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Letters After Flight Numbers  
User currently offlineDr.DTW From United States of America, joined May 2000, 290 posts, RR: 1
Posted (5 years 7 months 3 weeks 1 day 21 hours ago) and read 10297 times:

What do the letters after flight numbers mean??

On JFK Tower, I just heard: "United 893 Lima," and later I heard: "United 891 Charlie"

Some explanations I've read, which don't fit include:

1. This segment of the flight was significantly delayed, and the second segment is simultaneously in the air in another part of the country. Both of these flights were reasonably on-time, and second segment was not airborne.
2. The company is using similar flight numbers at the same time. I can't imagine this being an explanation. We always hear same company flight numbers differing by one number on the same frequencies, without letter designations used for differentiation.

Are there other reasons why companies do this ?

Thanks
Ed.

24 replies: All unread, jump to last
 
User currently offlineBigSaabowski From United States of America, joined Jul 2008, 160 posts, RR: 0
Reply 1, posted (5 years 7 months 3 weeks 1 day 21 hours ago) and read 10275 times:



Quoting Dr.DTW (Thread starter):
2. The company is using similar flight numbers at the same time. I can't imagine this being an explanation. We always hear same company flight numbers differing by one number on the same frequencies, without letter designations used for differentiation.

That's it. The aircraft are following the same route across 3/4ths of the country at the same time. It's too easy to confuse "United 891" and "United 893". You're right, most other airlines don't do this.


User currently offlineBramble From , joined Dec 1969, posts, RR:
Reply 2, posted (5 years 7 months 3 weeks 1 day 21 hours ago) and read 10232 times:

In Europe some airlines substitute a letter for a number of the 'civilian' flight number .
E.G. The public are booked on EI-164 DUB-LHR but it is known to ATC as Shamrock 16 golf. This was adopted out of Dublin,I believe, as two airlines had a lot of similar flight numbers out of DUB, so EI agreed to alter their flight planning.

In addition EI often add letters to flights numbers to signify a non scheduled flight. E.G. EI-164 may get to LHR,normally it returns as EI165,however if it had to ferry back empty it will either have an additional number (EI2165) or a letter (EI165P) Flights that are diverted usually have a letter added to the original flight number for the second sector to the original destination.


User currently offlineAmricanShamrok From Ireland, joined May 2008, 3004 posts, RR: 0
Reply 3, posted (5 years 7 months 3 weeks 1 day 20 hours ago) and read 10192 times:

Y2 tend to do this with alot of their flights. I know the letter P comes after some of their numbers meaning it's a positioning flight but not sure about other letters...

[Edited 2009-05-02 07:13:45]


Shannon-Chicago
User currently offlineAAMDanny From United Kingdom, joined Apr 2008, 376 posts, RR: 0
Reply 4, posted (5 years 7 months 3 weeks 1 day 20 hours ago) and read 10139 times:

Thomas Cook Airlines (TCX) use K and L after each flight number.

K represents the Outbound Sector (e.g. TCX555K would be something like BHX-DLM)
L represents the Inbound Sector, adopting the same flight number (e.g. TCX555L DLM-BHX)

Flight numbers ending in H/G represent a TCX corporate charter flight/ad-hoc. G for outbound and H for inbound.

This is easier for crew, they only have to remember one flight number, and just add on the appropiate letter at the end of each flight number.
-------------------------------------------------
Air 2000 (AMM) years ago used to have 'C' added to the end of there flights numbers too, however Im not 100% certain on why th is was, I can only imagine it was to distinguish holiday charter flights?!

Quoting AmricanShamrok (Reply 3):
Y2 tend to do this with alot of their flights. I know the letter P comes after some of their numbers meaning it's a positioning flight but not sure about other letters...

P is the most common, most airlines make there flights distinguised as a posistioning flight by adding P.


User currently offlineSmcmac32msn From United States of America, joined May 2004, 2211 posts, RR: 4
Reply 5, posted (5 years 7 months 3 weeks 1 day 19 hours ago) and read 10094 times:



Quoting BigSaabowski (Reply 1):
That's it. The aircraft are following the same route across 3/4ths of the country at the same time. It's too easy to confuse "United 891" and "United 893". You're right, most other airlines don't do this.

I'm sure its more common to miss "United 91" and "United 891" and United 1891" than it is "891" and "893"



Hey Obama, keep the change! I want my dollar back.
User currently offlineAAMD11 From UK - Wales, joined Nov 2001, 1061 posts, RR: 1
Reply 6, posted (5 years 7 months 3 weeks 1 day 19 hours ago) and read 10077 times:



Quoting AAMDanny (Reply 4):
Thomas Cook Airlines (TCX) use K and L after each flight number.

I had noticed that on the flight into YOW from LGW... it's 16K inbound and 16L outbound, I think.

Probably allows you to have many more flight numbers if it's just one number per pairing, with a letter to identify the different segments on the return trip.


User currently offlineBA777 From United Kingdom, joined Jun 2001, 2181 posts, RR: 7
Reply 7, posted (5 years 7 months 3 weeks 1 day 18 hours ago) and read 9980 times:

Air 2000 used to do 'C' and 'D' For example 92C was LGW-STT-ANU and then 92D for ANU-LGW i believe.

User currently offlineBananaboy From United Kingdom, joined Oct 2004, 1587 posts, RR: 22
Reply 8, posted (5 years 7 months 3 weeks 1 day 17 hours ago) and read 9903 times:



Quoting AAMDanny (Reply 4):
Air 2000 (AMM) years ago used to have 'C' added to the end of there flights numbers too, however Im not 100% certain on why th is was, I can only imagine it was to distinguish holiday charter flights?!

I don't believe that was the case, as all AMM flights were charter flights.. they used the code DP for scheduled services.

Quoting BA777 (Reply 7):
Air 2000 used to do 'C' and 'D' For example 92C was LGW-STT-ANU and then 92D for ANU-LGW i believe.

 checkmark 

Britannia also used "A" for outbound and "B" for inbound. Why Britannia used A/B, Air 2000 C/D and Thomas Cook K/L remains a mystery to me. Could they not have all justed used A/B?

Mark



All my life, I've been kissing, your top lip 'cause your bottom one's missing
User currently offlineLabswalker From United States of America, joined Dec 2008, 24 posts, RR: 0
Reply 9, posted (5 years 7 months 3 weeks 1 day 17 hours ago) and read 9857 times:

Sometimes flights originate out of a city with a flight number say flight 81 CLE-EWR it may be a 737. Later in the day Flight81 continues to another city say EWR-MIA. If 81 gets delayed in CLE and is not yet in EWR when 81 departs EWR, then it becomes 81A or 5081 or some other designation so the same airline doesn't have 2 flights the same number airborne at the same time.

Hope that helps explain it, here in the US anyway.


User currently offlineYLWbased From Hong Kong, joined Jan 2006, 844 posts, RR: 4
Reply 10, posted (5 years 7 months 3 weeks 1 day 16 hours ago) and read 9843 times:

i know in HKG they uses "D" for delayed flights.
e.g. CX838D

YLWbased



Hong Kong is not China. Not better or worse, just different.
User currently offlineMPDPilot From United States of America, joined Jul 2006, 1005 posts, RR: 0
Reply 11, posted (5 years 7 months 3 weeks 1 day 3 hours ago) and read 9564 times:

I know British Airways for ATC purposes uses "Speedbird 9CG" to PHX. But the British Airways flight number is 289. I don't get this and like the thread starter have always wondered why.


One mile of highway gets you one mile, one mile of runway gets you anywhere.
User currently offlineBMI727 From United States of America, joined Feb 2009, 15831 posts, RR: 27
Reply 12, posted (5 years 7 months 3 weeks 1 day 3 hours ago) and read 9541 times:

For the case of the original poster, I should point out that UA operates many change of guage flights. For example, UA 888 is a 777 flight from Beijing to San Francisco and an A320 flight between SFO and LAX. Normally there is no conflict. But if the flight from PEK is delayed and both segments will be in the air at the same time, the SFO-LAX flight may use a letter after the flight number to avoid confusion.

Quoting AAMDanny (Reply 4):
P is the most common, most airlines make there flights distinguised as a posistioning flight by adding P

This seems rarer in the US. Here most test or repositioning flights just use a 9xxx callsign.

Quoting BigSaabowski (Reply 1):
It's too easy to confuse "United 891" and "United 893".

I have also heard of ATC requesting that the airline change a flight number if two similar ones (like 1011 and 1101) are scheduled to be in the same area at a given time.



Why do Aerospace Engineering students have to turn things in on time?
User currently offlineViscount630 From United Kingdom, joined Mar 2005, 239 posts, RR: 0
Reply 13, posted (5 years 7 months 3 weeks 1 day 3 hours ago) and read 9488 times:
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Quoting MPDPilot (Reply 11):
I know British Airways for ATC purposes uses "Speedbird 9CG" to PHX. But the British Airways flight number is 289. I don't get this and like the thread starter have always wondered why.

I'm not sure, but I THINK this goes back to BOAC days. They used to use a complicated formula to label flights by the route and the sector on that route in a particular date/period for the records, and used the "Flight Number" for reservations purposes and on the tickets etc?

Hopefully someone somewhere can explain it a bit clearer.....  Wink



RIP Dan-Air. Where the Secret was SERVICE.
User currently offlineBramble From , joined Dec 1969, posts, RR:
Reply 14, posted (5 years 7 months 3 weeks 20 hours ago) and read 8375 times:

In addition EI used to operate European flights out of Ireland via another Irish airport. For example EI 692 was ORK-DUB-DUS. The flights numbers were EI692A ORK-DUB then EI692B DUB-DUS. The return was EI693A and EI693B.

User currently offlineChase From United States of America, joined Nov 2005, 1054 posts, RR: 0
Reply 15, posted (5 years 7 months 3 weeks 20 hours ago) and read 8356 times:

At TZ, we used to suffix letters onto flights in the event of unusual operations such as flights that turned back to the originating airport after takeoff. I don't know how this worked from an ATC perspective - I worked in the datacenter and got the flight numbers after the fact. But for instance, if flight 123 was planned IND-PIE but had to return to IND immediately after takeoff, all our scheduling and reporting systems would see two flights: 123A IND-IND (which was 123 at the time it took off) and the second attempt which actually succeeded would be 123 IND-PIE. I think I remember seeing one that got up to "C" once...must have been a fun day for those pax!

User currently offlineBMI727 From United States of America, joined Feb 2009, 15831 posts, RR: 27
Reply 16, posted (5 years 7 months 3 weeks 20 hours ago) and read 8337 times:



Quoting Chase (Reply 15):
I don't know how this worked from an ATC perspective

I think that they would use the same flight number the whole time, unless the flight continued with a different aircraft and there was a chance both could be up at the same time.



Why do Aerospace Engineering students have to turn things in on time?
User currently offlineMir From United States of America, joined Jan 2004, 21864 posts, RR: 55
Reply 17, posted (5 years 7 months 3 weeks 18 hours ago) and read 8279 times:



Quoting Dr.DTW (Thread starter):
Some explanations I've read, which don't fit include:

1. This segment of the flight was significantly delayed, and the second segment is simultaneously in the air in another part of the country. Both of these flights were reasonably on-time, and second segment was not airborne.

This is why UA does it, but it's not dependent on a flight being delayed. It's so that in case there is a delay on the JFK-SFO leg of UA893, there won't be any flight number conflict with the SFO-ICN leg, which is operated by a different aircraft. Flight plans are filed well before a flight actually departs, so even if delays are not expected at the time of filing, something could come up (especially when JFK is involved). So it's better to just add the letter anyway.

Quoting BMI727 (Reply 12):
I have also heard of ATC requesting that the airline change a flight number if two similar ones (like 1011 and 1101) are scheduled to be in the same area at a given time.

Air India 111 and Aer Lingus 111 used to arrive at JFK at about the same time. Sometimes, one would be following the other on final - a very good opportunity for confusion. The flight numbers for both are still 111, but now the Aer Lingus flight uses 11C when talking to ATC.

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offlineArgonaut From UK - Scotland, joined Dec 2004, 422 posts, RR: 1
Reply 18, posted (5 years 7 months 3 weeks 17 hours ago) and read 8231 times:



Quoting Viscount630 (Reply 13):
I'm not sure, but I THINK this goes back to BOAC days. They used to use a complicated formula to label flights by the route and the sector on that route in a particular date/period for the records, and used the "Flight Number" for reservations purposes and on the tickets etc

I don't want to drift too far O/T, but this is interesting, and I suspect is connected to something I particularly recall about BOAC flight numbers:

For internal purposes, BOAC allocated an extension to the flight number to indicate the "trip number". This showed chronologically which exact flight it was under that particular flight number since the service/route first appeared in the timetable. So, for instance, flight BA256-41 indicated the 41st individual journey operated under flight number BA256. I used to see it sometimes on the passenger flight-progress sheets that used to be passed around the cabin (as old-timers might recall!) and when I once asked the crew about it, that's the explanation I got. I don't know how many other airlines followed this practice, but I do have a similar card from the early 1950s for the United SFO-HNL service that shows a similar "journey number" (along with the names of all the passengers on board!).

rj



'the rank is but the guinea stamp'
User currently offlineMcdu From United States of America, joined Apr 2005, 1487 posts, RR: 17
Reply 19, posted (5 years 7 months 3 weeks 17 hours ago) and read 8219 times:



Quoting BigSaabowski (Reply 1):
That's it. The aircraft are following the same route across 3/4ths of the country at the same time. It's too easy to confuse "United 891" and "United 893". You're right, most other airlines don't do this.

Actually that is not correct. The use of "Charlie","Lima" etc at UAL is to distinguish if the flight has a international connection. In the case of 893 it operates to LAX and then the same flight number continues on to NRT and BKK. There can not be two 893 in the ATC system at one time. In the event that the domestic portion might be delayed the company will assign the domestic flight a suffix to the flight number OR we will us a 81XX number for the domestic portion.

This is not due to confusion over 891 and 893. We are quite capable of distinguishing those two flight numbers. This is all about the continuation flight into international segments. Other carriers do add suffixes to their flights also. Quite often I will hear AA with a phonetic addition over the Atlantic.


User currently offlineYak97 From United Kingdom, joined Sep 2005, 118 posts, RR: 0
Reply 20, posted (5 years 7 months 3 weeks 17 hours ago) and read 8205 times:

The UK CAA, some years ago, produced a study on ATC flight numbers as there had been cases of aircraft mistakenly following another aircraft's instructions because of the same flight number. Adding the full call sign to each transmission would have increased the time each ATC transmission takes, which is a problem in a high work-load area such as around London. Historically airlines tended to run flight numbers in a sequence so, for example, 101/102 would be the morning, 103/4 lunchtime & 105/6 the evening, which makes it simple for passengers, but could lead to confusion if 3 or 4 airlines had flights in the air at the same time with similar flight numbers.
This led to a disconnection between the commercial flight numbers that passengers see and the call-signs for ATC purposes. By adding suffix letter/s to a callsign it 1) decreased the likelyhood of 2 identical call-signs & 2) increased the number of call signs available to airlines.
Best practise says that flight numbers should avoid 1 - 360 (degree's of heading), 900 -1100 (pressure settings).
4 number callsigns are often used by airlines to indicate charter flights, with the flight number being used once only & sometimes with a different number for each sector


User currently offlineCloudyapple From Hong Kong, joined Jul 2005, 2454 posts, RR: 10
Reply 21, posted (5 years 7 months 3 weeks 16 hours ago) and read 8178 times:



Quoting Yak97 (Reply 20):
The UK CAA, some years ago, produced a study on ATC flight numbers as there had been cases of aircraft mistakenly following another aircraft's instructions because of the same flight number. Adding the full call sign to each transmission would have increased the time each ATC transmission takes, which is a problem in a high work-load area such as around London. Historically airlines tended to run flight numbers in a sequence so, for example, 101/102 would be the morning, 103/4 lunchtime & 105/6 the evening, which makes it simple for passengers, but could lead to confusion if 3 or 4 airlines had flights in the air at the same time with similar flight numbers.
This led to a disconnection between the commercial flight numbers that passengers see and the call-signs for ATC purposes. By adding suffix letter/s to a callsign it 1) decreased the likelyhood of 2 identical call-signs & 2) increased the number of call signs available to airlines.
Best practise says that flight numbers should avoid 1 - 360 (degree's of heading), 900 -1100 (pressure settings).
4 number callsigns are often used by airlines to indicate charter flights, with the flight number being used once only & sometimes with a different number for each sector

This is the study:
http://www.caa.co.uk/application.asp...pe=65&appid=11&mode=detail&id=1244

And as a result we issued these guidelines:
http://www.levelbust.com/downloads/callsign_confusion_article.pdf



A310/A319/20/21/A332/3/A343/6/A388/B732/5/7/8/B742/S/4/B752/B763/B772/3/W/E145/J41/MD11/83/90
User currently offlineSAAB900 From United Kingdom, joined Sep 2007, 490 posts, RR: 0
Reply 22, posted (5 years 7 months 3 weeks 13 hours ago) and read 8079 times:

Lufthansa's MAN flights are the same. For example DLH4851 alpha-numeric call sign is DLH6LX! Like Ed I've also been curious to know the reasons behind these!

Dave(SAAB900)


User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 23, posted (5 years 7 months 3 weeks 11 hours ago) and read 7979 times:

Bottom line!

Quoting Labswalker (Reply 9):
Sometimes flights originate out of a city with a flight number say flight 81 CLE-EWR it may be a 737. Later in the day Flight81 continues to another city say EWR-MIA. If 81 gets delayed in CLE and is not yet in EWR when 81 departs EWR, then it becomes 81A or 5081 or some other designation so the same airline doesn't have 2 flights the same number airborne at the same time.

It doesn't matter where in the U.S. those flights are, the chance that they could both end up in the same enroute sector after a weather re-routing or in adjacent sectors where confusion may arise when addressing the same flight number, so it is best to add a letter to the end, or my preference is to do as Labswalker mentions above.

Quoting BMI727 (Reply 12):
I have also heard of ATC requesting that the airline change a flight number if two similar ones (like 1011 and 1101) are scheduled to be in the same area at a given time.

CO did a fabulous job a few years ago in eliminating similar sounding call signs from their HUBS.....IAH used to get stuff like CO1878, 1678, 678, 1568 all leaving at the same time and heading in the same direction for hours....marketing got involved and a guru of scheduling modified almost the entire banks to eliminate the problem.

CO took things like IAH-LAX and made almost all of those flights end in 95, so 495, 695, 1495 etc., which are all scheduled an hour or so/more apart. Pretty nice job they did. IAH doesn't have too much of a problem any more with this unless there are delays and you end up with 2 or 3 flights headed to the same city close together.

[Edited 2009-05-03 16:13:29]


Any views shared are strictly my own and do not a represent those of any former employer.
User currently offlineDogfighter2111 From United Kingdom, joined Nov 2004, 1968 posts, RR: 1
Reply 24, posted (5 years 7 months 3 weeks 11 hours ago) and read 7967 times:



Quoting AmricanShamrok (Reply 3):
Y2 tend to do this with alot of their flights. I know the letter P comes after some of their numbers meaning it's a positioning flight but not sure about other letters...

Hey,

Yeh this happens a lot, even today operating the GSM 402 (BCN-EDI) in the flightdeck they were using Globespan 4 Echo Delta.

Regards,


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