline is going to run out! So why conserve them?
I suspect the problem might be that flight numbers are limited to 4 digits, which does impose a limit of 10,000 numbers. But the way around that is to get the systems changed to accommodate bigger numbers. In this age of huge airlines with thousands of flights daily, that makes a lot of sense anyway.
Outbound flights should use 4 digits and the inbound 5.
Genius human @UncleRonnie.
So the digits change midair? And when?
Because an outbound flight from one location is an inbound to another location.
They should use 256-bit values.
That's around 115 quindecillion vigintillion unique values or 115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,564,039,457,584,007,913,129,639,936.
Of course machines can distinguish right away. Obsolete humans can't even come close.
Surprised you took so long to call on the robots today.
I think American surprised everyone (including themselves) when one of their flights was almost on time.
Even as a consumer I find it confusing when the same flight number is used for both directions. There are an unlimited number of numbers. Why can't each flight have a unique flight number? Then this kind of thing wouldn't happen.
Actually there isn't an unlimited number of numbers. Code shares (and some airlines have 5-6 code shares on certain flights) usually get a unique number similar to the original flight (e.g., AA 1234 is the same as BA 2234) so numbers are used up. Not uncommon for inbound and return to share a number and of course on direct flights (used the proper way not as a lazy name for a non-stop) multiple flights are...
Actually there isn't an unlimited number of numbers. Code shares (and some airlines have 5-6 code shares on certain flights) usually get a unique number similar to the original flight (e.g., AA 1234 is the same as BA 2234) so numbers are used up. Not uncommon for inbound and return to share a number and of course on direct flights (used the proper way not as a lazy name for a non-stop) multiple flights are under the same flight number (since that is part of the definition of a direct flight)
I've never seen the same callsign used both directions in Europe where I fly often and Asia where I sometimes fly. Perhaps it's an American thing or I've just never seen it.
Its routine in the U.S. FAA and Industry equipment limitations (currently) prohibit use of 5 characters/numbers for Commercial Airlines. Transponders assign 4-digit numbers too, but are recycled - whereas Flight schedule call signs are locked in for weeks or months at a time. Flight schedule numbers are typically only changed in FAA computers on a 56-day update cycle.
Shouldn’t ATC auto-reject the flight plan if there’s a duplicate call sign? I was on a UA flight where they had to use a different flight number for ATC for this reason.
Im certain this has happened before. Either
1. A-B-C has the same number. This is more common with southwest but I was in such a flight on AA thru PHX.
2. Back and forth hub/ spoke flights. Ive been on there before.
On #1 I can see a delayed flight get split up. The first flight is delayed but separate one starts on time. Usually they arent in the same airspace.
I was on a...
Im certain this has happened before. Either
1. A-B-C has the same number. This is more common with southwest but I was in such a flight on AA thru PHX.
2. Back and forth hub/ spoke flights. Ive been on there before.
On #1 I can see a delayed flight get split up. The first flight is delayed but separate one starts on time. Usually they arent in the same airspace.
I was on a east coast-PHX-west coast flight. Both legs had the same number but they did an equip change in phx so we had to leave the plane with crew escorts to the new plane
This thing has been much more common in southwest. Like I was on a flight thru Denver as a stop then onto next airport. My flight was delayed getting inyo denver then they flipped planes si I missed connection
Sometimes airlines can under #2 cancel the flight, then rebook everyone on a different flight number newly created.
given that airlines are running out of flight numbers due to codesharing, it is common for an inbound and outbound leg of a flight to use the same flight number.
it is the airline's responsibility to file a different flight number even if, as Ben notes, adding a letter to one of them
someone at AA didn't realize the inbound would not be on the ground by the time the outbound departed and they apparently do not have automated systems to warn them if this does happen.
Surprised there's not a FAA regulation that doesn't allow two call signs for the same airline in air at the same time. For this reason.
Agreed. I wonder how they even differentiate internally at AA: things like fuel supply, catering, etc, even post-flight incident reports (in case there's an emergency that needs extra reporting after the fact) or baggage handling. This could go disastrously wrong.
This is why many airlines use alphanumeric callsigns now....
That's why humans should be eliminated and callsigns are at least a 256-bit value.
Too many airplanes , too much everything ; cut back 50% to a reasonable amount .
Is your prompt set to: "read article; absurd idea"?
Cut back on beardeys and girl food to .