All traffic on the manoeuvring area of an aerodrome and all aircraft flying in the vicinity of an aerodrome.
An aerodrome at which air traffic control service is provided to aerodrome traffic.
An alternate aerodrome to which an aircraft may proceed should it become either impossible or inadvisable to land at the aerodrome of intended landing.
An aerodrome at which an aircraft would be able to land after experiencing an abnormal or emergency condition while en-route.
An aerodrome or a defined area on a structure intended to be used wholly or in part for the arrival, departure and surface movement of helicopters.