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How does flight numbering decide whether continuation leg gets new UA flight number?

How does flight numbering decide whether continuation leg gets new UA flight number?

Old Apr 22, 2024, 12:12 am
  #1  
TA
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How does flight numbering decide whether continuation leg gets new UA flight number?

Example (just to be clear what I mean):

UA 2166 is a flight number that (within a single day) gets attached to:
  • PHX-SFO
  • SFO-EWR
  • EWR-IAD
And they're different physical planes.

Why do they choose to keep the flight number the same, versus give these legs different flight numbers?

Just curious!
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Old Apr 22, 2024, 12:58 am
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The short answer is there are no enought flight numbers for all the flights to be unique.

Additional this allows selling UA2166 as SFO-IAD as a Direct, 1-stop flight. I suspect this later characteristic is part of the decision when to offer.
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Last edited by WineCountryUA; Apr 22, 2024 at 10:13 am Reason: typo
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Old Apr 22, 2024, 4:56 am
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1 through 9999

going beyond that is an airline IT Y2K problem. But one that is really only significant for the big 3.
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Old Apr 22, 2024, 5:02 am
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Originally Posted by WineCountryUA
Additional this allows sell UA2166 as SFO-IAD as a Direct, 10stop flight. I suspect this later characteristic is part of the decision when to offer.
Oof...
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Old Apr 22, 2024, 5:33 am
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Originally Posted by whlinder
1 through 9999

going beyond that is an airline IT Y2K problem. But one that is really only significant for the big 3.
I think UA is only using 1 to 2999 for regularly scheduled mainline flights. Might not be even that expansive.
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Old Apr 22, 2024, 6:40 am
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Love the fact that some of the low flight numbers 19&20, 54&55, 56&57, are TATL flights numbers dated back to Continental.
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Old Apr 22, 2024, 7:30 am
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Usually there should be sufficient block time in between these "direct" flights, but once in a while, there will be two flights in the air with the same flight number.

For example, UA498, preforming STL to DEN, and then DEN to PDX - on Saturday, April 20, 2024, STL to DEN was late, which resulted in two UA498 in the air for a period of time. I actually think the DEN to PDX flight waited a bit before taking off; though can't be absolutely certain:

STL to DEN: landing at 739pm; gate arrival 747pm
DEN to PDX: gate departure 709pm; take off 738pm
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Old Apr 22, 2024, 9:50 am
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Originally Posted by TA
Why do they choose to keep the flight number the same, versus give these legs different flight numbers?
They've got more flights than available flight numbers.

Originally Posted by JimInOhio
I think UA is only using 1 to 2999 for regularly scheduled mainline flights. Might not be even that expansive.
There's some carve-outs in there too that aren't usable for scheduled flights.
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Old Apr 22, 2024, 9:59 am
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Originally Posted by mduell
...There's some carve-outs in there too that aren't usable for scheduled flights.
Like "13", "69", and "666"
"911", also.
They're usable, but UA chooses not to use them, for various reasons.
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Last edited by IAH-OIL-TRASH; Apr 22, 2024 at 10:04 am
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Old Apr 22, 2024, 10:01 am
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While it is a few years old the United Cargo website has ranges for United and United Express flight, scroll to the bottom of the page.
https://www.unitedcargo.com/en/us/book/schedules.html

Remember many flights in the higher ranges are codeshares and cannot be used for United metal.

In reservation systems a non-stop will show first, a direct second and connecting third. Direct flights have been used on routes to try to show earlier in the results in GDS. Less of a factor now, but that was a huge concern in the past.
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Old Apr 22, 2024, 10:29 am
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Originally Posted by ncorman
In reservation systems a non-stop will show first, a direct second and connecting third. Direct flights have been used on routes to try to show earlier in the results in GDS. Less of a factor now, but that was a huge concern in the past.
I believe they also show first when using some searches because they are not subject to additional taxes/fees that apply per segment.

So when flight results are sorted by price, they appear higher in the list than a connecting flight with the same base fare.
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Old Apr 22, 2024, 11:40 am
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Originally Posted by IAH-OIL-TRASH
Like "13", "69", and "666"
"911", also.
They're usable, but UA chooses not to use them, for various reasons.
While 1776 and 1492 are reserved for Philadelphia and Columbus, respectively. I always thought 1906 should be reserved for SFO. Some numbers get retired, when something bad happens.
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Old Apr 22, 2024, 11:44 am
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Originally Posted by ContinentalFan
While 1776 and 1492 are reserved for Philadelphia and Columbus, respectively. I always thought 1906 should be reserved for SFO. Some numbers get retired, when something bad happens.
888 is definitely a good number to Beijing.
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Old Apr 22, 2024, 12:09 pm
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Originally Posted by IAH-OIL-TRASH
888 is definitely a good number to Beijing.
And 317 to Dublin!!
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Old Apr 22, 2024, 12:23 pm
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Originally Posted by whlinder

going beyond that is an airline IT Y2K problem.
And ATC as well as IATA. There's a limit to the size of the flight identifier field in an ATC data tag, by international treaty/agreement (ICAO and IATA). AAANNNNZ
AAA: The 3-letter airline identifier. (though it's usually 2)
NNNN: The flight number (1-4 digits)
Z: The "operational suffix". Covers situations where a flight is so delayed, it bumps into the next scheduled flight of that number. So one of the 2 gets an additional letter in the flight strip (usually "D", "X", or "Y").

Edit: Found the ICAO reference. "not exceeding 7 alphanumeric characters and without hyphens or symbols". So AANNNNZ is right at 7 characters.
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Last edited by RandomNobody; Apr 22, 2024 at 12:35 pm
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