krisyyz
Topic Author
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Joined: Thu Nov 25, 2004 11:04 pm

Why Two Different Flight #s For The Same Flight?

Thu Dec 30, 2010 12:29 am

Sorry to ask such a basic question here but I would really like to know why KLM flight 692 left as KLM 32 today.

My mother departed KL 692 yet when I was listening to ATC I heard the KLM flight depart as “KL 32 heavy”. Why are there two flight numbers? Is this a routine occurrence or are there other factors that may change a flights callsign? Is it only KLM that does this ?


Most flight tracking websites like Flightaware and flightview have both KL 692 and KL 32 listed but only KL 32 as “departed”.



Any insight is greatly appreciated.

KrisYYZ

[Edited 2010-12-29 16:32:18]
 
SB
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RE: Why Two Different Flight #s For The Same Flight?

Thu Dec 30, 2010 1:29 am

The ATC callsign is sometimes different from the commercial flight number for operational reasons - usually to avoid having similar callsigns on the same frequency at the same time (KLM692 and 926 for example).

The ATC callsign can also contain letters, for example BA92 which operates YYZ-LHR used to file as BAW7CA for a while. Substitutions are most common in Europe.

S.
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Mir
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RE: Why Two Different Flight #s For The Same Flight?

Thu Dec 30, 2010 1:44 am

Quoting SB (Reply 1):
The ATC callsign is sometimes different from the commercial flight number for operational reasons - usually to avoid having similar callsigns on the same frequency at the same time (KLM692 and 926 for example).

Or another airline's flight 692.

-Mir
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IAHFLYR
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RE: Why Two Different Flight #s For The Same Flight?

Thu Dec 30, 2010 5:44 am

Quoting Mir (Reply 2):
Or another airline's flight 692



More often it is only when another flight for the same airline is in the air, regardless of where the flights are located. There are many instances of the same flight number operating with different airlines. It then is something ATC should alert both operators of the similar sounding call signs on the same frequency.
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Mir
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RE: Why Two Different Flight #s For The Same Flight?

Thu Dec 30, 2010 5:53 am

Quoting IAHFLYR (Reply 3):
There are many instances of the same flight number operating with different airlines. It then is something ATC should alert both operators of the similar sounding call signs on the same frequency.

Air India 111 and Aer Lingus 111 used to arrive at JFK right about the same time. They changed it after a while so that Air India 111 and Aer Lingus 11C arrived at about the same time (obviously, Aer Lingus uses "Shamrock" for their callsign).

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
IAHFLYR
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RE: Why Two Different Flight #s For The Same Flight?

Thu Dec 30, 2010 6:08 am

[quote=Mir,reply=4]Air India 111 and Aer Lingus 111 used to arrive at JFK right about the same time. They changed it after a while so that Air India 111 and Aer Lingus 11C arrived at about the same time (obviously, Aer Lingus uses "Shamrock" for their callsign).[/quote

Exactly.

The call sign of the individual operator doesn't matter, regardless of Southwest 7 and Continental 7 both on the same frequency at the same time, it is a similar sounding call sign which needs to be brought to the attention of the flight crew. If both landing at the same airport as you mention in the JFK situation, then yes somebody needs to change the flight number to avoid any possible confusion. Toss in the mix different states the flights come from and there is even more of a reason to fix any issues.
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jwenting
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RE: Why Two Different Flight #s For The Same Flight?

Thu Dec 30, 2010 7:20 am

Or ATC can assign different numbers to different legs of the same flight.
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krisyyz
Topic Author
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RE: Why Two Different Flight #s For The Same Flight?

Thu Dec 30, 2010 2:00 pm

Thank you everybody for answering my question.

KrisYYZ

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