Twin terms in aviation

Manoeuvring Area : That part of an aerodrome to be used for the take-off, landing and taxiing of aircraft, excluding aprons.

Movement Area : That part of an aerodrome to be used for the take-off, landing and taxiing of aircraft, consisting of the manoeuvring area and the apron(s).

Decision Height : DH referenced to the threshold elevation.

Decision Altitude : Decision altitude (DA) is referenced to mean sea level

Track : The projection on the earth’s surface of the path of an aircraft, the direction of which path at any point is usually expressed in degrees from North (true, magnetic or grid).

Heading : The direction in which the longitudinal axis of an aircraft is pointed, usually expressed in degrees from North (true, magnetic, compass or grid).

Restricted Area : An airspace of defined dimensions, above the land areas or territorial waters of a State, within which the flight of aircraft is restricted in accordance with certain specified conditions.

Danger Area : An airspace of defined dimensions within which activities dangerous to the flight of aircraft may exist at specified times.

Prohibited Area : An airspace of defined dimensions, above the land areas or territorial waters of a State, within which the flight of aircraft is prohibited
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Transition Layer : The airspace between the transition altitude and the transition level.

Transition Altitude : The altitude at or below which the vertical position of an aircraft is controlled by reference to altitudes.

Transition Level : The lowest flight level available for use above the transition altitude.

Flight Plan : Specified information provided to air traffic services units, relative to an intended flight or portion of a flight of an aircraft.

ATC Clearance : Authorization for an aircraft to proceed under condition specified by an ATC unit

ATC Instruction : Directives issued by ATC for the purpose of requiring a pilot to take a specific action

Control zone : controlled airspace extending upwards from the surface of the earth to a specified upper limit.

Control area : A controlled airspace extending upwards from a specified limit above the earth.

Altitude : The vertical distance of a level, a point or an object considered as a point, measured from mean sea level (MSL).

Level : A generic term relating to the vertical position of an aircraft in flight and meaning variously, height, altitude or flight level.

Flight level : A surface of constant atmospheric pressure, which is related to a specific pressure datum

Take-off alternate : An alternate aerodrome at which an aircraft would be able to land should this become necessary shortly after take-off and it is not possible to use the aerodrome of departure.

En-route alternate : An alternate aerodrome at which an aircraft would be able to land in the event that a diversion becomes necessary while en route.

Destination alternate : An alternate aerodrome at which an aircraft would be able to land should it become either impossible or inadvisable to land at the aerodrome of intended landing.

Strayed aircraft : An aircraft which has deviated significantly from its intended track or which reports that it is lost.

Unidentified aircraft : An aircraft which has been observed or reported to be operating in a given area but whose identity has not been established.

runway incursion. Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle or person on the protected area of a surface designated for the landing and take-off of aircraft.
Cavok :: cloud and visibility ok // wind calm