Definitions

Definitions

A

Aerodrome
A defined area of land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure and movement of aircraft.
Aerodrome beacon
An aeronautical beacon used to indicate the location of an aerodrome from the air.
Aerodrome control service
ATC service for aerodrome traffic.
Aerodrome control tower
A unit established to provide ATC service to aerodrome traffic.
Aerodrome elevation
The elevation of the highest point of the landing area.
Aerodrome meteorological minima (ceiling and visibility minima)
The minimum heights of cloud base (ceiling) and minimum values of visibility which are prescribed in pursuance of CAR 257 for the purpose of determining the useability of an aerodrome either for take-off or landing.
Aerodrome proprietor
Any owner, licensee, authority, corporation, or any other body which has a legal responsibility for a particular aerodrome.
Aerodrome reference point (ARP)
The designated geographical location of an aerodrome.
Aerodrome traffic
All traffic on the manoeuvring area of an aerodrome and all aircraft flying in, entering, or leaving the traffic circuit.
Aerodrome traffic circuit
The specified path to be flown by aircraft flying in, entering, or leaving the traffic circuit.
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 Information Circular (AIC)
A notice containing information that does not qualify for the origination of a NOTAM, or for inclusion in the AlP, 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 supplement (SUP)
Temporary changes to the information contained in the AIP which are published by means of special pages.
Aircraft classification number (ACN)
A number expressing the relative effect of an aircraft on a pavement for a specific standard sub-grade category.
Aircraft parking position taxi lane
A portion of an apron designated as a taxiway and intended to provide access to aircraft parking positions only.
Air-ground communications
Two-way communications between aircraft and stations on the surface of the Earth.
Airprox
The combination of the two words, air and proximity. An occurrence in which aircraft come into such close proximity that a threat to the safety of the aircraft exists or may exist, in airspace where the aircraft are not subject to an air traffic separation standard, or where separation is a pilot responsibility.
Air report (AIREP)
A report from an aircraft in flight prepared by the pilot during the course of a flight in conformity with the requirements for position, operational or meteorological reporting in the AIREP form.
Air taxiing
Movement of a helicopter/VTOl above the surface of an aerodrome, normally in ground effect and at a speed normally less that 20 kt.
Air traffic control clearance
Authorisation for aircraft to proceed under conditions specified by an air traffic control unit.
Air traffic control instructions
Directives issued by air traffic control for the purpose of requiring a pilot to take a specific action.
Air traffic control 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.
Air traffic service (ATS)
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).
Air transit
The airborne movement of a helicopter that is:
  • for the expeditious transit from one place within an aerodrome to another place within the aerodrome
  • at or below 100 ft above the surface and
  • at speeds greater than those used in air taxiing.
Airways clearance
A clearance, issued by ATC, to operate in controlled airspace along a designated track or route at a specified level to a specified point or flight planned destination.
Alerted see-and-avoid
A procedure where flight crew, having been alerted to the existence and approximate location of other traffic in their immediate vicinity, seek to sight and avoid colliding with those aircraft.
Alerting post
An agency designated to serve as an intermediary between a person reporting an aircraft in distress and a rescue coordination centre.
Alerting service
A service provided to notify appropriate organisations regarding aircraft in need of search and rescue aid, and to assist such organisations 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.
Altimeter setting
A pressure datum which when set on the sub-scale of a sensitive altimeter causes the altimeter to indicate vertical displacement from that datum. A pressure-type altimeter calibrated in accordance with standard atmosphere may be used to indicate altitude, height or flight levels, as follows:
  • when set to QNH or Area QNH it will indicate altitude
  • when set to standard pressure (1013.2 HPa) it may be used to indicate flight levels.
Altimeter setting region
Airspace 10,000 ft and below where the sub-scale of a pressure sensitive altimeter is set to QnH or Area QnH.
Altitude
The vertical distance of a level, a point or an object, considered as a point, measured from mean sea level.
Approach control service
ATC service for arriving or departing flights.
Approach sequence
The order in which two or more aircraft are cleared to approach to land at the aerodrome.
Apron
A defined area on a land aerodrome, intended to accommodate aircraft for purposes of loading or unloading passengers, mail, cargo, fuelling, parking or maintenance.
Apron service
A traffic regulatory and information service provided to aircraft using the apron area of an aerodrome.
Apron taxiway
A portion of a taxiway system located on an apron and intended to provide a through taxi route across the apron.
Area control service
Air traffic control service for controlled flights in control areas.
Area navigation (RNAV)
A method of navigation which permits aircraft operation on any desired flight path within the coverage of ground or space-based navigation aids, or within the limits of the capability of self-contained aids, or a combination of these.
Area navigation (RNAV) route
An ATS route established for the use of aircraft capable of employing area navigation.
Area QNH
A forecast altimeter setting which is representative of the QNH of any location within a particular area.
ATS route
A specified route designed for channelling the flow of traffic as necessary for the provision of air traffic services.
ATS surveillance service
Term used to indicate an air traffic service provided directly by means of an ATS surveillance system.
ATS surveillance system
A generic term meaning variously, ADS-B, PSR, SSR or any comparable ground-based system that enables the identification of aircraft.
Automatic dependent surveillance – broadcast (ADS-B)
A means by which aircraft, aerodrome vehicles and other objects can automatically transmit or receive data such as identification, position and additional data, as appropriate, in a broadcast mode via a data link.
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.
Automatic En Route Information Service (AERIS)
The provision of operational information en route by means of continuous and repetitive broadcasts.
Automatic Terminal Information Service (ATIS)
The provision of current, routine information to arriving and departing aircraft by means of continuous and repetitive broadcasts during the hours when the unit responsible for the service is in operation.
Aviation reference number (ARN)
A unique six-digit number used to identify a client who conducts business with CASA. When CASA receives an application for a new licence, certificate, or other service, an ARN is established and all subsequent transactions for the client are recorded against that ARN. In addition to being a client number, the ARN can also be the licence or certificate number. The ARN should be quoted in all correspondence with CASA or with the Airservices Publications unit.

B

Base turn (instrument approach)
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.
Blind transmission
A transmission from one station to another station in circumstances where two-way communication cannot be established, but where it is believed that the called station is able to receive the transmission.
Block level
A section of airspace with specified upper and lower limits on a specific track, in which cleared aircraft are permitted to manoeuvre.
Break-out procedure
A procedure initiated on instruction from a precision runway monitor (PRM) controller upon which a pilot is required to discontinue an ILS approach and immediately commence a turn of approximately 90 degrees from the ILS course, climbing (or descending) as instructed by ATC, in response to an aircraft deviating from the adjacent ILS course.
Briefing
The act of giving in advance, specific pre-flight instructions or information to aircrew.
Broadcast
A transmission of information relating to air navigation for which an acknowledgement is not expected.

C

Ceiling
The height above the ground or water of the base of the lowest layer of cloud below 20,000 ft covering more than one-half of the sky.
CENSAR
An automated centralised SARTIME database software package used by ATS to manage SARTIMEs.
Centre
A generic call sign used in the en route and area environment which can include air traffic control, advisory, flight information and alerting services, depending on the classification of airspace in which the service is provided.
Circling approach
An extension of an instrument approach procedure which provides for visual circling of the aerodrome prior to landing.
Clearance expiry time
A time specified by an air traffic control unit at which a clearance ceases to be valid.
Clearance limit
The point to which an aircraft is granted an air traffic control clearance.
Clearway
A defined rectangular area on the ground or water under the control of the appropriate authority, selected or prepared as a suitable area over which an aeroplane may make a portion of its initial climb to a specified height.
Co-located navigation aids
En route way-points or navigation aids that are within 600 m of each other.
Common traffic advisory frequency (CTAF)
A designated frequency on which pilots make positional broadcasts when operating in the vicinity of a non-controlled aerodrome.
Communicable diseases
Communicable diseases include cholera, typhus (epidemic), smallpox, yellow fever, plague, and such other diseases as the contracting states shall, from time to time, decide to designate.
Company operations representative
The representative of an operating agency who is authorised to act in the capacity of liaison officer between ATC and the operating agency in respect of the control of an aircraft of that agency.
Control area (CTA)
A controlled airspace extending upwards from a specified limit above the Earth.
Controlled aerodrome
An aerodrome at which air traffic control service is provided to aerodrome traffic.
Controlled airspace
Airspace of defined dimensions within which air traffic control service is provided in accordance with the airspace classification.
Controller
An air traffic controller, operating within an organisation approved under CASR Part 172 and qualified in accordance with CASR Part 65.
Controller pilot data link communications (CPDLC)
A means of communication between controller and pilot using data link for ATC communications.
Control zone (CTR)
A controlled airspace extending upwards from the surface of the Earth to a specified upper limit.
Cruise climb
An aeroplane cruising technique resulting in a nett increase in altitude as the aeroplane weight decreases.
Cruising level
A level maintained during a significant portion of a flight.

D

Danger area
An airspace of defined dimensions within which activities dangerous  to the flight of aircraft may exist at specified times.
Day
That period of time from the beginning of morning civil twilight to the end of evening civil twilight.
Dead reckoning (DR) navigation
The estimating or determining of position by advancing an earlier known position by the application of direction, time and speed data.
Decision altitude/height (DA/H)
A specified altitude or height in the precision approach at which a missed approach must be initiated if the required visual reference to continue the approach has not been established.
Density height
An atmospheric density expressed in terms of height which corresponds to that density in the Standard Atmosphere.
Dependent parallel approaches
Simultaneous approaches to parallel instrument runways where radar separation minima between aircraft on adjacent extended runway centre-lines are prescribed.
Distance measuring equipment (DME)
Equipment which measures in nautical miles, the slant range of an aircraft from the selected DME ground station.
DME distance
The slant range from the source of a dME signal to the receiving antenna.
Domestic flight
A flight between two points within the Australian FIR.

E

Elevation
The vertical distance of a point or a level, on or affixed to the surface of the Earth, measured from mean sea level.
Emergency phases:
Uncertainty phase
A situation where uncertainty exists as to the safety of an aircraft and its occupants.
Alert phase
A situation where apprehension exists as to the safety of an aircraft and its occupants.
Distress phase
A situation wherein there is reasonable certainty that an aircraft and its occupants are threatened by grave and imminent danger or require immediate assistance.
Equivalent single isolated wheel load
The equivalent load that would be imposed on a pavement by a single wheel if any wheel group on an aircraft were replaced by a single wheel using the same tyre pressure.
Essential radio navigation service
A radio navigation service whose disruption has a significant impact  on operations in the affected airspace or aerodrome.
Estimate
The time at which it is estimated that an aircraft will be over a position reporting point or over the destination.
Estimated elapsed time (EET)
The estimated time required to proceed from one significant point to another.
Estimated off block time (EOBT)
The estimated time at which the aircraft will commence movement associated with departure.
Estimated time of arrival (ETA)
For IFR flights, the time at which it is estimated that the aircraft will 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 aerodrome, the time at which the aircraft will arrive over the aerodrome. For VFR flights, the time at which it is estimated that the aircraft will arrive over the aerodrome.
Expected approach time (EAT)
The time at which ATC expects that an arriving aircraft, following a delay, will leave the holding fix to complete its approach for a landing.

F

Final approach
That part of an instrument approach procedure which commences at the specified final approach fix or point, or where such a fix or point is not specified:
  • at the end of the last procedure turn, base turn or inbound turn of a racetrack procedure, if specified; or
  • at the point of interception of the last track specified in the approach procedure; and
  • ends at a point in the vicinity of an aerodrome from which a landing can be made, or a missed approach initiated.
Final approach altitude
The specified altitude at which final approach  is commenced.
Final approach fix (FAF)
A specified point on a non-precision instrument approach which identifies the commencement of the final segment.
Final approach point (FAP)
A specified point on the glide path of a precision instrument approach which identifies the commencement of the final segment.
Final approach segment
That segment of an instrument approach procedure  in which alignment and descent for landing are accomplished.
Final leg
The path of an aircraft in a straight line immediately preceding the landing (alighting) of the aircraft.
Fix
A geographical position of an aircraft at a specific time determined  by visual reference to the surface, or by navigational aids.
Flight file
A file stored on the NAIPS system which contains stored briefings, or a stored flight notification. Flight files are owned by pilots and/or operators, and updated at their request.
Flight following
The provision of an ongoing Radar/ADS-B Information Service (RIS).
Flight Identification (FLT ID)
An identification of up to 7 alpha-numeric characters entered by the pilot via a cockpit interface. Where possible, the Flight Identification must match the Aircraft Identification entered into Item 7 of the Flight Notification.
Flight information
Information useful for the safe and efficient conduct of flight, including information on air traffic, meteorological conditions, aerodrome conditions and airways facilities.
Flight Information Area (FIA)
An airspace of defined dimensions, excluding controlled airspace, within which flight information and SAR alerting services are provided by an ATS unit.
Flight Information Centre (FIC)
A unit established to provide flight information service and SAR alerting service.
Flight Information Region (FIR)
An airspace of defined dimensions within which flight information service and SAR alerting service are provided.
Flight Information Service (FIS)
A service provided for the purpose of giving advice and information useful for the safe and efficient conduct of flights.
Flight Level (FL)
A surface of constant atmospheric pressure which is related  to a specific pressure datum, 1013.2 HPa, and is separated from other such surfaces by specific pressure intervals.
Flight Note
Details of the route and timing of a proposed flight provided by the pilot-in-command of an aircraft, which is other than notification submitted to Airservices Australia, and which is required to be left with a person who could be expected to notify appropriate authorities in the event that the flight becomes overdue.
Flight notification  (within Australian FIR)
Specified information provided to air traffic services units, relative to the intended flight or portion of flight of an aircraft.
Flight path monitoring
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 air traffic control clearances.
Flight visibility
The visibility forward from the cockpit of an aircraft in flight.
Forecast
A statement of expected meteorological conditions for a specified period, and for a specified area or portion of airspace.
Formation
Two or more aircraft flown in close proximity to each other and operating as a single aircraft with regard to navigation, position reporting and control.
Full emergency (in the context of aerodrome emergency plans)
A situation in which the response of all agencies involved in the aerodrome emergency plan will be activated. A full emergency will be declared when an aircraft approaching the airport is known or suspected to be in such trouble that there is danger of an accident.

G

Glide path (GP)
A descent profile determined for vertical guidance during a final approach.
Global navigation satellite system (GNSS)
A satellite-based radio navigation system that uses signals from orbiting satellites to determine precise position and time.
Global positioning system (GPS)
A GNSS constellation operated by the United States Government.
Gross weight
The weight of the aircraft together with the weight of all persons and goods (including fuel) on board the aircraft at that time.
Ground-based navigation aid
Refers to NDB, VOR, DME.
Ground taxiing
The movement of a helicopter under its own power and on its undercarriage wheels.
Ground visibility
The visibility at an aerodrome, as reported by an accredited observer.

H

Hazardous conditions
Meteorological conditions which may endanger aircraft or adversely affect their safe operation, particularly those phenomena associated with volcanic ash cloud and thunderstorms – icing, hail and turbulence.
Heading (HDG)
The direction in which the longitudinal axis of an aircraft is pointed, usually expressed in degrees from north (true, magnetic, compass or grid).
Heading (HDG)
The direction in which the longitudinal axis of an aircraft is pointed, usually expressed in degrees from north (true, magnetic, compass or grid).
Height
The vertical distance of a level, a point or an object considered as a point measured from a specified datum.
Height above aerodrome (HAA) (non-precision approach or circling)
The height of the minimum descent altitude above the published aerodrome elevation.
Height above threshold (HAT) (precision approach)
The height of the decision altitude above the threshold elevation.
Helicopter access corridor
A corridor wholly within controlled airspace designed for the exclusive use of helicopters in VMC. The extent and alignment of the corridor is related to and delineated by prominent geographical/topographical features.
Helicopter landing site (HLS)
A place that is used as an aerodrome for the purposes of the landing and taking off of helicopters.
Helicopter lane
A lane, outside controlled airspace, designed for use by helicopters  to facilitate traffic flow.
Helicopter movement area
The movement area for helicopters is that part of an aerodrome that can safely be used for the hovering, taxiing, take-off and landing of helicopters and consists of the manoeuvring area and aprons, but excluding those areas reserved for unrestricted use by the general public.
High capacity aircraft
An aircraft that is certified as having a maximum seating capacity exceeding 38 seats, or a maximum payload exceeding 4200 kg.
Holding bay
A defined area where aircraft can be held, or bypassed, to facilitate efficient surface movement of aircraft.
Holding fix
A specified location identified by visual or other means in the vicinity  of which the position of an aircraft in flight is maintained in accordance with ATC instructions.
Holding procedure
A predetermined manoeuvre which keeps an aircraft within a specified airspace whilst awaiting further clearance.
Hold short line/lights
A line marked across a runway, with associated lights, in accordance with the requirements of AIP AD 1.1, at which landing aircraft must stop when required during land and hold short operations (LAHSO).
Hospital aircraft
A priority category for use by international aircraft when medical priority is required (see also Medical).
Hot spot
A location on an aerodrome movement area with a history or potential risk of collision or runway incursion, and where heightened attention by pilots/ drivers is necessary.

I

ICAO 24-bit aircraft address (24-bit code)
A unique identification code which is programmed into each specific aircraft’s transponder or ADS-B transmitter during installation. This code, expressed as six alphanumeric characters, provides a digital identification of the aircraft and is used by the air traffic system to link information contained in a flight notification to aircraft position information received via ADS-B.
Identification
The situation which exists when the position indication of a particular aircraft is seen on a situation display and positively identified by ATC.
IFR pick-up
A pilot procedure whereby a flight operating to the IFR in Class G airspace changes to VFR upon entering Class E airspace whilst awaiting an airways clearance. IFR pick-up is limited to FL180 and below.
Independent parallel approaches
Simultaneous approaches to parallel or near-parallel instrument runways where radar separation minima between aircraft on adjacent extended runway centre lines are not prescribed. The two types of independent approaches are:
  • Independent visual approaches – during which a pilot is responsible for separation from the aircraft on the other approach and
  • ILS PRM approaches – during which separation between aircraft on adjacent ILS courses is maintained using PRM.
Independent parallel departures
Simultaneous departures in the same direction from parallel or near-parallel instrument runways.
Inertial navigation/ reference system (INS/IRS)
A self-contained navigation system that continually measures the acceleration acting upon the vehicle of which it is part. Suitably integrated, these forces provide velocity and thence position information.
Initial approach fix (IAF)
The fix at the commencement of an instrument approach.
Initial approach segment
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.
Instrument approach and landing operations:
Non-precision approach and landing operations
Instrument approaches and landings which do not utilise electronic glide path guidance.
Precision approach and landing operations
Instrument approaches and landings using precision azimuth and glide path guidance with minima as determined by the category of operation. Categories of precision approach and landing operations are:
  • Category I (CAT I) operation – a precision instrument approach and landing with a decision height not lower than 200 ft and a visibility not less than 800 m, or a runway visual range (RVR) not less than 550 m.
  • Category II (CAT II) operation – a precision instrument approach and landing with a decision height lower than 200 ft but not lower than 100 ft, and an RVR not less than 350 m.
  • Category IIIA (CAT IIIA) operation – a precision instrument approach and landing with a decision height lower than 100 ft, or no decision height and an RVR not less than 200 m.
  • Category IIIB (CAT IIIB) operation – a precision instrument approach and landing with either, a decision height lower than 50 ft, or with no decision height and an RVR less than 200 m but not less than 50 m.
  • Category IIIC (CAT IIIC) operation – a precision instrument approach and landing with no decision height and no RVR limitations.
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 landing system (ILS)
A precision instrument approach system which normally consists of the following electronic components VHF localiser, UHF glideslope, VHF marker beacons.
Instrument runway
One of the following types of runways intended for the operation of aircraft using instrument approach procedures:
Non-precision approach runway
An instrument runway served by visual aids and a non-visual aid providing at least directional guidance adequate for a straight-in approach.
Precision approach runway, CAT I
An instrument runway served by ILS and visual aids intended for operations with a decision height not lower than 200 ft and either a visibility not less than 800 m, or an RVR not less than 550 m.
Precision approach runway, CAT Il
An instrument runway served by ILS and visual aids intended for operations with a decision height lower than 200 ft, but not lower than 100 ft and an RVR not less than 350 m.
Precision approach runway, CAT Ill
An instrument runway served by IlS to and along the surface of the runway and:
  • for CAT IIIA – intended for operations with a decision height lower than 100 ft, or no decision height and an RVR not less than 200 m
  • for CAT IIIB – intended for operations with a decision height lower than 50 ft, or no decision height and an RVR less than 200 m, but not less than 50 m
  • for CAT IIIC – intended for operations with no decision height and no RVR limitations.
Integrated aeronautical information package
A package which comprises the following: AIP, including amendment service; supplements to the AIP Preflight Information Bulletins (PIBs); and checklists and summaries.
Integrity
That quality which relates to the trust which can be placed in the correctness of information supplied by a system. It includes the ability  of a system to provide timely warnings to users when the system should not be used for navigation.
Intermediate approach segment
That segment of an instrument approach procedure between either the intermediate approach fix and the final approach fix or point, or between the end of the reversal, race track or dead reckoning track procedure and the final approach fix or point, as appropriate.
Intermediate fix (IF)
A fix on an RNAV approach that marks the end of an initial segment and the beginning of the intermediate segment.
In the vicinity
An aircraft is in the vicinity of a non-towered aerodrome if it is within  a horizontal distance of 10 miles; and within a height above the aerodrome reference point that could result in conflict with operations at the aerodrome.

L

Land and hold short operations (LAHSO)
A procedure involving dependent operations conducted on two intersecting runways whereby aircraft land and depart on one runway while aircraft landing on the other runway hold short of the intersection.
Landing area
That part of the movement area intended for the landing or take-off  of aircraft.
Land rescue unit
A land party equipped to undertake a search for an aircraft within the region of its responsibility.
Level
A generic term relating to the vertical position of an aircraft in flight and meaning variously, height, altitude or flight level.
Licensed aerodrome
A place that is licensed as an aerodrome under the Civil Aviation Regulations.
Localiser (LOC)
The component of an ILS which provides azimuth guidance to a runway. It may be used as part of an ILS or independently.
Local standby (in the context of aerodrome emergency plans)
A situation in which activation of only the airport-based agencies involved in the aerodrome emergency plan is warranted. A local standby will be the normal response when an aircraft approaching an airport is known or is suspected to have developed some defect, but the trouble is not such as would normally involve any serious difficulty in effecting a safe landing.
Long range navigation system (LRNS)
Area navigation systems limited to INS/IRS or GPS.
Lowest safe altitude (LSALT)
The lowest altitude which will provide safe terrain clearance at a given place.
Low jet route (LJR)
A route, or part of a route, at or below 5000 ft AGL used by MLJ aircraft for low level, high speed navigation and/or terrain following exercises.

M

Manoeuvring area
That part of an aerodrome to be used for the take-off, landing and taxiing of aircraft, excluding aprons.
Marker
An object displayed above ground level in order to indicate an obstacle  or delineate a boundary.
Marker beacon
A type of radio beacon, the emissions of which radiate in a vertical pattern.
Markings
A symbol or group of symbols displayed on the surface of the movement area in order to convey aeronautical information.
Maximum take-off weight (MTOW)
The maximum take-off weight of an aircraft as specified in its certificate of airworthiness.
Medical flight
A flight providing transport of medical patients, personnel, and/or equipment, prioritised as follows:
  • MED 1—An aircraft proceeding to pick up, or carrying, a severely ill patient, or one for whom life support measures are being provided
  • MED 2—An aircraft proceeding to pick up medical personnel and/or equipment urgently required for the transport of a MED 1 patient, or returning urgently required medical personnel and/or equipment at the termination of a MED 1 flight.
Automated meteorological telephone briefing (METBRIEF)
Self help system which delivers meteorological information on the telephone using a computer-generated voice, in response to a tone-generated telephone request.
Meteorological information
Meteorological report, analysis, forecast, and any other statement relating to existing or expected meteorological conditions.
Meteorological office (MO)
An office designated to provide meteorological services for air navigation.
Meteorological warning
A statement or meteorological report of the occurrence or expectation  of a deterioration or improvement in meteorological conditions or of any meteorological phenomenon which may seriously affect the safe operation of aircraft.
Minimum altitude
The minimum altitude for a particular instrument approach procedure is the altitude specified by AIP DAP at which an aircraft shall discontinue an instrument approach unless continual visual reference to the ground or water has been established and ground visibility is equal to or greater than that specified by the DAP for landing.
Minimum descent altitude (MDA)
A specified altitude in a non-precision runway or circling approach below which descent may not be made without visual reference.
Minimum fuel
The term used to describe a situation in which an aircraft’s fuel supply has reached a state where little or no delay can be accepted.
Minimum sector altitude (MSA)
The lowest altitude that will provide a minimum clearance of 1000 ft above all objects located in an area contained within a sector of a circle of 25 nm or 10 nm radius centred on a radio aid to navigation or, where there is no radio navigation aid, the aerodrome reference point.
Minimum vector altitude
The lowest altitude which a controller may assign to a pilot in accordance with the radar terrain clearance chart.
Missed approach holding Fix (MAHF)
A fix on an RNAV approach that marks the end of the missed approach segment and the point for the missed approach holding (where applicable).
Missed approach point (MAPT)
That point in an instrument approach procedure at or before which the prescribed missed-approach procedure must be initiated in order to ensure that the minimum obstacle clearance is not infringed.
Missed approach procedure (MAP)
The procedure to be followed if an approach cannot be continued.
Missed approach turning fix (MATF)
A fix on an RNAV approach that marks a turning point during the missed approach segment.
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).

N

NAIPS
The National Aeronautical Information Processing System, which provides briefings and flight notification functions.
Navigation specification
A set of aircraft and flight crew requirements needed to support performance-based navigation operations within a defined airspace. There are two kinds of navigation specifications:
RNP specification
A navigation specification based on area navigation that includes the requirement for performance monitoring and alerting, designated by the prefix RNP, for example RNP 4, RNP APCH.
RNAV specification
A navigation specification based on area navigation that does not include the requirement for performance monitoring and alerting, designated by the prefix RNAV, for example RNAV 5, RNAV 1.
Night
That period of time between the end of evening civil twilight and the beginning of morning civil twilight.
Non-controlled aerodrome
An aerodrome at which air traffic control is not operating. (Formerly designated non-towered)
Non-directional beacon (NDB)
A special radio station, the emissions of which are intended to enable a mobile station to determine its radio bearing or direction with reference to that special radio station.
NOTAM
Notice to airmen: a notice distributed by means of telecommunication containing information concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to personnel concerned with flight operations.
No-transgression zone (NTZ)
A corridor of airspace of defined dimensions located centrally between the two extended runway centre lines where controller intervention is required to manoeuvre aircraft when this airspace is penetrated by an aircraft conducting a simultaneous approach to a parallel instrument runway.

O

One-way route
A route with limitations for use in one direction, depicted on ERC-H, ERC-L and/or TAC charts by an arrow in the direction that can be used without limitation (see ERSA for additional details).
Operations manual
A manual provided by an operator for the use and guidance of operations staff, containing instructions as to the conduct of flight operations, including the responsibilities of its operations staff (refer CAR 215).
Operator
A person, organisation or enterprise engaged in or offering to engage  in aircraft operation.
Overshoot shear
A wind shear occurrence which produces an initial effect of overshooting the desired approach path and/or increasing airspeed.

P

Parking area
A specially prepared or selected part of an aerodrome within which aircraft may be parked.
Pavement classification number (PCN)
A number expressing the bearing strength of a pavement for unrestricted operations.
Performance-based navigation (PBN)
Area navigation based on performance requirements for aircraft operating along an ATS route, on an instrument approach procedure, or in a designated airspace. Note Performance requirements are expressed in navigation specifications (RNAV specification, RNP specification) in terms of accuracy, integrity, continuity, availability and functionality needed for the proposed operation in the context of a particular airspace concept.
Permissible all-up-weight
The weight to which an aircraft is limited by virtue of the physical characteristics of an aerodrome.
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.d
Precision approach procedure
An instrument approach procedure utilising azimuth and glide path information provided by ILS.
Precision runway monitor (PRM)
A surveillance radar system with a minimum azimuth accuracy of 0.06 degrees, an update period of 2.5 seconds or less, and a high resolution display providing position prediction and deviation alert, used in providing ILS course monitoring during independent approaches to runways separated by less than 1525 m.
Pre-departure clearance (PDC)
A means of delivering an unsolicited, text-based airways clearance to eligible aircraft via an ATC data link.
Preferred runway
A runway nominated by ATC or listed in the AIP as the most suitable for the prevailing wind, surface conditions or noise sensitive areas in the proximity of the aerodrome.
Primary means navigation system
A navigation system that, for a given operation or phase of flight,  must meet accuracy and integrity requirements, but need not meet full availability and continuity of service requirements. Safety is achieved by either limiting flights to specific time periods, or through appropriate procedural restrictions and operational requirements.
Procedural service
Term used to indicate that information derived from an ATS surveillance system is not required for the provision of ATS.
Procedure altitude/height
A specified altitude/height flown at or above the minimum altitude/height, and established to accommodate a stabilised descent at a prescribed descent gradient/angle in the intermediate/final approach segment.
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. This designation is appropriate only for reasons of defence.

Q

QNH altimeter setting
That pressure setting which, when placed on the pressure setting sub-scale of a sensitive altimeter of an aircraft located at the reference point of an aerodrome, will cause the altimeter to indicate the vertical displacement of the reference point above mean sea level.

R

Radar/ADS-B Information Service (RIS)
An on-request service provided to assist pilots of VFR flights, within ATS surveillance system coverage in Class E and Class G airspace, to avoid other aircraft or to assist in navigation.
Radio height
The radio altimeter reading which is equivalent to the OCA adjusted for terrain/obstacle profile.
Radio navigation service
A service providing guidance information or position data for the efficient and safe operation of aircraft supported by one or more radio navigation aids.
Rapid-exit taxiway
A taxiway connected to a runway at an acute angle and designed to allow landing aeroplanes to turn off at high relative speeds.
Receiver autonomous integrity monitoring (RAIM)
A system whereby an airborne GPS receiver/processor autonomously monitors the integrity of the navigation signals from GPS satellites.
Reduced vertical separation minimum (RVSM)
The vertical separation minimum of 1000 ft between FL290 and FL410 inclusive.
Repetitive flight plan
A flight plan referring to a series of frequently recurring, regularly operated individual flights with identical basic features, submitted by an operator for retention and repetitive use by ATS units.
Reporting point
A specified geographical location in relation to which the position  of an aircraft can be reported.
Required navigation performance (RNP)
A statement of the navigation performance necessary for operation within a defined airspace.
Rescue Coordination Centre (RCC)
A unit established 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.
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.
RNP type
A containment value expressed as a distance in nautical miles from  the intended position within which flights would be for at least 95 per cent of the total flying time.
Route
A way to be taken in flying from a departure to a destination aerodrome, specified in terms of track and distance for each route segment.
Runway (RWY)
A defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft.
Runway holding position
A designated position intended to protect a runway, an obstacle limitation surface, or an ILS critical/sensitive area at which taxiing aircraft and vehicles must stop and hold, unless otherwise authorised by the aerodrome control tower.
Runway number
The runway identification associated with the runway direction end.
Runway strip
The defined area, including the runway (and stopway if provided), intended to reduce the risk of damage to aircraft inadvertently running off the runway and to protect aircraft flying over it during take-off, landing or missed approach.
Runway visibility (RV)
The distance along a runway over which a person can see and recognise a visibility marker or runway lights.
Runway visual range (RVR)
The range over which the pilot of an aircraft on the centre line of a runway can see the runway surface markings or the lights delineating the runway or identifying its centre line. (ICAO)

S

SARTIME
The time nominated by a pilot for the initiation of SAR action if an arrival report has not been received by the appropriate authority.
SARWATCH
A generic term covering SAR alerting based either on full position reporting procedures, scheduled reporting times (SKEDS), or SARTIME.
Search and rescue (SAR)
The act of finding and returning to safety, aircraft and persons involved in an emergency phase.
Search and rescue region (SRR)
The specified area within which search and rescue is coordinated by a particular rescue coordination centre.
Segment minimum safe altitude
The lowest altitude at which the minimum obstacle clearance is provided.
Segregated parallel operations
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.
Significant point
A specified geographical location used in defining an ATS route or the flight path of an aircraft and for other navigation and ATS purposes.
Significant weather
Any weather phenomenon which might affect flight visibility or present a hazard to an aircraft.
Simultaneous Opposite Direction Parallel Runway Operations (SODPROPS)
A condition whereby arriving aircraft will approach and land on one runway, concurrent with aircraft departures from the parallel runway in the opposite direction to that being used for approach and landing.
Situation display
An electronic display depicting the position and movement of aircraft and other information as required.
Sole-means navigation system
A navigation system that, for a given phase of flight, must allow the aircraft to meet all four navigation system performance requirements – accuracy, integrity, availability and continuity of service.
SSR code
The number assigned to a particular multiple-pulse reply signal transmitted by a transponder in Mode A or Mode C.
Standard Instrument Arrival (STAR)
A designated IFR arrival route linking a significant point, normally on an ATS route, with a point from which a published instrument approach procedure can be commenced.
Standard Instrument Departure (SID)
A designated IFR departure route linking the aerodrome or a specified runway of the aerodrome with a specified significant point, normally on a designated ATS route, at which the en route phase of a flight commences.
Standard pressure
The pressure of 1013.2 HPa which, if set up on the pressure sub-scale of a sensitive altimeter, will cause the latter to read zero when at mean sea level in a standard atmosphere.
Standard pressure region
Airspace above 10,000 ft where the sub-scale of a pressure-sensitive altimeter is set to 1013.2 HPa.
Stopway
A defined rectangular area on the ground at the end of the take-off run prepared as a suitable area in which an aircraft can be stopped in the case of an abandoned take-off.
Supplemental means navigation system
A navigation system that must be used in conjunction with a sole-means navigation system.

T

Tactical Air Navigation (TACAN)
An ultra-high frequency navigation aid which provides a continuous indication of bearing and slant range, in nautical miles, to the selected ground station.
Taxiway (TWY)
A defined path on a land aerodrome established for the taxiing of aircraft and intended to provide a link between one part of the aerodrome and another.
Terrain clearance
The vertical displacement of an aircraft’s flight path from the terrain.
Threshold
The beginning of that portion of the runway usable for landing.
Threshold crossing height
The height of the ILS glide path at the threshold.
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 arrival over the destination aerodrome.
Touch-and-go landing
A procedure whereby an aircraft lands and takes off without coming to a stop.
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 north (true, magnetic or grid).
Transitional surface
An inclined plane associated with the runway strip and the approach surfaces.
Transition altitude
The altitude at or below which the vertical position of an aircraft is controlled by reference to altitudes.
Transition layer
The airspace between the transition altitude and the transition level.
Transition level
The lowest flight level available for use above the transition altitude.
Transponder
A receiver/transmitter which will generate a reply signal upon proper interrogation; the interrogation and reply being on different frequencies.

U

Unalerted see-and-avoid
A procedure where flight crew, who have no specific knowledge of other aircraft in their vicinity, rely solely on their ability to physically see and avoid colliding with aircraft that may be in their vicinity.
Undershoot shear
A wind shear occurrence which produces an initial effect of undershooting the desired approach path and/or decreasing air speed.
Universal Communications (UNICOM)
A non-ATS communications service provided to enhance the value of information normally available about a non-controlled aerodrome.
Unserviceable area
A portion of the movement area not available for use by aircraft because of the physical condition of the surface, or because of any obstruction  on the area.

V

Vectoring
Provision of navigational guidance to aircraft in the form of specific headings, based on the use of an ATS surveillance system.
VFR climb and descent
ATC authorisation for an IFR flight in VMC, at or below FL180, in Classes D and E airspace, to conduct a visual climb or descent.
VFR-on-top
ATC authorisation for an IFR flight to operate in VMC, at or below FL180, in Class E airspace at any appropriate VFR altitude or flight level (in accordance with ENR 1.2 Section 2, ENR 1.7 Section 5. and as restricted by ATC).
VHF Omni-directional Radio Range (VOR)
A VHF radio navigational aid which provides a continuous indication of bearing from the selected VOR ground station.
Visibility
Visibility for aeronautical purposes is the greater of:
  • the greatest distance at which a black object of suitable dimensions, situated near the ground, can be seen and recognised when observed against a bright background or
  • the greatest distance at which lights of about 1000 candelas can be seen and identified against an unlit background.
Visual (ATC usage)
used by ATC to instruct a pilot to see and avoid obstacles while conducting flight below the MVA or MSA/LSALT.
Visual (pilot usage)
used by a pilot to indicate acceptance of responsibility to see and avoid obstacles while operating below the MVA or MSA/LSALT.
Visual approach slope indicator system (VASIS)
A system of lights so arranged as to provide visual information to pilots on approach of their position in relation to the optimum approach slope for a particular runway.
VS1G
The one-G stall speed at which an aeroplane can develop a lift force (normal to the flight path) equal to its weight.

W

Way point
A specified geographical location used to define an area navigation route or the flight path of an aircraft employing area navigation. Way points are identified as either:
  • Fly-by way point – A way point which requires turn anticipation to allow tangential interception of the next segment of a route or procedure, or
  • Flyover way point – A way point at which a turn is initiated in order to join the next segment of a route or procedure.
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