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IrishAyes
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Why Do Airlines Re-use Flight Numbers?

Tue Nov 18, 2014 6:54 pm

I've noticed a phenomenon recently (particularly on American and Delta) where the airline will utilize the same flight number multiple times between city pairs in a single day, even though the origin and destination is different in each case.

For example, on Sunday, November 16, American Airlines AA 2306 operated as DFW-MSP as well as the return flight, MSP-DFW.

Another example: on Wednesday, November 26, Delta Air Lines flight DL 2075 operates as ATL-MCI as well as the return flight, MCI-ATL.

My most educated guess for this is due to the availability of numbers less than 3000 that correspond to mainline ops. After airlines like American and Delta merged with their respective partners, they essentially had double the number of mainline flights to accommodate under those numbers, so they reused them between hub-and-spoke city pairs like ATL-KCI or DFW-MSP since often times the inbound equipment, crew, etc was also used on the outbound?

Any info would be appreciated!
 
AeroWesty
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RE: Why Do Airlines Re-use Flight Numbers?

Tue Nov 18, 2014 7:42 pm

The usual answer to this question is for flight number conservation, considering how many banks of flight numbers need to be reserved for codeshares. This has been going on for a long time, as evidenced by the below thread on another forum dating back a decade ago:

Same Flight Number, Yet a Roundtrip. Why?
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iahcsr
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RE: Why Do Airlines Re-use Flight Numbers?

Tue Nov 18, 2014 7:59 pm

UA does the same and for the same reasons
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jetblue1965
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RE: Why Do Airlines Re-use Flight Numbers?

Tue Nov 18, 2014 8:03 pm

what happens if the inbound is delayed but return flight is on-time ? would 2 planes with the same flight number be in the air ?
 
MesaFlyGuy
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RE: Why Do Airlines Re-use Flight Numbers?

Tue Nov 18, 2014 8:17 pm

Quoting jetblue1965 (Reply 3):

With Delta and American, most of them are operated by the same plane, so both flights would be delayed. I've noticed United scheduling it so a different plane will operate the two legs and if one is delayed they will slightly alter the flight numbwr, like making flight 4035 into 435P or something similar. However, most of the time I see United do this, they schedule enough downtime between legs to mitigate potential delays. I've seen a flight # come in from a hub and have three or four hours until its return.
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Yflyer
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RE: Why Do Airlines Re-use Flight Numbers?

Tue Nov 18, 2014 8:20 pm

I think when they do this the plane is usually routed hub-spoke-hub in an out and back routing so if the first leg is delayed then the second one is delayed as well. SkyWest does this with many of the short Brasilia flights out of SFO, for example SFO-SMF-SFO is all the same flight number. The SMF-SFO flights are notorious for being delayed due to the inbound aircraft being late.

Edit: In other words when the post above mine said. I swear it wasn't there when I started typing my reply.

[Edited 2014-11-18 12:22:20]
 
SPREE34
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RE: Why Do Airlines Re-use Flight Numbers?

Tue Nov 18, 2014 8:38 pm

Quoting jetblue1965 (Reply 3):
what happens if the inbound is delayed but return flight is on-time ? would 2 planes with the same flight number be in the air ?

If they were, the radio callsigns would not be the same. The usual fix is to replace a number with a letter. i.e.: DL2075 and DL207A, or similar.
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speedbird2263
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RE: Why Do Airlines Re-use Flight Numbers?

Tue Nov 18, 2014 9:28 pm

Quoting SPREE34 (Reply 6):

This is correct. For ATC purposes the flight is "stub-amended" to contain an alpha-numeric identifier. In domestic cases it is usually used quite often whereas one leg of the flight is delayed and yet to operate and the next leg is set be operated by another aircraft while the previous flight is active.

It is often used with International Flights as well, I have noticed stub-amended call signs used regularly with BA. I can only assume that given the large distances any delay may easily cross over in the next schedule of the flight with the same flight number.

  
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CXfirst
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 1:13 am

Quoting speedbird2263 (Reply 7):
It is often used with International Flights as well, I have noticed stub-amended call signs used regularly with BA. I can only assume that given the large distances any delay may easily cross over in the next schedule of the flight with the same flight number.

I was listening to LiveAtc once here in Australia, when a QF10 (DXB-MEL), which was already delayed made a medical diversion to PER. After they took off again, midflight, ATC asked the crew to now use the callsign QF10D, as QF10 had just taken off from DXB. First time I've heard ATC ask for an airline to change its callsign midflight.
 
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enilria
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 1:23 am

There is a limit of 9999 available flight numbers. The proliferation of code shares has made it impossible to code share everything they want to code share if you are talking a legacy airline in an alliance. That conservation might have allowed the AA code into BLR.
 
29erUSA187
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 1:23 am

AA49 is the same way. It operates CDG-DFW on a 763, then a 752 to SAN.
 
Viscount724
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 1:37 am

Quoting speedbird2263 (Reply 7):
It is often used with International Flights as well, I have noticed stub-amended call signs used regularly with BA. I can only assume that given the large distances any delay may easily cross over in the next schedule of the flight with the same flight number.

Some airlines always use a different flight number for operational/ATC purposes than the marketing flight number used for reservations/ticketing. For example, KLM flight 692 YYZ-AMS always operates as KLM 32.

i expect that may be because they have so many flights with similar flight numbers in the 600 series departing various points in North America that converge over the North Atlantic at roughly the same time that using the marketing flight number might cause confusion and create potential safety issues with aircraft accepting a clearance intended for another flight with a similar number.
 
MesaFlyGuy
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 2:00 am

Quoting 29erUSA187 (Reply 10):
AA49 is the same way. It operates CDG-DFW on a 763, then a 752 to SAN.

That's a different scenario, but also very common.
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hongkongflyer
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 4:00 am

May be in future we will see the English letters in the flight number,
DL55E3 flight from XXX to YYY....
 
tylersmithsjc
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 6:36 am

AA operates AA47 which is both ORD-LHR and ORD-SJC. Some errors on Flightradar24 have displayed that a 772 is operating ORD-SJC when it's just a 737.
SJC/CLD
 
jimbobjoe
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 7:20 am

I thought that this practice also inflated on-time statistics.

If DL 2075 is ATL-MCI-ATL the flight is considered on time if it arrives timely in ATL, what happens in MCI isn't factored in.

I read somewhere that's why southwest uses one flight number for a bunch of different flights....the on time statistics are based on the last leg of that flight, what happens in the middle doesn't count.
 
blueflyer
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 8:10 am

European charter airlines do this as well. Many assign a number to a city pair (say 543 for LGW-PMI) then will prepend a digit to indicate the day of the week the flight is operating on (since schedules can change from day to day). So a LGW-PMI-LGW rotation on a Monday will be 1543. If they need to differentiate inbound and outbound flights, they'll append a letter, usually the same based on whether the flight is inbound or outbound. I think Monarch adds a P to all outbound flights for example.

Quoting Viscount724 (Reply 11):
i expect that may be because they have so many flights with similar flight numbers in the 600 series departing various points in North America that converge over the North Atlantic at roughly the same time that using the marketing flight number might cause confusion and create potential safety issues with aircraft accepting a clearance intended for another flight with a similar number.

You're correct. It's not just to avoid confusion between two company flights however, but between different airlines. Pilots aren't focused on their radio at all times, so there might be a moment of confusion between Delta 632 and Lufthansa 622 when a controller calls unexpectedly.

Lufthansa is actually notorious for using call signs that very often have little to no relation whatsoever with the advertised flight number. If you were to look at its short/mid-haul flights in the air right now, you'd notice few operating under a call sign that even resembles the advertised flight number. Sure, there's a 836 or 940 to be found, but call signs like 1E or 4HU are far more common.
 
Honza
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 10:46 am

Hi,

back in 2010 our flight MIA-JFK-PRG was designated DL208 for both segments.

And regarding the recently popular "numbers+letters" callsigns, just yesterday I had two different flights in my sector (one was Lufthansa and the other one I don't remember, possibly LOT) and both had callsign "5HW". Of course there was a confusion with the pilots as which clearance is for whom   This happens a lot nowadays that these wannabe-unique callsigns meet on the same frequency.

Best regards,

Honza
 
simairlinenet
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 2:53 pm

Quoting irishayes (Thread starter):
The usual answer to this question is for flight number conservation, considering how many banks of flight numbers need to be reserved for codeshares.

This is the commonly quoted answer (even by airlines themselves), but is there anyone else that doesn't believe this?

American: 6700 flights/day http://www.aa.com/i18n/amrcorp/corpo...on/facts/americanairlinesgroup.jsp
United: 5166 http://newsroom.unitedcontinentalholdings.com/corporate-fact-sheet
Delta: 5400 http://news.delta.com/index.php?s=20306

Looking at their most recent timetables, each of these airlines uses the following flight ranges:
American: can't tell, ranges are not listed--this one is probably up near 100% though
United: 1-6548 (79% utilization)
Delta: 1-999, 1051-4299, 4451-6399 (87%)

Surely there's not a true need for as many repeated flight numbers as we actually see--it's more a matter of convenience.

[Edited 2014-11-19 07:35:51]
 
planespotting
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 3:06 pm

Didn't this use to be a marketing thing back 10-plus years ago? For instance, my Northwest timetables from the 90s show same plane/same flight number service between DSM and stations like DFW (via MSP), and other random city pairs.
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nkops
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 3:28 pm

Quoting tylersmithsjc (Reply 14):
AA operates AA47 which is both ORD-LHR and ORD-SJC

On the same day?
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jetblue1965
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 3:33 pm

lack of numbers is one main reason, but a side benefit (albeit small one) is not having to pay the proper miles :

When you book a "direct" UA flight number of EWR-IAH-SEA, they'll only pay you the miles of the EWR-SEA great circle distance instead of giving you credit for your detour.
 
DTWPurserBoy
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 3:37 pm

Quoting jetblue1965 (Reply 3):






what happens if the inbound is delayed but return flight is on-time ? would 2 planes with the same flight number be in the air ?

Yes. For instance if DL236 DTW-AMS on 11/19 were delayed due to a mechanical and actually departed the afternoon of 11/20, it would still be DL 236 of 11/19 and DL 236 of 11/20 would operate as well.

Quoting 29erUSA187 (Reply 10):
AA49 is the same way. It operates CDG-DFW on a 763, then a 752 to SAN.

That is called a "change of gauge" meaning that the flight number continues but the type of aircraft changes. For example, NW 12 used to be a 747-400 NRT-DTW and then changed to an A320 DTW-DCA. People would ask me "Well, why don't they just keep the 744 all the way to DCA?" My response would always be "Because it would stop rolling somewhere around The White House."
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GCT64
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 3:44 pm

Quoting speedbird2263 (Reply 7):
It is often used with International Flights as well, I have noticed stub-amended call signs used regularly with BA.

European use is for slightly different reasons, to reduce callsign confusion in sectors and at airports, so a particular flight will be systematically changed to a alpha-numeric. e.g. LH914 FRA-LHR always operates with the ATC callsign DLH9KA.

ATC European Callsigns? (by wardialer Apr 2 2011 in Tech Ops)
Ryanair Flight Numbers (by spencer Mar 15 2011 in Tech Ops)
and a few other threads over the years.
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brilondon
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 6:10 pm

UAX 5508 is the flight number from ORD to YXU to ORD. Now you would never have the same flight number in the sky because it is the same plane that does that flight. I assume it has something to do with the aircraft they are using adn why not it is not like you are going to be confused unless you are stupid.
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DAL763ER
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 6:24 pm

Quoting nkops (Reply 20):

Quoting tylersmithsjc (Reply 14):
AA operates AA47 which is both ORD-LHR and ORD-SJC

On the same day?

It's LHR-ORD and ORD-SJC. This is the scenario where the airline markets flight 123 from AAA to CCC as a direct flight (but with a change of planes in BBB). Helps the airline but screws over the customer. Miles would be awarded accordingly and I think it also only counts as one segment.

BA does this for LHR-SYD on flight 15. You can fly BA #15 from LHR to SYD direct, but you'd get off the plane for some fresh air in SIN. From a marketing perspective, it's direct. As a customer, BA steals miles and tier points for whoever books the "direct" option.
 
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JBo
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RE: Why Do Airlines Re-use Flight Numbers?

Wed Nov 19, 2014 6:28 pm

Quoting hongkongflyer (Reply 13):
May be in future we will see the English letters in the flight number,
DL55E3 flight from XXX to YYY....

I've thought about this as well, but the one issue with implementing alphanumeric flight numbers is that the letters can be phonetically confusing when making gate announcements, etc. I think it's more likely that reservations systems will be upgraded to handle 5-digit flight numbers.
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