Air Navigation System
The aggregate of organisations, people, infrastructure, equipment, procedures, rules and information used to provide to Airspace Users Air Navigation Services in order to ensure the safety, regularity and efficiency of international air navigation.
Air Route Surveillance Radar
Radar designed to provide surveillance on a long range basis. In primary mode, surveillance is normally to 150 nautical miles from the antenna and secondary mode can extend to distances exceeding 200 nautical miles at high altitudes.
Air Route Traffic Control Centre
Divided into geographic regions, Air Route Traffic Control Centres direct the flow of traffic during the en.route phase of flight. In the planned FANS environment, VHF voice clutter will be reduced in part by the expanded use of data links to transmit special instructions, weather and ATC clearances. Such data will be relayed to the aircraft via the Aeronautical Telecommunications Network (ATN). In high traffic density terminal areas, this will reduce frequency congestion and improve communications with resultant benefits in greater capacity during peak periods and increased safety.
See also Area Control Centre.
Air Traffic
All aircraft in flight or operating on the manoeuvring area of an aerodrome (ICAO).
Air Traffic Advisory Service
A service provided for the purpose of : preventing collisions between aircraft, and on the manoeuvring area between aircraft and obstructions; expediting and maintaining an orderly flow of air traffic.
Air Traffic Control
A service operated by the appropriate authority to promote the safe, orderly and expeditious flow of air traffic.
Air Traffic Control Clearance
Authorisation 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, take-off, departure, en route, approach or landing to indicate the particular portion of flight to which the air traffic control clearance relates.
Air Traffic Control Complexity
The complexity of the ATC environment is assessed by taking into account the volume of air traffic, its complexity and the complexity of the airspace organisation; categories of ATC Complexity used in the CIP context comprise high, medium/low and very low complexity.