highpeaklad
Posts: 510
Joined: Tue Aug 24, 2004 5:19 am

Why Have A Different Flight Number And Call Sign?

Mon May 22, 2006 6:04 am

Last year I flew SFO - ORD the day before thanksgiving. I cant remember the exact flight number , I'll call it UA850. According to the UA website that flight number continued onto somewhere in south america ?Sao Paolo, but this involved a change of aircraft (747 - 767), so whats the point of having the same flight number?

Sticking to the thread title, I was listening to channel 9 while on the ground and at no point heard mention of UA850. It was only when I heard UA1515 (again I can't remember exactly) cleared for take off and our engines spooled up that I realised we had a different call sign to our flight number. What's the point of this, does it not lead to confusion with tower/ground crew communication?

Any thoughts.

Chris
Don't try to keep up with the Joneses - bring them down to your level !
 
SPREE34
Posts: 1574
Joined: Tue Jun 29, 2004 6:09 am

RE: Why Have A Different Flight Number And Call Sign?

Mon May 22, 2006 8:36 am

The UA850 flight may still have been operating late, or in some sort of equipment swap on the previous leg. Using UA1515 as the callsign prevents any confusion in the ATC system. Carriers will sometimes add one digit, or an alphabetic character as well.

A couple of the Ops types in here probably have some good input for this one.
I don't understand everything I don't know about this.
 
planesarecool
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Joined: Sun Nov 11, 2001 12:37 am

RE: Why Have A Different Flight Number And Call Sign?

Mon May 22, 2006 8:44 am

This isn't really uncommon, even here in the UK.

For example, BD595 from Manchester to Heathrow would be shown as BD595 to passengers, but to ATC it would be BMA3PK. BA also do the same on their short haul (mainly domestic) flights, for example BA1407 (MAN-LHR) would be SHT2W to ATC. I have no idea why though.
 
bohica
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RE: Why Have A Different Flight Number And Call Sign?

Mon May 22, 2006 11:40 am

UA has quite a few flight numbers which has a domestic leg and an international leg with a change of aircraft at the gateway city. Usually the domestic leg uses an 8000 series flight number with ATC to avoid any confusion with the international leg.
 
star_world
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RE: Why Have A Different Flight Number And Call Sign?

Mon May 22, 2006 12:05 pm

There are two main instances of this - the first is the one mentioned by Bohica above, where the flight may be the first leg of a multi-leg route. If there is an equipment change at the international segment then very often a different callsign will be used on the domestic one - there's no guarantee that the international leg will wait for the inbound domestic leg, so it's possible that both could be in the air at the same time. I've seen this happen many times in the past with United.

The second instance is the one commonly seen in Europe, where a flight will be assigned a seemingly random callsign often consisting of letters and numbers. This is done because of the large number of airlines who have very similar flight numbers, both within their own airline and between others. For example, there could easily be BA 954, BA 994, BD 594, AF 1594, etc. all within the same airspace and it would be very easy for the flight crew on one of the flights to mis-hear a callsign. Having random numbers and letters makes each one sound more unique.
 
Carpethead
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Joined: Mon Aug 02, 2004 8:15 pm

RE: Why Have A Different Flight Number And Call Sign?

Mon May 22, 2006 12:26 pm

Quoting Star_world (Reply 4):

Does it even have to be random? Why not use one or two digits from the flight number and the two letters on the aircraft reg that is being flown.
 
flyingfool
Posts: 322
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RE: Why Have A Different Flight Number And Call Sign?

Mon May 22, 2006 10:13 pm

Quoting Planesarecool (Reply 2):
This isn't really uncommon, even here in the UK.

For example, BD595 from Manchester to Heathrow would be shown as BD595 to passengers, but to ATC it would be BMA3PK. BA also do the same on their short haul (mainly domestic) flights, for example BA1407 (MAN-LHR) would be SHT2W to ATC. I have no idea why though.

BA domestic flights as mentioned above even use a total difference "airline name" with the callsign.
Normaly the flights shown on the radar with BAW will be called with "Speedbird" and if the flight has SHT it will be called with "Shuttle"  Smile
 
David_itl
Posts: 5992
Joined: Wed Jun 27, 2001 7:39 am

RE: Why Have A Different Flight Number And Call Sign?

Tue May 23, 2006 6:00 am

Quoting Star_world (Reply 4):
Having random numbers and letters makes each one sound more unique.

You'd have thought some kind of planning would ensure that...however, Air Southwest when they began their NQY-CWL-MAN service had a "clever" idea.

The existing WO307 uses WOW37M going MAN-BRS-PLH. The MAN-CWL-NQY service is WO517 and, for some peculiar reason decided to have that use the callsign of WOW57M. And of course, both services are scheduled to leave within a short space of time - 1st day of operation saw ATC mention that pilots should call WO ops about the confusion - thankfully, they now use WOW5MC for the WO517.

Quoting Planesarecool (Reply 2):
for example BA1407 (MAN-LHR) would be SHT2W to ATC. I have no idea why though.

Minor quibble - it'd be SHT3Y for BA1407 or BA1408 for SHT2W.

David
 
ckfred
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RE: Why Have A Different Flight Number And Call Sign?

Tue May 23, 2006 2:49 pm

Several years ago, I was flying AA from ORD to ATL. The flight originated in PVD, but everything from PHL to BOS was running late, due to snow.

Since there were only a couple of passengers who were flying PVD-ATL, and the crew was present, AA took the next plane from PHX, scheduled to go on to DCA, and sent it to ATL.

We took off about 30 minutes before the plane from PVD was due in. From what a friend of mine who flies for AA tells me, our flight would have had the same call sign, American, but with a different flight number.

I don't remember exactly, but if the flight number were 567 or 1567, the new number would have been 8567. I know that AA flight number in the 9000s are either charters or ferry flights, whereas 8000s mean that a second or third leg of a flight is in the air at the same time as the prior leg.
 
FlyDeltaJets
Posts: 1635
Joined: Thu Feb 02, 2006 4:24 pm

RE: Why Have A Different Flight Number And Call Sign?

Tue May 23, 2006 2:53 pm

At DL we will stubb a flight when it is running into another flight's time. This is esp true with the 112 as that is the flight number from JFK to DUB to SNN and back to JFK. That process relies on everything on time.
The only valid opinions are those based in facts
 
superhub
Posts: 398
Joined: Sat Jan 21, 2006 4:17 pm

RE: Why Have A Different Flight Number And Call Si

Tue May 23, 2006 2:57 pm

Quoting Highpeaklad (Thread starter):
Last year I flew SFO - ORD the day before thanksgiving. I cant remember the exact flight number , I'll call it UA850. According to the UA website that flight number continued onto somewhere in south america ?Sao Paolo, but this involved a change of aircraft (747 - 767), so whats the point of having the same flight number?

To market it as a Direct flight (as opposed to a non-stop flight). Airlines usually do this when there are no non-stop options between two cities...like SFO to Sao Paulo. People who want to fly from SFO to Sao Paulo is more likely to choose your UA850 than other airlines because it seems like everything is streamlined for them.

[Edited 2006-05-23 07:58:53]
 
Mir
Posts: 19108
Joined: Mon Jan 05, 2004 3:55 am

RE: Why Have A Different Flight Number And Call Sign?

Tue May 23, 2006 3:41 pm

When UA has an international flight that uses the same number as a domestic flight, and there is an aircraft change, the domestic flight will get an 81xx flight number on the ATC side of things. This is so that should the first flight of the two get delayed, they can still send out the second flight on time without having two aircraft with the same callsign in the air at the same time (obviously not good).

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
oly720man
Posts: 5760
Joined: Fri May 21, 2004 7:13 am

RE: Why Have A Different Flight Number And Call Sign?

Tue May 23, 2006 6:07 pm

Quoting Highpeaklad (Thread starter):
Last year I flew SFO - ORD the day before thanksgiving. I cant remember the exact flight number , I'll call it UA850. According to the UA website that flight number continued onto somewhere in south america ?Sao Paolo, but this involved a change of aircraft (747 - 767), so whats the point of having the same flight number?

US Airways have US196/197 as LAX-PHL-MAN-PHL-LAX with A320/A321 on the domestic leg and A333 across the water. It used to be a MCO-PHL-MAN service.

Why the same flight number? Why not? Though having said that, how are route licences defined? I presume a flight number covering a number of stages does not constitute a route licence for the whole route, so US can't say, for example, that it flies LAX-MAN because there's an en-route change of aircraft.
I can imagine it annoys PAX that you have to change planes en route even thought the number's the same.
wheat and dairy can screw up your brain
 
User avatar
RobK
Posts: 3249
Joined: Mon Sep 06, 2004 1:43 pm

RE: Why Have A Different Flight Number And Call Sign?

Tue May 23, 2006 6:09 pm

Quoting Carpethead (Reply 5):
Does it even have to be random? Why not use one or two digits from the flight number and the two letters on the aircraft reg that is being flown.

The reg can't be used for part of the trip number because most scheduled airlines file repeat flight plans based on the same ARCID (aircraft identity). If reg's were part of the callsign then this would not be possible as the callsign would be different each time a different aircraft was used.

For many airlines where there's a chance of two of the same flight being in the air at the same time, the suffix 'A' is often used. Northwest seem to use 'N' for reasons not known to me, ie. NWA53N.

R
 
HPLASOps
Posts: 1767
Joined: Thu Nov 24, 2005 6:13 pm

RE: Why Have A Different Flight Number And Call Sign?

Tue May 23, 2006 6:16 pm

Quoting Oly720man (Reply 12):
US Airways have US196/197 as LAX-PHL-MAN-PHL-LAX with A320/A321 on the domestic leg and A333 across the water. It used to be a MCO-PHL-MAN service.

Same thing is true with US 98 LAS-PHL-LGW. LAS-PHL is with a 757 and PHL-LGW is with an A330.
"Just because I know how to get off a freeway doesn't mean I know how to get back on!" - Retard Joe
 
LVTMB
Posts: 293
Joined: Wed Oct 20, 2004 10:18 am

RE: Why Have A Different Flight Number And Call Sign?

Wed May 24, 2006 2:06 am

Quoting Mir (Reply 11):
When UA has an international flight that uses the same number as a domestic flight, and there is an aircraft change, the domestic flight will get an 81xx flight number on the ATC side of things. This is so that should the first flight of the two get delayed, they can still send out the second flight on time without having two aircraft with the same callsign in the air at the same time (obviously not good

True. The only airline I know has this practice is UA. And just as stated above, they only do it with flights that have domestic and international legs. You will not see it on purely domestic flights.

MB

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