Aircraft Indentification on FPLAN FORM
 

Does this have to be the registration, or can you insert your own callsign such as "TRO003" and in the notes section put:

REG/GXXXX RMK/CALLSIGN "TRIO THREE"

Or if you want a different calllsign do you have to do it officially through the CAA?

If you want your own callsign, then you have to apply to the CAA for one, and also locate an unique three character prefix - unique worldwide, not just the UK. It is this prefix and numeric suffix that then goes on the FPL in box 7, with the REG/ in box 18

I have a suspicion that due to a certain amount of 'vanity' callsigns, this may now be restricted to AOC holders, but for the definitive answer, all I can suggest is the CAA

hth

IFR

The callsign has to be registered with ICAO. It then appears in ICAO Doc 8585.

To register, you need to talk to the Comms Section at Heathrow. Not sure if its AIS or NATS.

Callsigns are issued to Companies/Organisations, not Individuals. You don't need an AOC.

Best continue using the standard reg then! Ahh well