Folks,
Don’t get too wound up about the “legal” bit, or “state” aircraft, a callsign is words/numbers on a flightplan. Think generic.
As for “type”, years back now, but several “well known” operators with G- rego., operated “BAC111” and “DC-9” with some remarkable performance, 189 seats, 10h endurance at M 0.81, did wonders for the overflight charges.
I would wager it still happens around Africa.
I’ve changed callsigns in flight, on G-,N- , P2 and VH aircraft, for all sorts of different reason, some honourable, some just a little dodgy but practical. And none of them had a MTOW under 150T.
For years, ANSETT ferried aircraft on a QANTAS flight number, as did some smaller Australian operators, made life easy for everybody, nice and familiar, and as ARINC didn’t charge shareholder per flight, it just showed up as QF special, no comms. charges. The smallest QF XXX to cross the Pacific, to my knowledge, was a Piper Comanche 260B, owned by a bunch of QF staff.
Probably 10 years ago now, but a QF10Y, (Yankee as in yesterday, the usual QF callsign for a delayed service) was forced to land in Karachi, due the Pakistani’s not believing it really was yesterday’s, running 26 hours late, 2 h behind that day’s aircraft.
Don’t take it all so seriously, remember all the legit. airlines CIA used to "own”, the CIA proprietary’s, probably one or two still around ----- Any guesses in Florida. In Yarpiestan ?
As for “state” aircraft, do you always really know what “Ascot” is ?? Do you know it is only one aircraft ??
Tootle pip!!