I heard several flights the other day who were adding a letter suffix to their flight number -- such as "X-Ray" (was AF), and one even had two "Yankee Zulu" (was Speedbird-BA)

What is the significance?

MX-5 wrote: ↑Fri Dec 13, 2024 9:16 am I heard several flights the other day who were adding a letter suffix to their flight number -- such as "X-Ray" (was AF), and one even had two "Yankee Zulu" (was Speedbird-BA)

What is the significance?

It cuts down on like or similar sounding call signs. Instead of AF123 and BA123 which when busy can be a real issue, you have AF123X and BA123YZ. Far less chance of one taking the others instruction etc.

It cuts down on like or similar sounding call signs. Instead of AF123 and BA123 which when busy can be a real issue, you have AF123X and BA123YZ. Far less chance of one taking the others instruction etc.

So they would be assigned this suffix enroute? Or when filing the flight plan?

Busy dense airspace with lots of airlines. The ident is given to you in your flight plan. My favourite I have heard so far has been TOM4BJ.