My question only refers to the ATC-clearance given by the tower before or at start-up. "Cleared to xxxx via flightplanroute, xxx-departure squawk xxxx" Is there a requirement to confirm "readback correct" or has this just become a practice?
I know some countries the ATCO would reply with the callsign after a readback to confirm the readback:
ATCO: SIA121 climb FL310
SIA121: Climbing FL310
ATCO: SIA121
(but this is not what Im referring to..)
See, everytime I issue a clearance before departure, the pilot would reply: "cleared to EGLL FPL-route etc", BUT if I then dont use the phrase "readback correct", the pilot would say "confirm readback correct"!
Me confused..