Article 2
The terms used in these rules are defined as follows:
1. Acrobatic Flight
Manoeuvers intentionally performed by an aircraft involving an abrupt change in its attitude, an abnormal attitude, or an abnormal variation in speed.
2. Automatic dependent surveillance — broadcast (ADS-B).
A means by which aircraft, aerodrome vehicles and other objects can automatically transmit and/or receive data such as identification, position and additional data, as appropriate, in a broadcast mode via a data link.
3. ADS-C agreement.
A reporting plan which establishes the conditions of ADS-C data reporting (i.e. data required by the air traffic services unit and frequency of ADS-C reports which have to be agreed to prior to using ADS-C in the provision of air traffic services).
4. Automatic dependent surveillance — contract (ADS-C).
A means by which the terms of an ADS-C agreement will be exchanged between the ground system and the aircraft, via a data link, specifying under what conditions ADS-C reports would be initiated, and what data would be contained in the reports.
5. Aerodrome
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.
6. Aerodrome control service
Air traffic control service for aerodrome traffic.
7. Aerodrome control tower
A unit established to provide air traffic control service to aerodrome traffic.
8. Aerodrome traffic
All traffic on the manoeuvring area of an aerodrome and all aircraft flying in the vicinity of an aerodrome.
9. Aerodrome traffic zone
An airspace of defined dimensions established around an aerodrome for the protection of aerodrome traffic.
10. 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.
11. 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.
12. 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.
13. 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.
14. 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.
15. Air traffic control clearance
Authorization for an aircraft to proceed under conditions specified by an air traffic control unit.
16. Air traffic control (ATC) service
A service provided for the purpose of preventing collisions between aircraft, and on the manoeuvring area between aircraft and obstructions, and expediting and maintaining an orderly flow of air traffic.
17. Air traffic control unit
A generic term meaning variously, area control center, approach control office or aerodrome control tower.
18. Air traffic service (ATS)
A generic term meaning variously, flight information service, alerting service, air traffic control service（area control service, approach control service or aerodrome control service）.
19. Air traffic services unit
A generic term meaning variously, flight information center or air traffic control unit.
20. Airway
Means a control area or portion thereof established by the CAA in the form of a corridor.
21. Alerting service
A service provided to notify appropriate organizations regarding aircraft in need of search and rescue aid, and assist such organizations as required.
22. 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.
23. Altitude
The vertical distance of a level, a point or an object considered as a point, measured from mean sea level (MSL).
24. Approach control service
Air traffic control service for arriving or departing controlled flights.
25. Appropriate ATS authority
The relevant authority designated by the State responsible for providing air traffic services in the airspace concerned.
26. Area control center
A unit established to provide air traffic control service to controlled flights in control areas under its jurisdiction.
27. ATS route
A specified route designed for channeling the flow of traffic as necessary for the provision of air traffic services.
28. Ceiling
The height above the ground or water of the base of the lowest layer of cloud below 20,000 ft covering more than half the sky.
29. Changeover point
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.
30. Control area
A controlled airspace extending upwards from a specified limit above the earth.
31. Controlled aerodrome
An aerodrome at which air traffic control service is provided to aerodrome traffic.
32. Controlled airspace
An airspace of defined dimensions within which air traffic control service is provided in accordance with the airspace classification, including of Classes A, B, C, D, E and class E surface airspace.
33. Controlled flight
Any flight which is subject to an air traffic control clearance.
34. Control zone
A controlled airspace extending upwards from the surface of the earth to a specified upper limit.
35. Cruising level
A level maintained during a significant portion of a flight.
36. Current flight plan
The flight plan, including changes, if any, brought about by subsequent clearances.
37. Danger area
An airspace of defined dimensions within which activities dangerous to the flight of aircraft may exist at specified times.
38. Data link communications
A form of communication intended for the exchange of messages via a data link.
39. Estimated off-block time
The estimated time at which the aircraft will commence movement associated with departure.
40. Expected approach time
The time at which ATC expects that an arriving aircraft, following a delay, will leave the holding point to complete its approach for a landing.
41. Filed flight plan
The flight plan as filed with an ATS unit by the pilot or a designated representative, without any subsequent changes.
42. Flight crew member
A licensed crew member charged with duties essential to the operation of an aircraft during flight time.
43. Flight information center
A unit established to provide flight information service.
44. Flight information region (FIR)
An airspace of defined dimensions within which flight information service and alerting service are provided.
45. Flight information service
A service provided for the purpose of giving advice and information useful for the safe and efficient conduct of flights.
46. Flight level (FL)
A surface of constant atmospheric pressure which is related to a specific pressure datum, 1 013.2 hectopascals (hPa) (29.92 inches), and is separated from other such surfaces by specific pressure intervals.
47. Flight plan
Specified information provided to air traffic services units, relative to an intended flight or portion of a flight of an aircraft.
48. Flight visibility
The visibility forward from the cockpit of an aircraft in flight.
49. Ground visibility
The visibility at an aerodrome, as reported by an accredited observer.
50. Heading
The direction in which the longitudinal axis of an aircraft is pointed, usually expressed in degrees from true north, magnetic north, compass north or grid north.
51. Height
The vertical distance of a level, a point or an object considered as a point, measured from a specified datum.
52. Instrument flight rules (IFR) flight
A flight conducted in accordance with the instrument flight rules.
53. Instrument approach procedure
A series of predetermined manoeuvres by reference to flight instruments with specified protection from obstacles from the initial approach fix, or where applicable, from the beginning of a defined arrival route to a point from which a landing can be completed and thereafter, if a landing is not completed, to a position at which holding or en-route obstacle clearance criteria apply. Instrument approach procedures are classified as follows:
(1) Non-precision approach procedure. An instrument approach procedure which utilizes lateral guidance but does not utilize vertical guidance.
(2) Approach procedure with vertical guidance. An instrument approach procedure which utilizes lateral and vertical guidance but does not meet the requirements established for precision approach and landing operations.
(3) Precision approach procedure. An instrument approach procedure using precision lateral and vertical guidance with minima as determined by the category of operation.
54. Instrument meteorological condition (IMC)
Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling, less than the minima specified for visual meteorological conditions.
55. Level
A generic term relating to the vertical position of an aircraft in flight and meaning variously, height, altitude or flight level
56. Manoeuvring area
That part of an aerodrome to be used for the take-off, landing and taxiing of aircraft, excluding aprons.
57. 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).
58. Pilot-in-command
The pilot designated by the operator, or in the case of general aviation, the owner, as being in command and charged with the safe conduct of a flight.
59. Problematic use of substances
The use of one or more psychoactive substances by aviation personnel in a way that: (1) constitutes a direct hazard to the user or endangers the lives, health or welfare of others. (2) causes or worsens an occupational, social, mental or physical problem or disorder.
60. 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.
61. Psychoactive substances
Alcohol, opioids, cannabinoids, sedatives and hypnotics, cocaine, other psychostimulants, hallucinogens, and volatile solvents, whereas coffee and tobacco are excluded.
62. Reporting point
A specified geographical location in relation to which the position of an aircraft can be reported.
63. 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.
64. Runway
A defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft.
65. Runway-holding position
A designated position intended to protect a runway, an obstacle limitation surface, or an ILS/MLS critical/sensitive area at which taxiing aircraft and vehicles shall stop and hold, unless otherwise authorized by the aerodrome control tower.
66. Safety-sensitive personnel
Persons who might endanger aviation safety if they perform their duties and functions improperly including, but not limited to, crew members, aircraft maintenance personnel and air traffic controllers.
67. Special VFR flight
A VFR flight requested by pilot and cleared by air traffic control to operate within a control zone in meteorological conditions below VMC.
68. Taxiing
Movement of an aircraft on the surface of an aerodrome under its own power, excluding take-off and landing.
69. Total estimated elapsed time
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, the estimated time required from take-off to arrive over the destination aerodrome.
70. 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 true north, magnetic north or grid north.
71. Traffic information
Information issued by an air traffic services unit to alert a pilot to other known or observed air traffic which may be in proximity to the position or intended route of flight and to help the pilot avoid a collision.
72. Transition altitude
The altitude at or below which the vertical position of an aircraft is controlled by reference to altitudes.
73. Unmanned free balloon. A non-power-driven, unmanned, lighter-than-air aircraft in free flight.
74. Visual flight rules (VFR) flight
A flight conducted in accordance with the visual flight rules.
75. Visibility
Visibility for aeronautical purposes is the greater of：
(1) the greatest distance at which a black object of suitable dimensions, situated near the ground, can be seen and recognized when observed against a bright background;
(2) the greatest distance at which lights in the vicinity of 1000 candelas can be seen and identified against an unlit background.
76. Visual meteorological condition (VMC)
Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling equal to or better than specified minima.
77. Tables of cruising level
Tables of cruising level designated in accordance with the magnetic track 000°-179° and 180°-359°.
78. Transition level
The lowest flight level available for use above the transition altitude.
79. Air defense identification zone (ADIZ)
An airspace specified for the purpose of national defense within which the control and swift identification and location of an aircraft is required.
80. Night
The hours between the end of evening civil twilight and the beginning of morning civil twilight.
81. Small aircraft
Aircraft with maximum take-off weight less than or equal to 5,700 kg, exclude ultra light vehicles.
82. VFR flight following
A service provided by ATS unit to pilot of small VFR aircraft by maintaining air-ground communications, and monitoring the aircraft movement.
83. Area navigation
A method of navigation which permits aircraft operation on any desired flight path within the coverage of station-referenced navigation aids or within the limits of the capability of self-contained aids, or a combination of these.
84. Regional air navigation agreement
An agreement approved by the Council of ICAO normally on the advice of a Regional Air Navigation Meeting.
85. Free balloon
Non-power-driven, one lighter-than-air aircraft, includes inflatable free balloon and hot-air free balloon.