Bit of a long shot but the German airline Sudflug (taken over by Condorflug in 1968), IATA prefix SZ, I remember someone many years ago giving me "Bluebird" as their callsign, although I've never managed to confirm this. The logo on the tail, which at first sight I thought was meant to represent a clock, is probably meant to be a blue bird, so the callsign may be correct. Anyone confirm?
