ChrisNH From United States of America, joined Jun 1999, 3920 posts, RR: 2 Reply 1, posted (9 years 2 months 3 weeks 5 days 20 hours ago) and read 1452 times:
I've seen this too, and I think someone once explained that it is because there is another 'flight 51' that departs LHR around the same time this one does, and it's a way for ATC to keep these two flights distinguished from each other. I have no idea whether this is true or not, but if so I have to wonder why BA just doesn't re-number the flight. Or, why the flight doesn't revert back to 'flight 51' once it gets out over the ocean. As for the aircraft, I think it toggles between a 747-400 in the high season and a 777 in the low season.
Ka From Switzerland, joined Apr 2000, 650 posts, RR: 11 Reply 3, posted (9 years 2 months 3 weeks 5 days 12 hours ago) and read 1376 times:
Actually number-letter combinations are very common in ATC especially in Europe. It has been implemented to avoid callsign confusion.
LH, OS, OK, LX,... are using a system of airlinecode (ICAO - three letters) + 1 or 2 numbers + 2 letters. These combinations have nothing to do with the flightnumber printed on the ticket.
on the ticket: LH3725
in ATC: DLH4WR
Speaking from my experience in ATC confusion with similar callsigns has been reduced dramatically after implementation of this system although many ATCOs and pilots were very sceptical in the beginning.
LHR27C From United Kingdom, joined Aug 2004, 1279 posts, RR: 17 Reply 6, posted (9 years 2 months 3 weeks 5 days 7 hours ago) and read 1214 times:
It is quite common, especially with LH and BA. Departing from CPT last year we were following the LHR-bound BA 744, whose callsign was Speedbird Five Eight Juliet. I think it is for ATC identification purposes.
Once you have tasted flight, you will walk the earth with your eyes turned forever skyward
ChrisNH From United States of America, joined Jun 1999, 3920 posts, RR: 2 Reply 8, posted (9 years 2 months 3 weeks 5 days 5 hours ago) and read 1139 times:
OK, I guess we've pretty much agreed that this is done to avoid confusion with ATC. But it puzzles me why that is a better solution than simply renumbering the flight?? ATC could STILL get confused if the 'G' in the callsign is stepped on during a transmission. Oh well...there's gotta be some good reason.
Skymonster From , joined Dec 1969, posts, RR: Reply 9, posted (9 years 2 months 3 weeks 5 days 5 hours ago) and read 1133 times:
When I worked at British Midland (and BA were no different), we used to have BD1, BD51, BD81, BD101, BD121, BD221, BD581, BD771, etc, etc all inbound to LHR first thing in the morning. From a commercial point of view it was and still is important to maintain the concept that the first flights into LHR each day ended in a 1, and the next ended with a 3, then a 5, 7, etc. So the GLA-LHRs were BD1, BD3, BD5, BD7, etc whilst AMS-LHR were BD101, BD103, BD105, etc (the outbound flights had even numbers such as BD2, BD4, etc). Having this flight numbering framework makes it easy for the passengers to understand what flights they want, whether they travel on the same route all the time, or on different routes.
Operationally of course, having all these flight call signs ending with a 1 ("Midland one", "Midland 81", "Midland 101" etc) decending into LHR at roughly the same time caused problems, confusion and on more than one occasion misinterpretted instructions. So, operationally a lot of flights had their call signs changed / renumbered (including letters) to remove all chance of confusion, whilst the commercial flight numbers that passengers use remain as they always were.
Skymonster From , joined Dec 1969, posts, RR: Reply 10, posted (9 years 2 months 3 weeks 5 days 5 hours ago) and read 1121 times:
some airlines use G and other letters to identify non-passenger services - ferry flights if you will
Not usually... Ferry call signs often end with Papa, and flight numbering convention states that non-rev flights should have four digit flight numbers starting with the number 9 (e.g. 9543). Some airlines using the digit after the 9 to designate the purpose of the ferry flight - training, positioning, engineering test flight, etc.