KCAA ATC key terms

A service provided to prevent collisions between aircraft and between aircraft and obstructions on the manoeuvring area, and to expedite and maintain an orderly flow of traffic.

An authorisation for an aircraft to proceed under conditions specified by an air traffic control unit, communicated to the pilot and acknowledged before the aircraft acts on it.

The spacing maintained between aircraft, or between an aircraft and terrain or obstacles, by vertical, lateral, longitudinal or radar means to reduce the risk of collision.

Spacing achieved by assigning aircraft different levels, expressed as a minimum height gap, normally 1,000 feet, or 2,000 feet above a specified transition altitude.

Spacing between aircraft on the same route, level or track, achieved by time intervals, distance along track, or position reporting, so that following aircraft stay behind preceding ones.

Spacing achieved by keeping aircraft on different routes, tracks or geographical areas, or by requiring one aircraft to remain a set distance from a defined line or point.

A pilot's repetition of safety-related parts of an ATC instruction or clearance, which the controller must verify, correcting any discrepancy before the aircraft acts on it.

A surface of constant atmospheric pressure related to a standard datum of 1,013.2 hectopascals, shown as three digits, used above the transition altitude for vertical separation.

The altitude at or below which an aircraft's altitude is controlled by reference to the altimeter set to local pressure; above it, flight levels are used.

A predetermined manoeuvre keeping an aircraft within a specified airspace while awaiting further clearance, flown as a racetrack with specified inbound track, turn direction and leg timing or distance.

An ATC unit established to provide approach control service to controlled flights arriving at, departing from or transiting the terminal area around one or more aerodromes.

An ATC unit providing aerodrome control service, issuing information and clearances to aircraft on the manoeuvring area and in the traffic circuit to prevent collisions and maintain orderly flow.

An ATC unit providing area control service to controlled flights in control areas under its jurisdiction, usually en route and away from the immediate vicinity of aerodromes.

A controlled airspace extending upwards from a specified limit above the earth, within which air traffic control service is provided to controlled flights.

The part of an aerodrome used for the take-off, landing and taxiing of aircraft, excluding aprons, where aerodrome control protects aircraft and vehicles from collision.

Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle or person on the protected area of a surface designated for landing and take-off.

A surveillance system that interrogates aircraft transponders and uses the replies to determine position, identity and altitude, providing more information than primary radar alone.

Radar that detects aircraft by reflecting radio energy from the aircraft's surfaces, giving position without requiring any equipment on board, but usually no identity or altitude.

Separation between aircraft established by reference to radar-derived positions, applying specified minimum horizontal and vertical distances instead of procedural separation methods.

The altitude-reporting function of an aircraft transponder, replying to interrogation with pressure altitude so controllers can see and verify the aircraft's level.

A selective secondary surveillance radar mode that addresses individual aircraft, allowing discrete identity, altitude and data-link exchange with reduced interference and greater capability.

A four-digit octal code set on an aircraft's transponder to identify it on secondary surveillance radar and to support identification and separation by the controller.

A surveillance technique in which aircraft automatically transmit position and other data derived from on-board systems, used by ATC without ground radar interrogation.

A data-link service allowing controllers and pilots to exchange clearances and messages as text rather than voice, reducing read-back errors and channel congestion.

The process by which a controller determines that a particular radar position symbol corresponds to a specific aircraft, using procedures such as position reports or turn instructions.

A warning issued by a controller to an aircraft found to be in unsafe proximity to terrain, obstructions or other aircraft, indicating the hazard and, if time permits, a suggested avoidance action.

A service using available personnel and equipment to find persons in distress and provide aid, coordinated by a rescue coordination centre within a designated search and rescue region.

A unit responsible for promoting efficient organisation of search and rescue services and for coordinating the conduct of search and rescue operations within a search and rescue region.

An area of defined dimensions associated with a rescue coordination centre within which search and rescue services are provided, often matching or complementing a flight information region.

A condition of being threatened by serious and imminent danger requiring immediate assistance, signalled by MAYDAY and triggering priority handling and search and rescue action.

A condition concerning the safety of an aircraft or person on board but not requiring immediate assistance, signalled by PAN PAN and given priority over routine traffic.

A service provided to notify appropriate organisations regarding aircraft in need of search and rescue aid, and to assist such organisations as required.

A generic term covering uncertainty, alert and distress phases, each defined by the level of concern about an aircraft's safety and triggering progressively stronger response actions.

Emergency locator transmitter carried on aircraft that broadcasts a distress signal on designated frequencies, helping search and rescue locate a crash site.

A publication issued by or with the authority of a state containing aeronautical information of a lasting character essential to air navigation.

A notice distributed by means of telecommunication containing information on the establishment, condition or change of any facility, service or procedure whose timely knowledge is essential to flight operations.

A temporary publication issued to notify changes to information in the Aeronautical Information Publication that cannot be handled by NOTAM because of size or duration.

The Aeronautical Information Regulation and Control system, under which significant changes are published on predetermined effective dates so operators can update documentation in advance.

An airspace of defined dimensions within which flight information service and alerting service are provided, often corresponding to the area of a state's responsibility.