Air Traffic Control Clearance

Authorization for an aircraft to proceed under conditions specified by an air traffic control unit. (FAA4)

Authorization by an air traffic control authority for an aircraft to proceed under specified conditions. 1/2/73

Autorisation accordée à un aéronef de manoeuvrer dans les conditions spécifiées par un organe du contrôle de la circulation aérienne. 1/2/73

[ICAO]
Authorization for an aircraft to proceed under conditions specified by an air traffic control unit.

Note 1: For convenience, the term air traffic control clearance is frequently abbreviated to clearance when used in appropriate contexts.
Note 2: The abbreviated term clearance may be prefixed by the words taxi, takeoff, departure, en route, approach or landing to indicate the particular portion of flight to which the air traffic control clearance relates.