Devenition and Abreviation Aeronautical Telecommunication (Alphabet A)

Accident. An occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight until such time as all such persons have disembarked, in which:
a) a person is fatally or seriously injured as a result of:

•  being in the aircraft, or 
• direct contact with any part of the aircraft, including parts which have become detached from the  aircraft, or 
• direct exposure to jet blast,except when the injuries are from natural causes, self-inflicted or inflicted by other persons, or when the injuries are to stowaways hiding outside the areas normally available to the passengers and crew; or

b) The aircraft sustains damage or structural failure which:

• adversely affects the structural strength, performance or flight characteristics of the aircraft, and 
• would normally require major repair or replacement of the affected component, except for engine failure or damage, when the damage is limited to the engine, its cowlings or accessories; or for damage limited to propellers, wing tips, antennas, tires, brakes, fairings, small dents or puncture holes in the aircraft skin; or

c) the aircraft is missing or is completely inaccessible.

Accountable manager mean designed an organization employee. 

Accounting management. An ATN systems management facility to monitor users for use of network resources and to limit the use of those resources. 

Accredited medical conclusion. The conclusion reached by one or more medical experts acceptable to the Licensing Authority for the purposes of the case concerned, in consultation with flight operations or other experts as necessary. 

Accredited representative. A person designated by a State, on the basis of his or her qualifications, for the purpose of participating in an investigation conducted by another State.

Accuracy. A degree of conformance between the estimated or measured value and the true value.

Adviser. A person appointed by a State, on the basis of his or her qualifications, for the purpose of assisting its accredited representative in an investigation. 

Advisory airspace. An airspace of defined dimensions, or designated route, within which air traffic advisory service is available. 

Advisory Circular (AC) means DGCA guidance methods compliance with regulations. 

Advisory route. A designated route along which air traffic advisory service is available. 

Aerial work . An aircraft operation in which an aircraft is used for specialized service such as agriculture, construction, photography, surveying, observation and patrol, search and rescue, aerial advertisement. 

Aerodrome/Airport. A defined area on land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure and surface movement of aircraft. 

Aerodrome / Airport certificate. A certificate issued by the appropriate authority under applicable regulations for the operation of an aerodrome. 

Aerodrome beacon. Aeronautical beacon used to indicate the location of an aerodrome from the air. 

Aerodrome identification sign. A sign placed on an aerodrome to aid in identifying the aerodrome from the air. 

Aerodrome control service. Air traffic control service for aerodrome traffic. 

Aerodrome control tower. A unit established to provide air traffic control service to aerodrome traffic. 

Aerodrome traffic. All traffic on the manoeuvring area of an aerodrome and all aircraft flying in the vicinity of an aerodrome. 

Aerodrome traffic zone. An airspace of defined dimensions established around an aerodrome for the protection of aerodrome traffic. 

Aerodrome operating minima. The limits of usability of an aerodrome for:

a) take-off, expressed in terms of runway visual range and/or visibility and, if necessary, 

    cloud conditions; 

b) landing in precision approach and landing operations, expressed in terms of visibility and/or 

    runway visual range and decision altitude/height (DA/H) 

c) landing in approach and landing operations with vertical guidance, expressed in terms of 

    visibility and/or runway visual range and decision altitude/height (DA/H); and 

d) landing in non-precision approach and landing operations, expressed in terms of visibility 

    and/or runway visual range, minimum descent altitude/height (MDA/H) and, if necessary, 

    cloud conditions. 

Aerodrome climatological summary. Concise summary of specified meteorological elements at an aerodrome, based on statistical data.

Aerodrome climatological table. Table providing statistical data on the observed occurrence of one or more meteorological elements at an aerodrome. 

Aerodrome control tower. A unit established to provide air traffic control service to aerodrome traffic. 

Aerodrome elevation. The elevation of the highest point of the landing area. 

Aerodrome meteorological office. An office, located at an aerodrome, designated to provide meteorological service for international air navigation. 

Aerodrome reference point. The designated geographical location of an aerodrome.
Aerodrome traffic density.
a) Light. Where the number of movements in the mean busy hour is not greater 

    than 15 per runway or typically less than 20 total aerodrome movements. 

b) Medium. Where the number of movements in the mean busy hour is of 

    the order of 16 to 25 per runway or typically between 20 to 35 total aerodrome movements. 

c) Heavy. Where the number of movements in the mean busy hour is of the order 

    of 26 or more per runway or typically more than 35 total aerodrome movements. 

Aerodynamic coefficients means nondimensional coefficients for aerodynamic forces and moments. 

Aeronautical beacon. An aeronautical ground light visible at all azimuths, either continuously or intermittently, to designate a particular point on the surface of the earth. 

Aeronautical chart. A representation of a portion of the earth, its culture and relief, specifically designated to meet the requirements of air navigation. 

Aeronautical data. A representation of aeronautical facts, concepts or instructions in a formalized manner suitable for communication, interpretation or processing. 

Aeronautical fixed circuit. A circuit forming part of the aeronautical fixed service (AFS). 

Aeronautical fixed service (AFS). A telecommunication service between specified fixed points provided primarily for the safety of air navigation and for the regular, efficient and economical operation of air services. 

Aeronautical fixed telecommunication network (AFTN). A worldwide system of aeronautical fixed circuits provided, as part of the aeronautical fixed service, for the exchange of messages and/or digital data between aeronautical fixed stations having the same or compatible communications characteristics. 

Aeronautical fixed telecommunication network circuit. A circuit forming part of the aeronautical fixed telecommunication network (AFTN). 

Aeronautical ground light. Any light specially provided as an aid to air navigation, other than a light displayed on an aircraft.

Aeronautical information. Information resulting from the assembly, analysis and formatting of aeronautical data. 

Aeronautical Information Circular (AIC). A notice containing information that does not qualify for the origination of a NOTAM or for inclusion in the AIP, but which relates to flight safety, air navigation, technical, administrative or legislative matters. 

Aeronautical Information Publication (AIP). A publication issued by or with the authority of a State and containing aeronautical information of a lasting character essential to air navigation. 

AIP Amendment. Permanent changes to the information contained in the AIP. 

AIP Supplement. Temporary changes to the information contained in the AIP which are published by means of special pages. 

Aeronautical information service (AIS). A service established within the defined area of coverage responsible for the provision of aeronautical information/data necessary for the safety, regularity and efficiency of air navigation. 

Application. Manipulation and processing of data in support of user requirements (ISO 19104). 

Assemble. A process of merging data from multiple sources into a database and establishing a baseline for subsequent processing. 

AIS product. Aeronautical information provided in the form of the elements of the Integrated Aeronautical Information Package (except NOTAM and PIB), including aeronautical charts, or in the form of suitable electronic media. 

Aeronautical meteorological station. A station designated to make observations and meteorological reports for use in international air navigation. 

Aeronautical mobile service (RR S1.32). A mobile service between aeronautical stations and aircraft stations, or between aircraft stations, in which survival craft stations may participate; emergency position- indicating radiobeacon stations may also participate in this service on designated distress and emergency frequencies. 

Aeronautical mobile ®* service (RR S1.33). An aeronautical mobile service reserved for communications relating to safety and regularity of flight, primarily along national or international civil air routes. 

Aeronautical mobile-satellite service (RR S1.35). A mobile-satellite service in which mobile earth stations are located on board aircraft; survival craft stations and emergency position-indicating radiobeacon stations may also participate in this service. 

Aeronautical mobile-satellite ®* service (RR S1.36). An aeronautical mobile-satellite service reserved for communications relating to safety and regularity of flights, primarily along national or international civil air routes. 

Aeronautical radio navigation service (RR S1.46). A radio navigation service intended for the benefit and for the safe operation of aircraft.

Aeronautical station. A land station in the aeronautical mobile service. In certain instances, an aeronautical station may be located, for example, on board ship or on a platform at sea. 

Aeronautical telecommunication station. A station in the aeronautical telecommunication service. 

Aeronautical telecommunication service. A telecommunication service provided for any aeronautical purpose. 

Aeronautical telecommunication agency. An agency responsible for operating a station or stations in the aeronautical telecommunication service. 

Aeronautical telecommunication log. A record of the activities of an aeronautical telecommunication station.

Aeronautical telecommunication network (ATN). An internetwork architecture that allows ground, air-ground and avionic data subnetworks to interoperate by adopting common interface services and protocols based on the International Organization for Standardization (ISO) Open Systems Interconnection (OSI) reference model. 

AIDC (ATS interfacility data communication) application. An ATN application dedicated to exchanges between ATS units (ATSUs) of air traffic control (ATC) information in support of flight notification, flight coordination, transfer of control, transfer of communication, transfer of surveillance data and transfer of general data. 

ATN directory services (DIR). A service which provides the capability for an application entity or user in the ATN community to query a distributed directory data base and retrieve addressing, security and technical capabilities information relating to other users or entities within the ATN community. 

ATN security services. A set of information security provisions allowing the receiving end system or intermediate system to unambiguously identify (i.e. authenticate) the source of the received information and to verify the integrity of that information. 

ATN systems management (SM). A collection of facilities to control, coordinate and monitor the resources which allow communications to take place in the ATN environment. These facilities include fault management, accounting management, configuration management, performance management and security management. 

Aeronautical administrative communication (AAC). Communication used by aeronautical operating agencies related to the business aspects of operating their flights and transport services. This communication is used for a variety of purposes, such as flight and ground transportation, bookings, deployment of crew and aircraft or any other logistical purposes that maintain or enhance the efficiency of over-all flight operation. 

Aeronautical operational control in telecommunications. Communication required for the exercise of authority over the initiation, continuation, diversion or termination of flight for safety, regularity and efficiency reasons.

Aeronautical passenger communication (APC). Communication relating to the non-safety voice and data services to passengers and crew members for personal communication. 

AIRAC. An acronym (aeronautical information regulation and control) signifying a system aimed at advance notification based on common effective dates, of circumstances that necessitate significant changes in operating practices. 

Airbase means an area of land and/or water within the territory of the Republic of Indonesia which is used for the aviation activities of the Armed force of the Republic of Indonesia 

Airborne collision avoidance system (ACAS). 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. 

Air carrier means a person who undertakes directly by lease, or other arrangement, to engage in air transportation.

Air Carrier/Air Operator Certificate Holder mean a person who undertakes directly by lease or other arrangements to engage in air transportation. 

Air commerce means interstate, overseas, or foreign air commerce or the transportation of mail by aircraft or any operation or navigation of aircraft within the limits of any airway or any operation or navigation of aircraft which directly affects, or which may endanger safety in, interstate, overseas, or foreign air commerce. 

Aircraft. Any machine that can derive support in the atmosphere from the reactions of the air other than the reactions of the air against the earth’s surface. 

Aircraft address. A unique combination of twenty-four bits available for assignment to an aircraft for the purpose of air-ground communications, navigation and surveillance. 

Aircraft avionics. A term designating any electronic device - including its electrical part for use in an aircraft, including radio, automatic flight control and instrument systems. 

Aircraft - category. Classification of aircraft according to specified basic characteristics, e.g. aeroplane, helicopter, glider, free balloon. 

Aircraft certificated for single-pilot operation. A type of aircraft which the State of Registry has determined, during the certification process, can be operated safely with a minimum crew of one pilot. 

Aircraft classification number (ACN). A number expressing the relative effect of an aircraft on a pavement for a specified standard subgrade category. 

Aircraft earth station (AES). A mobile earth station in the aeronautical mobile-satellite service located on board an aircraft (see also “GES”). 

Aircraft engine means an engine that is used or intended to be used for propelling aircraft. It includes turbosuperchargers, appurtenances, and accessories necessary for its functioning, but does not include propellers.

Aircraft operating agency. The person, organization or enterprise engaged in, or offering to engage in, an aircraft operation. Aircraft operation manual. A manual, acceptable to the State of the Operator, containing normal, abnormal and emergency procedures, checklists, limitations, performance information, details of the aircraft systems and other material relevant to the operation of the aircraft. 

Aircraft observation. The evaluation of one or more meteorological elements made from an aircraft in flight. 

Aircraft stand. A designated area on an apron intended to be used for parking an aircraft. Aircraft - type of. All aircraft of the same basic design including all modifications thereto except those modifications which result in a change in handling or flight characteristics. 

Air defence identification zone (ADIZ). Special designated airspace of defined dimensions within which aircraft are required to comply with special identification and/or reporting procedures additional to those related to the provision of air traffic services (ATS). 

Airframe means the fuselage, booms, nacelles, cowlings, fairings, airfoil surfaces (including rotors but excluding propellers and rotating airfoils of engines), and landing gear of an aircraft and their accessories and controls. 

Air-report. A report from an aircraft in flight prepared in conformity with requirements for position, and operational and/or meteorological reporting. 

Air-ground communication. Two-way communication between aircraft and stations or locations on the surface of the earth. 

Air-to-ground communication. One-way communication from aircraft to stations or locations on the surface of the earth. 

Air-ground control radio station. An aeronautical telecommunication station having primary responsibility for handling communications pertaining to the operation and control of aircraft in a given area.

AIRMET information. Information issued by a meteorological watch office concerning the occurrence or expected occurrence of specified en-route weather phenomena which may affect the safety of low-level aircraft operations and which was not already included in the forecast issued for low-level flights in the flight information region concerned or sub-area thereof. 

Air operator certificate (AOC). A certificate authorizing an operator to carry out specified commercial air transport operation. 

Airplane / Aeroplane. A power-driven heavier-than-air aircraft, deriving its lift in flight chiefly from aerodynamic reactions on surfaces which remain fixed under given conditions of flight.

Airplane reference field length. The minimum field length required for take-off at maximum certificated take-off mass, sea level, standard atmospheric conditions, still air and zero runway slope, as shown in the appropriate aeroplane flight manual prescribed by the certificating authority or equivalent data from the aeroplane manufacturer. 

Field length means balanced field length for aeroplanes, if applicable, or take-off distance in other cases. 

Air-report. A report from an aircraft in flight prepared in conformity with requirements for position, and operational and/ or meteorological reporting. 

Airship means an engine driven lighter-than-air aircraft that can be steered. Airspace means the airspace over the land and water areas of Republic of Indonesia. 

Air-taxiing. Movement of a helicopter/VTOL above the surface of an aerodrome, normally in ground effect and at a ground speed normally less than 37 km/h (20 kt). 

Air taxiway. A defined path on the surface established for the air taxiing of helicopters. 

Air traffic means aircraft operating in the air or on an airport surface, exclusive of loading ramps and parking areas or All aircraft in flight or operating on the manoeuvring area of an aerodrome. 

Air traffic clearance means an authorization by air traffic control, for the purpose of preventing collision between known aircraft, for an aircraft to proceed under specified traffic conditions within controlled airspace. 

Air traffic advisory service. A service provided within advisory airspace to ensure separation, in so far as practical, between aircraft which are operating on IFR flight plans. 

Air traffic control means a service operated by appropriate authority to promote the safe, orderly, and expeditious flow of air traffic. 

Air traffic control clearance. Authorization for an aircraft to proceed under conditions specified by an air traffic control unit. 

Air traffic control service. A service provided for the purpose of:
a) preventing collisions:
    1) between aircraft, and 

    2) on the manoeuvring area between aircraft and obstructions, and
b) expediting and maintaining an orderly flow of air traffic.

Air traffic control unit. A generic term meaning variously, area control centre, approach control unit or aerodrome control tower. 

Air traffic service. A generic term meaning variously, flight information service, alerting service, air traffic advisory service, air traffic control service (area control service, approach control service or aerodrome control service).

Application entity (AE). Part of an application process that is concerned with communication within the OSI environment. The aspects of an application process that need to be taken into account for the purposes of OSI are represented by one or more AEs.

Application information. Refers to the application names (e.g. AE qualifiers such as ADS and CPC), version numbers, and addresses (the long or short TSAP, as required) of each application. 

ATS direct speech circuit. An aeronautical fixed service (AFS) telephone circuit, for direct exchange of information between air traffic services (ATS) units. 

ATSC class. The ATSC class parameter enables the ATSC user to specify the quality of service expected for the offered data. The ATSC class value is specified in terms of ATN end-to-end transit delay at 95 per cent probability. 

ATS communications (ATSC). Communication related to air traffic services including air traffic control, aeronautical and meteorological information, position reporting and services related to safety and regularity of flight. This communication involves one or more air traffic service administrations. This term is used for purposes of address administration. 

ATS interfacility data communication (AIDC). Automated data exchange between air traffic services units, particularly in regard to co-ordination and transfer of flights. 

ATS message handling services (ATSMHS). Procedures used to exchange ATS messages over the ATN such that the conveyance of an ATS message is in general not correlated with the conveyance of another ATS message by the service provider. 

ATS unit (ATSU). A generic term meaning variously, air traffic control unit, flight information centre or air traffic services reporting office. 

Authentication. A process used to ensure the identity of a person/user/network entity. 

Authorized path. A communication path that the administrator(s) of the routing domain(s) has pre-defined as suitable for a given traffic type and category. 

Automatic terminal information service (ATIS). The automatic provision of current, routine information to arriving and departing aircraft throughout 24 hours or a specified portion thereof. 

ATIS application. A FIS application that supports the D-ATIS. 

Air traffic services airspaces. Airspaces of defined dimensions, alphabetically designated, within which specific types of flights may operate and for which air traffic services and rules of operation are specified. 

Air traffic services reporting office. A unit established for the purpose of receiving reports concerning air traffic services and flight plans submitted before departure. 

Air traffic services unit. A generic term meaning variously, air traffic control unit, flight information centre or air traffic services reporting office.

Air Traffic Service (ATS) route is a specified route designated for channeling the flow of traffic as necessary for the provision of air traffic services. The term “ATS route” refers to a variety of airways, including jet routes, area navigation (RNAV) routes, and arrival and departure routes. An ATS route is defined by route specifications, which may include:

(1) An ATS route designator; 

(2) The path to or from significant points; 

(3) Distance between significant points; 

(4) Reporting requirements; and 

(5) The lowest safe altitude determined by the appropriate authority. 

Air transit route. A defined path on the surface established for the air transitting of helicopters. 

Air transport means any activity using an aircraft for carrying passengers, cargo and/or post in one or more trips from one airport to another . 

Air Transportation Service, the operation for remuneration, including positioning flights, of any aircraft, which is listed on the air carrier’s Air operating certificate. 

Airway. A control area or portion thereof established in the form of a corridor. Airworthy. Conform to type design and condition for safe operation. 

Airworthiness Certificate/Certificate of Airworthiness (C of A) means A document issued by a DGCA to an individual aircraft and the aircraft meets the appropriate airworthiness requirements. 

Airworthiness Directive (AD) means the legally enforceable rules that apply to the following products : aircraft, aircraft engines, propellers, and appliances. 

Alert Area. An alert area is established to inform pilots of a specific area wherein a high volume of pilot training or an unusual type of aeronautical activity is conducted. 

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

Alternate aerodrome. An aerodrome to which an aircraft may proceed when it becomes either impossible or inadvisable to proceed to or to land at the aerodrome of intended landing. Alternate aerodromes include the following: 

Alternate airport means an airport at which an aircraft may land if a landing at the intended airport becomes inadvisable. 

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

En-route alternate. An aerodrome at which an aircraft would be able to land after experiencing an abnormal or emergency condition while en route. 

ETOPS en-route alternate. A suitable and appropriate alternate aerodrome at which an aeroplane would be able to land after experiencing an engine shutdown or other abnormal or emergency condition while en route in an ETOPS operation.

    Destination alternate. An alternate aerodrome to which an aircraft may proceed should it become either impossible or inadvisable to land at the aerodrome of intended landing. 

    Adequate Alternate Airport/Aerodrome Is one at which landing performance requirements can be met and has the necessary facilities and services. 

Alternate heliport. A heliport specified in the flight plan to which a flight may proceed when it becomes inadvisable to land at the heliport of intended landing. 

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

Altitude engine means a reciprocating aircraft engine having a rated takeoff power that is producible from sea level to an established higher altitude. 

Ampere (A). The ampere is that constant electric current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 metre apart in vacuum, would produce between these conductors a force equal to 2 × 10-7 newton per metre of length. 

Anticipated operating conditions. Those conditions which are known from experience or which can be reasonably envisaged to occur during the operational life of the aircraft taking into account the operations for which the aircraft is made eligible, the conditions so considered being relative to the meteorological state of the atmosphere, to the configuration of terrain, to the functioning of the aircraft, to the efficiency of personnel and to all the factors affecting safety in flight. Anticipated operating conditions do not include:

a)  those extremes which can be effectively avoided by means of operating procedures; and 

b)  those extremes which occur so infrequently that to require the Standards to be met in 

     such extremes would give a higher level of airworthiness than experience has shown to be 

     necessary and practical. 

Appliance means any instrument, mechanism, equipment, part, apparatus, appurtenance, or accessory, including communications equipment, that is used or intended to be used in operating or controlling an aircraft in flight, is installed in or attached to the aircraft, and is not part of an airframe, engine, or propeller. 

Approach control service. Air traffic control service for arriving or departing controlled flights. 

Approach control unit. A unit established to provide air traffic control service to controlled flights arriving at, or departing from, one or more aerodromes. 

Approach and landing operations using instrument approach procedures. Instrument approach and landing operations are classified as follows: 

   Non-precision approach and landing operations. An instrument approach and landing  

   which utilizes lateral guidance but does not utilize vertical guidance.

   Approach and landing operations with vertical guidance. An instrument approach and 

   landing which utilizes lateral and vertical guidance but does not meet the requirements established 

   for precision approach and landing operations. 

   Precision approach and landing operations. An instrument approach and landing using 

   precision lateral and vertical guidance with minima as determined by the category of operation. 

Approach and landing phase helicopters. That part of the flight from 300 m (1 000 ft) above the elevation of the FATO, if the flight is planned to exceed this height, or from the commencement of the descent in the other cases, to landing or to the balked landing point. 

Appropriate airworthiness requirements. The comprehensive and detailed airworthiness codes established, adopted or accepted by a State for the class of aircraft, engine or propeller under consideration.

Appropriate authority.
a) Regarding flight over the high seas: The relevant authority of the State of Registry. 

b) Regarding flight other than over the high seas: The relevant authority of the State having 

    sovereignty over the territory being overflown. 

Appropriate ATS authority. The relevant authority designated by the State responsible for providing air traffic services in the airspace concerned. 

Approved. Accepted by a Directorate General of Civil Aviation as suitable for a particular purpose. 

Approved maintenance organization. An organization approved by a DGCA, in accordance with the requirements of CASR Part 145 - Aircraft Maintenance, to perform maintenance, preventive maintenance, or alterations of an aircraft, airframe, aircraft engine, propeller, appliances, or components of aircraft or parts thereof and operating under supervision approved by DGCA. 

Approved training. Training carried out under special curricula and supervision approved by a Contracting State. 

Apron. A defined area, on a land aerodrome, intended to accommodate aircraft for purposes of loading or unloading passengers, mail or cargo, fuelling, parking or maintenance. 

Area control centre. A unit established to provide air traffic control service to controlled flights in control areas under its jurisdiction. 

Area control service. Air traffic control service for controlled flights in control areas. 

Area minimum altitude (AMA). The lowest altitude to be usedunder instrument meteorological conditions (IMC) that will provide a minimum vertical clearance of 300 m (1 000 ft) or in designated mountainous terrain 600 m (2 000 ft) above all obstacles located in the area specified, rounded up to the nearest (next higher) 30 m (100 ft).

Area navigation (RNAV) means a method of navigation that permits aircraft operations on any desired course within the coverage of station referenced navigation signals or within the limits of self-contained system capability. 

Area navigation high route means an area navigation route within the airspace extending upward from, and including, 18,000 feet MSL to flight level 450. 

Area navigation low route means an area navigation route within the airspace extending upward from 1,200 feet above the surface of the earth to, but not including, 18,000 feet MSL. 

Area navigation (RNAV) is a method of navigation that permits aircraft operations on any desired flight path. 

Area navigation (RNAV) route is an ATS route based on RNAV that can be used by suitably equipped aircraft. 

Armed Forces means the Army, Navy, Air Force, and , including their regular and reserve components and members serving without component status. 

Arrival routes. Routes identified in an instrument approach procedure by which aircraft may proceed from the en-route phase of flight to an initial approach fix. 

ASHTAM. A special series NOTAM notifying by means of a specific format change in activity of a volcano, a volcanic eruption and/or volcanic ash cloud that is of significance to aircraft operations. 

ATS route. A specified route designed for channelling the flow of traffic as necessary for the provision of air traffic services. 

Automatic dependent surveillance (ADS). A surveillance technique in which aircraft automatically provide, via a data link, data derived from on-board navigation and position-fixing systems, including aircraft identification, four-dimensional position and additional data as appropriate. 

    ADS agreement. An ADS reporting plan which establishes the conditions of ADS data reporting (i.e. data required by the air traffic services unit and frequency of ADS reports which have to be agreed to prior to the provision of the ADS services). 

    ADS application. An ATN application that provides ADS data from the aircraft to the ATS unit(s) for surveillance purposes. 

    ADS contract. A means by which the terms of an ADS agreement will be exchanged between the ground system and the aircraft, specifying under what conditions ADS reports would be initiated, and what data would be contained in the reports. 

Autorotation means a rotorcraft flight condition in which the lifting rotor is driven entirely by action of the air when the rotorcraft is in motion. 

Automatic relay installation. A teletypewriter installation where automatic equipment is used to transfer messages from incoming to outgoing circuits.

Automatic telecommunication log. A record of the activities of an aeronautical telecommunication station recorded by electrical or mechanical means. 

Auxiliary rotor means a rotor that serves either to counteract the effect of the main rotor torque on a rotorcraft or to maneuver the rotorcraft about one or more of its three principal axes. 

Aviation means anything relating to the use of airspace , aircraft, airports, concerning air transport, aviation security and safety, and other related activities and supporting facilities.