GM1 Annex IV (Part-ATS)

GENERAL

In the context of the AMC and GM to Part-ATS, the terms listed below have the following meaning:

—      'accepting air traffic controller (ATCO)’ refers to the air traffic controller next to take control of an aircraft;

—      'accepting control unit’ refers to the air traffic control unit next to take control of an aircraft;

—      ‘advisory airspace’ refers to an airspace of defined dimensions, or designated route, within which air traffic advisory service is available;

—      ‘advisory route’ refers to a designated route along which air traffic advisory service is available;

—      ‘airborne collision avoidance system (ACAS)’ refers to an aircraft system based on secondary surveillance radar (SSR) transponder signals which operates independently of ground-based equipment to provide advice to the pilot on potential conflicting aircraft that are equipped with SSR transponders;

—      ‘aircraft address’ refers to a unique combination of 24 bits available for assignment to an aircraft for the purpose of air-ground communications, navigation and surveillance;  

—      ‘air-taxiing’ refers to the movement of a helicopter/vertical take-off and landing (VTOL) aircraft above the surface of an aerodrome, normally in ground effect and at a ground speed normally less than 37 km/h (20 kt). The actual height may vary, and some helicopters may require air-taxiing above 8 m (25 ft) above ground level (AGL) to reduce ground effect turbulence or provide clearance for cargo slingloads;

—      ‘air traffic’ refers to all aircraft in flight or operating on the manoeuvring area of an aerodrome;

—      ‘approach sequence’ refers to the order in which two or more aircraft are cleared to approach to land at the aerodrome;

—      ‘base turn’ refers to a turn executed by the aircraft during the initial approach between the end of the outbound track and the beginning of the intermediate or final approach track. The tracks are not reciprocal. Base turns may be designated as being made either in level flight or while descending, according to the circumstances of each individual procedure;

—      ‘change-over point’ refers to the point at which an aircraft navigating on an ATS route segment defined by reference to very high-frequency omnidirectional radio ranges is expected to transfer its primary navigational reference from the facility behind the aircraft to the next facility ahead of the aircraft. Change-over points are established to provide the optimum balance in respect of signal strength and quality between facilities at all levels to be used and to ensure a common source of azimuth guidance for all aircraft operating along the same portion of a route segment;

—      ‘common point’ refers to a point on the surface of the earth common to the tracks of two aircraft, used as a basis for the application of separation (e.g. significant point, waypoint, navigation aid, fix);

—      ‘controller-pilot’ refers to in different contexts the interaction between air traffic controllers and pilots;

—      ‘cruise climb’ refers to an aeroplane cruising technique resulting in a net increase in altitude as the aeroplane mass decreases;

—      ‘decision altitude (DA) or decision height (DH)’ refers to a specified altitude or height in a 3D instrument approach operation at which a missed approach must be initiated if the required visual reference to continue the approach has not been established. DA is referenced to mean sea level, and DH is referenced to the threshold elevation. The required visual reference is that section of the visual aids or of the approach area which should have been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position, in relation to the desired flight path. In Category III operations with a DH, the required visual reference is that specified for the particular procedure and operation;

—      ‘discrete code’ refers to a four-digit SSR code with the last two digits not being ‘00’;

—      ‘emergency phase’ refers to a generic term meaning, as the case may be, uncertainty phase, alert phase or distress phase;

—      ‘estimated elapsed time’ refers to the estimated time required to proceed from one significant point to another;

—      ‘expected approach time’ refers to the time at which air traffic control (ATC) expects that an arriving aircraft, following a delay, will leave the holding fix to complete its approach for a landing. The actual time of leaving the holding fix will depend upon the approach clearance;

—      ‘filed flight plan’ refers to the flight plan as filed with an air traffic services unit by the pilot or a designated representative, without any subsequent changes. When the word ‘message’ is used as a suffix to this term, it denotes the content and format of the filed flight plan data as transmitted;

—      ‘flight path monitoring’ refers to the use of ATS surveillance systems for the purpose of providing aircraft with information and advice relative to significant deviations from nominal flight path, including deviations from the terms of their ATC clearances;

—      ‘ground effect’ refers to a condition of improved performance (lift) due to the interference of the surface with the airflow pattern of the rotor system when a helicopter or other VTOL aircraft is operating near the ground. Rotor efficiency is increased by ground effect to a height of about one rotor diameter for most helicopters;

—      ‘initial approach segment’ refers to that segment of an instrument approach procedure between the initial approach fix and the intermediate approach fix or, where applicable, the final approach fix or point;

—      ‘landing area’ refers to that part of a movement area intended for the landing or take-off of aircraft;

—      ‘minimum fuel’ is a term to be used to describe a situation in which an aircraft’s fuel supply has reached a state where the flight is committed to land at a specific aerodrome and no additional delay can be accepted;

—      ‘multilateration (MLAT) system’ refers to a group of equipment configured to provide position derived from the SSR transponder signals (replies or squitters) primarily using time difference of arrival (TDOA) techniques. Additional information, including identification, can be extracted from the received signals);

—      ‘normal operating zone (NOZ)’ refers to airspace of defined dimensions extending to either side of a published instrument approach procedure final approach course or track. Only that half of the NOZ adjacent to a no transgression zone (NTZ) is taken into account in independent parallel approaches;

—      ‘no transgression zone (NTZ)’ refers to, in the context of independent parallel approaches, a corridor of airspace of defined dimensions located centrally between the two extended runway centre lines, where a penetration by an aircraft requires an air traffic controller intervention to manoeuvre any threatened aircraft on the adjacent approach;

—      ‘obstacle clearance altitude (OCA)’ refers to the lowest altitude above the elevation of the relevant runway threshold or the aerodrome elevation as applicable, used in establishing compliance with appropriate obstacle clearance criteria. The OCA is referenced to mean sea level;

—      ‘obstacle clearance height (OCH)’ refers to the lowest height above the elevation of the relevant runway threshold or the aerodrome elevation as applicable, used in establishing compliance with appropriate obstacle clearance criteria. OCH is referenced to the threshold elevation or in the case of non-precision approach procedures to the aerodrome elevation or the threshold elevation if that is more than 2 m (7 ft) below the aerodrome elevation. An OCH for a circling approach procedure is referenced to the aerodrome elevation;

—      ‘onward clearance time’ refers to the time at which an aircraft can expect to leave the fix at which it is being held;

—      ‘procedural ATC service’ refers to a term that is used to indicate that information derived from an ATS surveillance system is not required for the provision of air traffic control service;

—      ‘procedural separation’ refers to the separation used when providing the procedural air traffic control service;

—      ’procedure turn’ refers to a manoeuvre in which a turn is made away from a designated track followed by a turn in the opposite direction to permit the aircraft to intercept and proceed along the reciprocal of the designated track. Procedure turns are designated ‘left’ or ‘right’ according to the direction of the initial turn. Procedure turns may be designated as being made either in level flight or while descending, according to the circumstances of each individual procedure;

—      ‘PSR blip’ refers to the visual indication, in a non-symbolic form, on a situation display, of the position of an aircraft obtained by primary radar;

—      ‘radar approach’ refers to an approach in which the final approach phase is executed under the direction of an air traffic controller using radar;

—      ‘radar clutter’ refers to the visual indication, on a situation display, of unwanted signals;

—      ‘radar contact’ refers to the situation which exists when the radar position of a particular aircraft is seen and identified on a situation display;

—      ‘reporting point’ refers to a specified geographical location in relation to which the position of an aircraft can be reported;

—      ‘runway-holding position’ refers to a designated position intended to protect a runway, an obstacle limitation surface, or an instrument landing system (ILS)/microwave landing system (MLS) critical/sensitive area at which taxiing aircraft and vehicles shall stop and hold unless otherwise authorised by the aerodrome control tower. In radiotelephony phraseologies, the expression ‘holding point’ is used to designate the runway-holding position;

—      ‘runway incursion’ refers to 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;

—      ‘runway strip’ refers to a defined area including the runway and stopway, if provided, intended to:

(a)      reduce the risk of damage to aircraft running off a runway; and

(b)      protect aircraft flying over it during take-off or landing operations;

—      ‘segregated parallel operations’ refers to simultaneous operations on parallel or near-parallel instrument runways in which one runway is used exclusively for approaches and the other runway is used exclusively for departures;

—      ‘SSR response’ refers to the visual indication, in a non-symbolic form, on a situation display, of a response from an SSR transponder in reply to an interrogation;

—      ‘stopway’ refers to a defined rectangular area on the ground at the end of take-off run available, prepared as a suitable area in which an aircraft can be stopped in the case of an abandoned take-off;

—      ‘total estimated elapsed time’ refers to, for IFR flights, the estimated time required from take-off to arrive over that designated point, defined by reference to navigation aids, from which it is intended that an instrument approach procedure will be commenced, or, if no navigation aid is associated with the destination aerodrome, to arrive over the destination aerodrome. For VFR flights, it refers to the estimated time required from take-off to arrive over the destination aerodrome;

—      ‘touchdown’ refers to the point where the nominal glide path intercepts the runway. ‘Touchdown’ as defined above is only a datum and is not necessarily the actual point at which the aircraft will touch the runway;

—      ‘touchdown zone’ refers to the portion of a runway, beyond the threshold, intended as the first point of contact between landing aircraft and the runway;

—      ‘visual surveillance system’ refers to an electro-optical system providing an electronic visual presentation of traffic and any other information necessary to maintain situational awareness at an aerodrome and its vicinity.