Originally Posted by
vbroucek
This is simply WRONG and is a common source of confusion on FR24. What you see on FR24 as CPA037 is public flight number even though FR24 is calling it callsign. The actual radio callsign used for air traffic control will be different. ICAO does not allow to have two planes with the same call sign in the air!
To demonstrate this further, FR24 will show BA15 as having callsign BAW15. In the reality, the call sign of that flight is usually "speedbird one five"
FR24 does show true callsign in addition to the flight number. They will use ICAO code (e.g. BAW) instead of spelling the airline callsign out (e.g. Speedbird) but the number they show is the real callsign, not just public flight number. For example, this is flight EY154 with the call sign Etihad One Quebec November:
