Originally Posted by
james-ozzie
Is it correct to say their are only 5 clearances? Take off, Land, Cross active runway, Climb to../Descend to..
This would be a gross simplification. In a number of Annexes to and procedures adopted pursuant to the Chicago Convention, the International Civil Aviation Organization defines an air traffic control clearance as the
authorization for an aircraft to proceed under conditions specified by an air traffic control unit.
From the wide nature of this definition it is apparent five categories will not suffice to describe the endless number of different clearances one could think of. A note following the definition alone provides six categories of clearances:
The abbreviated term "clearance" may be prefixed by the words "taxi", "take-off", "departure", "en route", "approach" or "landing" to indicate the particular portion of flight to which the air traffic control clearance relates.
It must be noted, though, that even these six categories do not conclude the list of all possible cases. Off the top of my hat, I could at least find two additional types of clearances. One would be the "start-up clearance" and another one the "oceanic entry clearance", although the latter is an outstanding category in so far as flight in international airspace is concerned.