GEN 2.3 DEFINITIONS USED
ADVISORY ROUTE
A designated route along which air traffic advisory service is available.
AERODROME (AIRFIELD)
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 REFERENCE POINT
The designated geographical location of the Aerodrome.
AERODROME TRAFFIC
All traffic on the manoeuvring area of an aerodrome and all aircraft flying in the vicinity of an aerodrome, within the CTR.
AERODROME TRAFFIC CIRCUIT
The specified path to be flown by aircraft operating in the vicinity of an aerodrome, inside the CTR.
The picture below indicates a left hand circuit. A right hand circuit is exactly the same except all turns are now to the right.
AERODROME TRAFFIC ZONE
An airspace of defined dimensions established around an aerodrome for the protection of aerodrome traffic.
AERONAUTICAL INFORMATION REGULATION AND CONTROL (AIRAC)
A system aimed at advance notification based on common effective dates, of circumstances that necessitate significant changes in operating procedures, i.e. navigation, airspaces & operations.
AIRWAY
A control area or portion thereof established in the form of a corridor equipped with radio navigation aids. Its name is starts with a letter, usually A, R, W followed by a number. If the name is preceded by a U it is an Upper airway. If the route name is followed by a D it is an Advisory route.
AIR TRAFFIC CONTROL SERVICE
A service provided for the purpose of:
a) Preventing collisions between aircraft:
i) in the air,
ii) on the manoeuvring area,
iii) and obstructions on the manoeuvring area, and
b) Expediting and maintaining an orderly flow of air traffic.
AIR TRAFFIC SERVICE UNIT
An unit consisting of 1 or more ATCs established for the provision of an Air Traffic Control service.
ALTERNATE AERODROME
An aerodrome to which an aircraft may proceed when it becomes either impossible or inadvisable to proceed to land at the aerodrome of intended landing.
ALTITUDE
An aircraft’s vertical distance above MSL where the distance is related to the local pressure at the aerodrome. Used below the Transition Altitude, within 25nm from an aerodrome.
APPROACH CONTROL
An ATC service to controlled flights arriving at, or departing from, one or more aerodromes. Approach control is responsible for all aircraft inside a TMA and sometimes the CTA depending on the airspace design.
APRON
A defined area, on a land aerodrome intended to accommodate aircraft for the purpose of loading or unloading passengers, mail or cargo, fuelling, parking or maintenance.
AREA CONTROL
An ATC service to controlled flights in controlled airspace and advice and information to other flights under its jurisdiction. The control service is provided to aircraft en-route between the departure and destination aerodrome and during the latter part of the climb and initial part of descent. The Area controller also does the initial sequencing of aircraft inbound to the same TMA for the Approach controller(s).
ATC CLEARANCE
Authorisation for an aircraft to proceed under conditions specified by an ATSU.
ATIS (Automatic Terminal Information Service)
A system providing current, routine information to arriving and departing aircraft by means of continuous and repetitive broadcasts throughout the day or a specified portion of the day. E.g. current weather conditions, runway-in-use, etc.
ATS Route
A specific route designed for channelling the flow of air traffic as necessary for the provision of air traffic services. The term is used to mean variously SID, STAR, Airway or RNAV.
BLIND TRANSMISSION
A transmission from one station to another station in circumstances where 2-way communication cannot be established but where it is believed that the called station is able to receive the transmission.
BROADCAST
A transmission of information relating to air navigation that is not addressed to a specific station or stations.
CLEARANCE DELIVERY
An ATC service providing aircraft, wanting to depart, with departure clearances. Established when Ground Control communications is too congested to provide departure clearances as well.
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.
CODE (SSR or SQUAWK CODE)
The 4-digit number assigned to a particular multiple pulse reply signal transmitted by a transponder. Contains digits 0 to 7.
CONTROLLED AIRSPACE
An airspace of defined dimensions within which an air traffic control service is provided to IFR and VFR flights in accordance with the airspace’s classification. E.g. CTRs, TMAs, CTAs, UTAs, RNAV routes & Airways.
CONTROL AREA
A controlled airspace extending upwards from a specified limit above the earth. Usually found above a TMA and usually controlled by an Area Control unit.
CONTROL ZONE
A controlled airspace extending upwards from the surface of the earth to a specified upper limit. Established around an aerodrome for the protection of aerodrome traffic. Do not confuse with Center (_CTR), a term used for the callsign of an Area unit on IVAO.
DANGER AREAS
An airspace of defined dimensions within which activities dangerous to the flight of aircraft may exist at specified times.
In South Africa all danger areas area indicated on aviation maps as follows FADxxx. FA is the ICAO indicator for South Africa, D indicating a Danger area and then followed by 3 numbers to identify each one separately.
DECISION ALTITUDE/HEIGHT
A height/altitude above the highest elevation in the touchdown zone, specified for a glide slope approach, at which a missed-approach procedure must be initiated if the required visual reference has not been established.
DEPARTURE CONTROL
An ATC service to controlled flights departing from an aerodrome. Not used in RSA at the moment. This unit is responsible for aircraft departing from an aerodrome.
DISTANCE MEASURING EQUIPMENT
A facility usually found with a VOR or ILS. It responds to radio waves from an aircraft’s onboard DME equipment. The onboard equipment thus determines the distance between an aircraft and that facility. Measured in nautical miles.
ELEVATION
The vertical distance of a point or a level, on or affixed to the surface of earth, measured from AGL. Measurements are always in feet.
ESTIMATED ELAPSED TIME
The estimated time required to proceed from one point to another. Used in a flight plan to indicate the duration of a flight or time from departure to crossing a FIR boundary.
ESTIMATED TIME OF ARRIVAL
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 or aerodrome.
For VFR flights, the time at which it is estimated that the aircraft will arrive over the aerodrome.
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 landing.
FINAL APPROACH
That portion of the aerodrome circuit where the aircraft is positioned with the runway of intended landing directly ahead relative to the direction of flight.
FINAL APPROACH FIX
The point at which a published instrument approach begins.
FLIGHT INFORMATION REGION
An airspace of defined dimensions within which flight information service is provided.
FLIGHT INFORMATION SERVICE
A service provided for the purpose of giving advice and information useful for the safe and efficient conduct of flights.
FLIGHT LEVEL
An aircraft’s vertical distance above MSL where the distance is related to 1013.2hPA. Used from the Transition Level and above, outside 25nm from an aerodrome or where the local air pressure is not known. Written as FLxxx / FL080.
FLIGHT PLAN
Specified information provided to an ATSU relative to the intended flight or portion of a flight of an aircraft.
GLIDE PATH
A descent profile defined for vertical guidance during a final approach.
GROUND (MOVEMENT) CONTROL
This forms part of Aerodrome Control. A Ground controller controls all traffic on the manoeuvring area, excluding the active runway(s).
HANDOFF
The transfer of ATC service & communications with an aircraft from one controller to the next.
HEADING
The direction in which the nose of an aircraft is pointed. Always expressed in Magnetic degrees.
HEIGHT
The vertical distance of object or point measured from a specific datum, usually the ground.
HOLDING POINT
Visual holding point:
A point on a taxiway intersecting with a runway approx. 50m from the runway. Indicated by means of yellow lines across the width of the taxiway. Can only be used when the CTR is VMC.
CAT xx holding point:
A point on a taxiway intersecting a runway approx. 100m from the runway. Indicated by yellow lines across the width of the taxiway. This is to position aircraft clear of the ILS sterile area. Must be used when the CTR is IMC, can be used during VMC conditions, if necessary.
HOLDING PROCEDURE
A pre-determined manoeuvre which keeps an aircraft within a specified airspace while awaiting further clearance.
INDICATED AIR SPEED
The speed of an aircraft relative to the air around it. Measured in knots (kts). This value is very important to pilots as this determines when gear can go up or down, flap settings, stall speed, etc.
INITIAL APPROACH FIX
Instrument: That part of an instrument approach procedure in which the aircraft has departed an IAF or point and is manoeuvring to enter the intermediate or final approach. It ends at the IF or point or, where no intermediate segment is established, at the FAF or point.
Visual: That part of a visual approach of an aircraft immediately prior to arrival over the airfield of destination, or over the reporting point from which the final approach to the airfield is commenced.
INSTRUMENT FLIGHT RULES
A flight where the pilot navigates the aircraft referring to instruments only, using land based navigational aids and satellites.
INSTRUMENT LANDING SYSTEM
A land based system to guide aircraft onto a runway. It consists of a localiser guiding the aircraft laterally (left/right) and a glide slope/path guiding the aircraft vertically.
The localiser, placed at the opposite end of the runway, sends out a radio beam that aircraft’s navigation equipment receives and indicates to the pilot where the aircraft is laterally, relative to the runway.
The glide slope, placed next to the touchdown point of the runway, also sends out a radio beam that the aircraft’s navigation equipment receives and indicates to the pilot where the aircraft is vertically relative to the glide path for descend.
A third component, indicates to the pilot the distance from the runway. It can either be a fixed navigation aid called an Outer Marker (OM), which is usually an NDB. An OM is placed usually approx. 4nm from the edge of the runway. More modern ILS systems are doing away with the OM and use a DME. The latter is much better as it gives the pilot a constant exact distance from the runway where as the OM can only give one fixed distance one time, only when the aircraft is overhead the OM.
The ILS is usually only received by an aircraft from within approx. 25nm. The ILS frequency is a published frequency for the particular aerodrome’s runway it serves. Each ILS within relative close proximity has a different frequency to prevent an aircraft from receiving 2 ILS systems at the same time. This frequency is set on an aircraft’s NAV radio. The frequency range is within 108.00MHz to 117.90MHz.
An ILS is classified according to its accuracy, backup power, approach lighting and various other facilities. For ‘virtual’ simulation we are only concerned with its accuracy, which isn’t really simulated either as far as the author is aware of. These are the categories:
|
Category |
Vertical visibility (ft) |
Horizontal visibility (m) |
|
I |
200 |
600 |
|
II |
100 |
350 |
|
IIIa |
50 |
100 |
|
IIIb |
0 |
50 |
|
IIIc |
0 |
0 |
INSTRUMENT METEOROLOGICAL CONDITION
Meteorological conditions expressed i.t.o. visibility, distance from cloud and ceiling, less than the minima specified for VMC. Exists when horizontal visibility is 5000m or below OR cloud ceiling is 1500ft or below.
INTERMEDIATE FIX
That part of an instrument approach procedure in which aircraft configuration, speed, and positioning adjustments are made. It blends the initial approach segment into the final approach segment. It begins at the IF or point and ends at the FAF.
INTERSECTION
An intersection is a fictional navigational fix. Its name consists usually of 5 characters. The position of an intersection is determined by latitude and longitude. It is also referred to as a fix or position.
LATITUDE
Latitude is an angular measurement ranging from 0° at the Equator to 90° at the poles. Each degree of latitude is further sub-divided into 60 minutes, each of which divided into 60 seconds. A latitude is thus specified as N or S00°00′00″. E.g. S33°19′42″. For high accuracy, the seconds could be specified with a decimal fraction.
LOCALISER
A localiser is one component of an ILS. The localiser usually provides runway centreline guidance to aircraft. In some cases a localiser is at an angle to the runway usually due to obstructions around the airport. Localisers also exist in stand alone instrument approach installations and are not always part of an ILS or Instrument Landing System.
LONGITUDE
Longitude, describes the location of a place on Earth East or West of a North-South line called the Prime Meridian. Longitude is given as an angular measurement ranging from 0° at the Prime Meridian to +180° eastward and −180° westward. Each degree of longitude is further sub-divided into 60 minutes, each of which divided into 60 seconds. A longitude is thus specified as E or W000°00’00. E.g. E123°27′30″
MANOEUVRING AREA
That part of an aerodrome to be used for the take-off, landing and taxiing of aircraft, excluding aprons.
MEAN SEA LEVEL
A reference datum used to calculate altitude, height or elevation. Measured from the average level of the sea.
METEOROLOGICAL REPORT
This is a report formulated by the weather office. It is distributed usually half hour or possibly hour depending on the aerodrome which is intended for. Most aerodromes receive a METAR every half hour.
Wind on a station’s METAR is always in True degrees, thus the station’s magnetic variation must be added or subtracted to obtain magnetic degrees.
In South Africa we add an avg. of 20 degrees at all stations.
MISSED APPROACH POINT
The point of a published ILS approach expressed in time and distance from the FAF, or as an altitude on the glide slope, at which the missed approach procedure must be initiated if the runway or approach lights are not clearly in sight.
MOVEMENT AREA
That part of an aerodrome to be used for the take-off, landing and taxiing of aircraft, including aprons.
NAVIGATION(AL) AIDS
Navigation aids are terrestrial (ground based) or celestial (airborne) facilities to assist aircraft with determining the aircrafts position. The aids can either be a VOR, NDB, DME or ILS. The celestial facilities being satellites providing a position with latitude/longitude to aircraft.
NON-DIRECTIONAL BEACON
A radio beacon transmitting non-directional signals whereby the pilot of an aircraft equipped with direction-finding equipment can determine his or her bearing to or from the radio beacon and “home” on or track to or from the station. When the NDB is installed in conjunction with an ILS marker, it is normally called a marker beacon, e.g. an OM. An aircraft needs to be fitted with an ADF receiver. The frequency range is approximately 190 – 435 & 510 – 535 kHz.
NOTICE TO AIRMEN
A notice distributed by means of telecommunications 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.
OBSTACLE CLEARANCE ALTITUDE/HEIGHT
The lowest height/altitude above the elevation of the relevant runway threshold or above the aerodrome elevation, as applicable, used in establishing compliance with appropriate obstacle clearance criteria.
ONWARD CLEARANCE TIME
An OCT is the time at which an aircraft which has been instructed to hold during the en-route phase of flight is cleared to resume its flight.
OUTER MARKER
Most ILS and localiser approaches incorporate at least one marker and as many as three. What is referenced as the “Outer Marker” is anywhere from four to ten miles from the threshold of the runway and normally provides the IAF. When flying overhead the OM, the OM lamp should be lit and coloured blue.
PRECISION APPROACH PATH INDICATOR
A device consisting of 2 (APAPI) or 4 (PAPI) lights positioned abeam the touchdown zone of the runway. Each light shows individually either red or white. The combination of colours displayed, indicating to a pilot his position vertically from the ideal glide path or approach slope. In this example the PAPI is on the right hand side of the runway, thus the light closest to the runway is on the left. It works as follows:
To see what the APAPI looks like or indicates, only use the six lights in the middle of the above drawing.
PROHIBITED AREA
An airspace of defined dimensions, above land areas or territorial waters of a state, within which the flight of any aircraft is prohibited. In South Africa all prohibited areas area indicated on aviation maps as follows FAPxxx. FA is the ICAO indicator for South Africa, P indicating a Prohibited area and then followed by 3 numbers to identify each one.
RADAR (RAdio Detection And Ranging)
Used in REAL aviation to determine the position and altitude of an aircraft by means of radio waves. Two types of Radars exist, namely Primary and Secondary.
Primary Radar emits a very high powered radio wave and listens (receives) echos of an aircraft’s body. Thereby calculating the aircraft’s distance and direction only, NOT altitude.
Secondary Radar emits a lower powered radio wave. All aircraft fitted with a transponder that receives this radio wave, responds with a code, namely the Squawk/SSR code if a Mode A transponder or a Squawk code and altitude if a Mode C transponder. The altitude is read from the aircraft’s altimeter. A more advanced Mode S exists today, transmitting a lot more information about the aircraft back to the RADAR.
For flight simulation purposes we do not make use of radar, but merely a form of positioning by Latitude and Longitude to determine aircraft position onto our virtual radar screen, IvAc.
RADAR CONTACT
The situation which exists when the radar blip or radar position symbol of a particular aircraft is seen and identified on a radar display.
RADAR CONTROL
Term used to indicate that radar-derived information is employed directly in the provision of air traffic control service.
RADAR HANDOVER
Transfer of responsibility for the control of an aircraft between two controllers using radar following identification of the aircraft by both controllers.
RADAR IDENTIFICATION
The process of correlating a particular radar blip or radar position symbol with a specific aircraft.
RADIAL
A magnetic bearing extending from a VOR/VORTAC/TACAN.
REPORTING POINT
A specified geographical location in relation to which the position of an aircraft can be reported.
RESTRICTED AREA
An airspace of defined dimensions, above land areas or territorial waters of a state, within which the flight of any aircraft is restricted in accordance with certain conditions.
In South Africa all restricted areas area indicated on aviation maps as follows FARxxx. FA is the ICAO indicator for South Africa, R indicating a Restricted area and then followed by 3 numbers to identify each one.
RUNWAY
A defined rectangular area, on a land aerodrome prepared for the landing and take-off of aircraft.
RUNWAY VISUAL RANGE
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.
SPECI
A SPECI report replaces the last METAR reported for that station. It is published when there has been adverse weather changes to the last report.
SPECIAL VFR
A VFR flight cleared by air traffic control to operate within a control zone under meteorological conditions below the visual meteorological conditions.
SQUAWK CODE
It is a code consisting of 4 digits all from 0 to 7. This code is entered into a transponder and is broadcasted by the transponder when interrogated by a Secondary surveillance Radar. ATC uses this code to uniquely identify aircraft on a Radar screen.
STANDARD INSTRUMENT DEPARTURE
A published procedure or route, an departing IFR aircraft must fly when cleared to do so. A SID starts at the runway and terminates at a VOR, NDB or intersection. The name of the SID is the name of that termination facility followed by a number and letter, e.g. OKTED 1C. It is used at busy airfields to lessen the workload for the ATC and create structured routings.
STANDARD TERMINAL ARRIVAL ROUTE
A published procedure or route an arriving IFR aircraft must fly when cleared to do so. A STAR starts at a VOR, NDB or intersection and terminates on final approach at the runway or close to it when RADAR vectors by ATC to final approach is required. The name of the STAR is the name of the facility where it starts followed by a number and letter, e.g. WOLSELEY 4C. It is used at busy airfields to lessen the workload for the ATC and create structured routings.
STOPWAY
A defined rectangular area on the ground, at the end of the take-off run available, prepared as a suitable area in which an aircraft can be stopped in the case of an abandoned take-off.
TAXIING
Movement of an aircraft on the surface of an aerodrome under its own power, excluding take-off and landing, but including, in the case of helicopters, operation over the surface of an aerodrome within a height band associated with ground effect and at speeds associated with taxiing, i.e. air-taxiing.
TAXIWAY
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. E.g. Between the aprons and runways.
TERMINAL CONTROL AREA
A control area normally established at the confluence of ATS routes in the vicinity of one or more major aerodromes. The TMA is usually controlled by the Approach, Departure controller(s) and could also be an Area controller.
TIME
UTC (Universal Time Constant) and the 24-hour clock will be used at all times. UTC is the same time as GMT (Greenwich Mean Time). The world is divided into 24 time zones (for 24 hours) and a letter indicating a specific time zone, letters J and N not used. UTC time is zone Zulu. Thus we refer too 1800Z time. If you have to refer to local South African time, it’s indicated followed by Bravo, 2000B. Aviation always uses Zulu time around the world to simplify things.
TOUCHDOWN
The point where the nominal glide path intercepts the runway.
TOWER CONTROL
This forms part of Aerodrome Control. A Tower controller controls all traffic on the active runway(s) and all airborne aircraft within the CTR.
TRACK
The projection on the earth’s surface of the path of an aircraft, direction of which the path at any point is usually expressed in degrees from North (true, magnetic or grid)
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.
TRANSITION ALTITUDE
This is a fixed, published altitude for every aerodrome. It is published on the SID, STAR and other charts for that aerodrome. The Transition Altitude is the altitude at which a climbing aircraft’s altimeter setting (barometric pressure) is changed from the local QNH to QNE (1013.2hPa). At or below the TA the pilot flies at altitude indicated in thousands of feet. When given climb or descend to an altitude, ATC must provide the local QNH.
TRANSITION LEVEL
This is a level calculated according to the local QNH, usually provided by ATC or via the ATIS. The Transition Level is the Level at which a descending aircraft’s altimeter setting (barometric pressure) is changed from QNE (1013.2hPA) to the local QNH. At or above the TL the pilot flies at Flight Levels.
TRANSPONDER
A receiver/transmitter which will generate a reply signal upon proper interrogation (the interrogation and reply being on different frequencies).
UPPER CONTROL AREA
A defined controlled airspace extending upwards from a specified limit above the earth. Usually found above a CTA and controlled by an Area Control unit. This airspace will always be Class A.
VFR FLIGHT
A flight conducted in accordance with the visual flight rules.
VISIBILITY
Visibility for aeronautical purposes is the greater of :-
a) 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;
b) the greatest distance at which lights in the vicinity of 1000 candelas can be seen and identified against an unlit background.
VISUAL APPROACH
An approach by an IFR flight when either part or all of an instrument approach procedure is not completed and the approach is executed with visual reference to terrain.
VISUAL FLIGHT RULES
A flight where the pilot navigates the aircraft with reference to the terrain, using mountains, roads, railway tracks, etc and aviation maps. Inside controlled airspace VFR aircraft can be cleared to altitudes or Flight Levels but any other navigation must be done by referring to positions on the ground or the aerodrome circuit.
VISUAL METEOROLOGICAL CONDITION
Meteorological conditions expressed in terms of visibility, horizontal and vertical distance from cloud ceiling, equal to or better than the specified minima. When horizontal visibility is at or above 5000m and or cloud ceiling is at or above 1500ft the zone is VMC.
VHF OMNI-DIRECTIONAL RADIO-RANGE
A type of radio navigation beacon for aircraft. VORs broadcast a VHF radio signal encoding both the identity of the station and the angle to it, telling the pilot in what direction he lies from the VOR station, referred to as the radial. Comparing two such measurements on a chart allows for a fix. In many cases the VOR stations have a co-located DME to provide distance measurement allowing for a one-station fix. Most aircraft are fitted with a navigation radio that can tune onto the VOR frequency. VOR frequency range is 108.00MHz. to 117.90MHz.
WAYPOINT
A specified geographical location used to define an area navigation route or the flight path of an aircraft employing area navigation.