Glossary of Terms


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1

1 in 60 Rule

The 1 in 60 rule is a rule of thumb used in air navigation, and states that if a pilot has travelled sixty miles then an error in track of 1 nm is approximately a 1° error. It is based on the small-angle approximation. In reality the error is 0.96° but this difference is trivial in air navigation.

You can also use the 1 in 60 rule to approximate your distance from a VOR by flying 90 degrees to a radial and timing how long it takes to fly 10 degrees. The time in seconds divided by 10 is roughly equal to the time in minutes from the station at your current speed.


A

ABAS

Aircraft-based augmentation system

An augmentation system which augments and/or integrates the information obtained from the other GNSS elements with information available on board the aircraft.


Abortive Start

‘Abortive Start’ (turbine engines) means an attempt to start, in which the engine lights up, but fails to accelerate.


Accessory drives

‘Accessory drives’ means any drive shaft or utility mounting pad, furnished as a part of the auxiliary power unit, that is used for the extraction of power to drive accessories, components, or controls essential to the operation of the auxiliary power unit or any of its associated systems.


Accident

Accident. An occurrence associated with the operation of an aircraft which, in the case of a manned aircraft, takes place
between the time any person boards the aircraft with the intention of flight until such time as all such persons have
disembarked, or in the case of an unmanned aircraft, takes place between the time the aircraft is ready to move with the
purpose of flight until such time as it comes to rest at the end of the flight and the primary propulsion system is shut down,
in which:


a) a person is fatally or seriously injured as a result of:
— being in the aircraft, or
— direct contact with any part of the aircraft, including parts which have become detached from the aircraft, or
— direct exposure to jet blast,
except when the injuries are from natural causes, self-inflicted or inflicted by other persons, or when the injuries are to
stowaways hiding outside the areas normally available to the passengers and crew; or


b) the aircraft sustains damage or structural failure which:
— adversely affects the structural strength, performance or flight characteristics of the aircraft, and
— would normally require major repair or replacement of the affected component,
except for engine failure or damage, when the damage is limited to a single engine, (including its cowlings or
accessories), to propellers, wing tips, antennas, probes, vanes, tires, brakes, wheels, fairings, panels, landing gear
doors, windscreens, the aircraft skin (such as small dents or puncture holes), or for minor damages to main rotor
blades, tail rotor blades, landing gear, and those resulting from hail or bird strike (including holes in the radome); or


c) the aircraft is missing or is completely inaccessible

.
Note 1.— For statistical uniformity only, an injury resulting in death within thirty days of the date of the accident is
classified, by ICAO, as a fatal injury.


Note 2.— An aircraft is considered to be missing when the official search has been terminated and the wreckage has not
been located.


Note 3.— The type of unmanned aircraft system to be investigated is addressed in ICAO Annex 13, 5.1.


Note 4.— Guidance for the determination of aircraft damage can be found in ICAO Annex 13, Attachment G.


Accredited representative

Accredited representative. A person designated by a State, on the basis of his or her qualifications, for the purpose of
participating in an investigation conducted by another State. Where the State has established an accident investigation
authority, the designated accredited representative would normally be from that authority.


ACD

A.C.D. - Additional Control Device


ACN

Aircraft classification number (ACN). A number expressing the relative effect of an aircraft on a pavement for a specified
standard subgrade category.
Note.C The aircraft classification number is calculated with respect to the center of gravity (CG) position which yields the
critical loading on the critical gear. Normally the aftmost CG position appropriate to the maximum gross apron (ramp) mass
is used to calculate the ACN. In exceptional cases the forwardmost CG position may result in the nose gear loading being
more critical.


Acrobatic flight

“acrobatic flight” means manoeuvres intentionally performed by an aircraft involving an
abrupt change in its attitude, an abnormal attitude, or an abnormal variation in speed


Acts of unlawful interference

Acts of unlawful interference. These are acts or attempted acts such as to jeopardize the safety of civil aviation, including but
not limited to:
• unlawful seizure of aircraft,
• destruction of an aircraft in service,
• hostage-taking on board aircraft or on aerodromes,
• forcible intrusion on board an aircraft, at an airport or on the premises of an aeronautical facility,
• introduction on board an aircraft or at an airport of a weapon or hazardous device or material intended for criminal
purposes,
• use of an aircraft in service for the purpose of causing death, serious bodily injury, or serious damage to property or the
environment,
• communication of false information such as to jeopardize the safety of an aircraft in flight or on the ground, of
passengers, crew, ground personnel or the general public, at an airport or on the premises of a civil aviation facility.


ADIZ

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


Admission

Admission. The permission granted to a person to enter a State by the public authorities of that State in accordance with its
national laws.


ADS Agreement

“ADS Agreement” means an ADS reporting plan which establishes the conditions of ADS
data reporting


Advisory airspace

“advisory airspace” means advisory areas or advisory routes


Advisory area

“advisory area” means an area designated by the appropriate ATS authority within a flight
information region where an Air Traffic Advisory Service is available


Aerodrome

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.


Aerodrome climatological summary

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


Aerodrome control tower

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


Aerodrome elevation

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


Aerodrome identification sign

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


Aerodrome operating minima

“aerodrome operating minima” means the limits of usability of an aerodrome for:


(i) take-off, expressed in terms of runway visua l range (RVR) and/or visibility
and if necessary, cloud conditions; or


(ii) landing in approach and landing operations with vertical guidance, expressed
in terms of visibility and/or runway visual range (RVR) and decision height or
altitude (DA/H); and

(iii) landing in non-precision approach and landing operations, expressed in terms
of visibility and/or runway visual range, minimum descent altitude or height
(MDA/H) and if necessary, cloud conditions;


Aerodrome reference point

Aerodrome reference point. The designated geographical location of an aerodrome.


Aerodrome traffic density

Aerodrome traffic density.
a) Light. Where the number of movements in the mean busy hour is not greater than 15 per runway or
typically less than 20 total aerodrome movements.


b) Medium. Where the number of movements in the mean busy hour is of the order of 16 to 25 per runway or
typically between 20 to 35 total aerodrome movements

.
c) Heavy. Where the number of movements in the mean busy hour is of the order of 26 or more per runway or
typically more than 35 total aerodrome movements.


Note 1.C The number of movements in the mean busy hour is the arithmetic mean over the year of the number of
movements in the daily busiest hour.


Note 2.C Either a take-off or a landing constitutes a movement.


Aeronautical beacon

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


Aeronautical chart

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


Aeronautical ground light

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


Aeronautical operational control

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


Aeroplane reference field length

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


Note.C ICAO Annex 14, Attachment A, Section 2 provides information on the concept of balanced field length.


AES

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

Ground earth station (GES). An earth station in the fixed satellite service, or, in some cases, in the aeronautical
mobile-satellite service, located at a specified fixed point on land to provide a feeder link for the aeronautical mobilesatellite
service.

Note.— This definition is used in the ITU’s Radio Regulations under the term “aeronautical earth station”. The
definition herein as “GES” for use in the SARPs is to clearly distinguish it from an aircraft earth station (AES), which is a
mobile station on an aircraft.


Afterburning

Afterburning. A mode of engine operation wherein a combustion system fed (in whole or part) by vitiated air is used.


AFTN

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


AIP

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

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


Air operator’s certificate

“air operator’s certificate” (AOC) means a certificate authorising an operator to
carry out specified commercial air transport operations.


Air traffic

“air traffic” means all aircraft in flight or operating on the manoeuvring area of an
aerodrome.


Air traffic advisory service

“air traffic advisory service” means a service provided by the appropriate ATS authority
within advisory airspace to ensure separation, in so far as practical, between aircraft which
are operating on IFR flight plans.


Air traffic control clearance

“air traffic control clearance” means authorisation for an aircraft to proceed under
conditions specified by an air traffic control unit. The term may be abbreviated to
“clearance” and may be prefixed by the word “taxi”, “take-off”, “departure”, “en-route”,
“approach”, or “landing”, to indicate the particular portion of flight to which the air traffic
control clearance relates;


Air traffic control service

“air traffic control service” means a service provided for the purpose of:

(a) preventing collisions between aircraft, and on the manoeuvring area, between
aircraft and obstructions, and


(b) expediting and maintaining an orderly flow of air traffic.


Air traffic service

“air traffic service” (ATS) includes the following services, namely, flight information
service, alerting service, air traffic advisory service, air traffic control service, area control
service, approach control service and aerodrome control service.


Air traffic services airspaces

“air traffic services airspaces” means airspaces of dimensions defined and alphabetically
designated by the appropriate ATS authority within which specific types of flights may
operate and for which air traffic services and rules of operation are specified.


Air traffic services reporting office

“air traffic services reporting office” means a unit provided by the appropriate authority
either as a separate unit or combined with another unit, for the purpose of receiving reports
concerning air traffic services and flight plans submitted before departure.


Air transit route

Air transit route. A defined route for the air transiting of helicopters.


Air transport undertaking

“air transport undertaking” means an undertaking the business of which includes the
carriage by air for hire or reward of passengers or cargo;


Air-ground communication

“air-ground communication” means a two-way communication between aircraft and
stations or locations on the surface of the earth;


Air-ground control radio station

“air-ground control radio station” means an aeronautical telecommunication station having
primary responsibility for handling communications pertaining to the operation and control
of aircraft in a given area;


Air-report

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


Note.— Details of the AIREP form are given in the PANS-ATM (Doc 4444).


Air-taxiing

“air-taxiing” means the movement of a helicopter above the surface of an aerodrome,
normally in ground effect and at a speed normally less than 37 km/h (20 kt)


AIRAC

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


Airborne collision avoidance system

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


Aircraft address

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


Aircraft equipment

Aircraft equipment. Articles, including first-aid and survival equipment and commissary supplies, but not spare parts or
stores, for use on board an aircraft during flight


Aircraft observation

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


Aircraft operating manual

“aircraft operating manual” means a manual, acceptable to the state of the operator,
containing normal, abnormal and emergency procedures, checklists, limitations,
performance information, details of the aircraft systems and other material relevant
to the operation of the aircraft. This manual is part of the Operations Manual
defined below.


Aircraft proximity

Aircraft proximity. A situation in which, in the opinion of a
pilot or air traffic services personnel, the distance between
aircraft as well as their relative positions and speed have
been such that the safety of the aircraft involved may
have been compromised. An aircraft proximity is
classified as follows:


Risk of collision. The risk classification of an aircraft
proximity in which serious risk of collision has
existed.


Safety not assured. The risk classification of an aircraft
proximity in which the safety of the aircraft may have
been compromised.


No risk of collision. The risk classification of an aircraft
proximity in which no risk of collision has existed.


Risk not determined. The risk classification of an aircraft
proximity in which insufficient information was
available to determine the risk involved, or inconclusive
or conflicting evidence precluded such
determination.


Aircraft security check

Aircraft security check. An inspection of the interior of an aircraft to which passengers may have had access and an inspection
of the hold for the purposes of discovering suspicious objects, weapons, explosives or other dangerous devices, articles and
substances.


Aircraft security search. A thorough inspection of the interior and exterior of the aircraft for the purpose of discovering
suspicious objects, weapons, explosives or other dangerous devices, articles or substances.


Aircraft stand

Aircraft stand. A designated area on an apron intended to be used for parking an aircraft.


Aircraft station

Aircraft station (RR S1.83). A mobile station in the aeronautical
mobile service, other than a survival craft station,
located on board an aircraft.


Aircraft Variant

‘Aircraft Variant’ as used with respect to the licensing and operation of flight crew, means an aircraft of the same basic certificated type which contain modifications not resulting in significant changes of handling and/or flight characteristic, or flight crew complement, but causing significant changes to equipment and/or procedures.


Airframe

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


Airmanship

The consistent use of good judgement and well-developed knowledge, skills and attitudes to accomplish flight
objectives.


AIRMET

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


AIRPROX

AIRPROX. The code word used in an air traffic incident
report to designate aircraft proximity.


Airship

A power-driven lighter-than-air aircraft.


Airside

Airside. The movement area of an airport, adjacent terrain and buildings or portions thereof, access to which is controlled.


Airway

Airway. A control area or portion thereof established in the form of a corridor.


AIS product

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


ALERFA

ALERFA. The code word used to designate an alert phase.


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


Alert phase. A situation wherein apprehension exists as to the safety of an aircraft and its occupants.


Alerting post

Alerting post. Any facility intended to serve as an
intermediary between a person reporting an emergency and
a rescue coordination centre or rescue subcentre.


Alerting service

“alerting service” means a service provided by the appropriate ATS authority to notify
appropriate organisations regarding aircraft in need of search and rescue aid and to assist
such organisations as required.


ALSF-1

ALSF-1:   Approach Lighting System with Sequenced Flashing Lights configuration 1


ALSF-2

ALSF-2:   Approach Lighting System with Sequenced Flashing Lights configuration 2


Alternate aerodrome or heliport

“alternate aerodrome or heliport” means an aerodrome or heliport (including the
aerodrome or heliport of departure), which may be specified in a flight plan, to
which an aircraft in flight may proceed when it becomes impossible or inadvisable
to proceed to or to land at the aerodrome or heliport of intended landing; alternate
aerodromes include the following:


“take-off alternate” means an alternate aerodrome at which an aircraft can land
should this become necessary shortly after take-off and it is not possible to use the
aerodrome of departure;


“en-route alternate” means an aerodrome at which an aircraft would be able to land
after experiencing an abnormal or emergency condition while en route;


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


“destination alternate” means an alternate aerodrome to which an aircraft may
proceed should it become either impossible or inadvisable to la nd at the aerodrome
of intended landing;


Alternate airport

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


Altimetry system error

“altimetry system error (ASE)” means the difference between the altitude indicated
by the altimeter display assuming a correct altimeter barometric setting and the
pressure altitude corresponding to the undisturbed ambient pressure;


AMA

Area minimum altitude (AMA). The minimum altitude to be used under instrument meteorological conditions (IMC), that
provides a minimum obstacle clearance within a specified area, normally formed by parallels and meridians.


AMD

Ammended


Ampere

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


Angle of Incidence

The Angle of Incidence is the angle at which a wing is mounted onto a fuselage relative to the longitudinal axis.  It is also known as the Rigger's Angle.


ANSP

ANSP - Air Navigation Service Provider


Anti-collision light

“anti-collision light” means:
(a) in relation to rotorcraft, a flashing red light, and


(b) in relation to other aircraft, a flashing red or flashing white light and, in either case
showing in all directions for the purpose of enabling the aircraft to be more readily
detected by pilots of distant aircraft


Anticipated operating conditions

Anticipated operating conditions. Those conditions which are known from experience or which can be reasonably envisaged
to occur during the operational life of the aircraft taking into account the operations for which the aircraft is made
eligible, the conditions so considered being relative to the meteorological state of the atmosphere, to the configuration of
terrain, to the functioning of the aircraft, to the efficiency of personnel and to all the factors affecting safety in flight.
Anticipated operating conditions do not include:
a) those extremes which can be effectively avoided by means of operating procedures; and
b) those extremes which occur so infrequently that to require the Standards to be met in such extremes would give a
higher level of airworthiness than experience has shown to be necessary and practical.


APAPI

Abbreviated Precision Approach Path Indicator. A precision approach path indicator (PAPI) consisting of only two sharp cutoff light units situated on the left side of the runway.


API

Advance Passenger Information (API) System. An electronic communications system whereby required data elements are
collected and transmitted to border control agencies prior to flight departure or arrival and made available on the primary
line at the airport of entry.


Approach and landing operations using instrument approach procedures

“Approach and landing operations using instrument approach procedures” means
instrument approach and landing operations which are classified as follows:
“Non-precision approach and landing operations” - which means an
instrument approach which utilises lateral guidance but does not use vertical
guidance;


“Approach and landing operations with vertical guidance” - which means an
instrument approach and landing which utilises lateral and vertical guidance
but does not meet the requirements established for precision approach and
landing operations;


“Precision approach and landing operations” – which means an instrument
approach and landing using precision lateral and vertical guidance with
minima as determined by the category of operation;


Note: Lateral and vertical guidance refers to the guidance provided either by a
ground-based navigation aid or computer generated navigation data;


Approach Categories

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


Non-precision approach and landing operations.

An instrument approach and landing which utilizes lateral guidance but
does not utilize vertical guidance.


Approach and landing operations with vertical guidance. An instrument approach and landing which utilizes lateral and
vertical guidance but does not meet the requirements established for precision approach and landing operations.


Precision approach and landing operations. An instrument approach and landing using precision lateral and vertical
guidance with minima as determined by the category of operation.


Note.— Lateral and vertical guidance refers to the guidance provided either by:
a) a ground-based navigation aid; or
b) computer generated navigation data.


Categories of precision approach and landing operations:
Category I (CAT I) operation. A precision instrument approach and landing with:
a) a decision height not lower than 60 m (200 ft); and
b) with either a visibility not less than 800 m or a runway visual range not less than 550 m.


Category II (CAT II) operation. A precision instrument approach and landing with:
a) a decision height lower than 60 m (200 ft), but not lower than 30 m (100 ft); and
b) a runway visual range not less than 300 m.

Category IIIA (CAT IIIA) operation. A precision instrument approach and landing with:
a) a decision height lower than 30 m (100 ft) or no decision height; and
b) a runway visual range not less than 175 m.


Category IIIB (CAT IIIB) operation. A precision instrument approach and landing with:
a) a decision height lower than 15 m (50 ft), or no decision height; and
b) a runway visual range less than 175 m but not less than 50 m.


Category IIIC (CAT IIIC) operation. A precision instrument approach and landing with no decision height and no runway
visual range limitations.


Note.— Where decision height (DH) and runway visual range (RVR) fall into different categories of operation, the
instrument approach and landing operation would be conducted in accordance with the requirements of the most demanding
category (e.g. an operation with a DH in the range of CAT IIIA but with an RVR in the range of CAT IIIB would be considered
a CAT IIIB operation or an operation with a DH in the range of CAT II but with an RVR in the range of CAT I would be
considered a CAT II operation).


Approach control service

“approach control service” means air traffic control service for arriving or departing
controlled flights


Approach phase (Engines)

Approach phase. The operating phase defined by the time during which the engine is operated in the approach operating mode.

Take-off phase. The operating phase defined by the time during which the engine is operated at the rated thrust.


Appropriate ATS authority

“appropriate ATS authority” means in relation to the State, the Authority and, in relation to
any other state, the relevant authority designated by the state which has responsibility for
the provision of air traffic services in the airspace concerned, and in relation to those parts
of the high seas where, pursuant to a regional air navigation agreement, a state has
accepted responsibility for the provision of air traffic services, the relevant authority
designated by that state


Appropriate person

“appropriate person” means an authorised officer of the Authority as defined in the
Act or a person authorised by the appropriate Authority for the purposes of this
Order or the Chicago Convention.


Approval Dangerous Goods

Approval. An authorization granted by an appropriate national authority for:
a) the transport of dangerous goods forbidden on passenger and/or cargo aircraft where the Technical Instructions state
that such goods may be carried with an approval; or
b) other purposes as provided for in the Technical Instructions.


Note.— In the absence of a specific reference in the Technical Instructions allowing the granting of an approval, an
exemption may be sought.


Approved training

Training conducted under special curricula and supervision approved by a Contracting State.


Approved training organization

An organization approved by and operating under the supervision of a Contracting State in accordance with the requirements of Annex 1 to perform approved training.


Apron

“apron” means a defined area at a land aerodrome intended to accommodate aircraft for the
purposes of loading or unloading passengers, mail or cargo or for fuelling, parking or
maintenance


APV

APV – Approach Procedure with Vertical guidance. This term is used for RNP APCH operations that include vertical. guidance. That is, those flown to LNAV/VNAV or LPV minima.


Area control centre

“area control centre” (ACC) means a unit established by the appropriate ATS authority to provide
air traffic control service to controlled flights in control areas under its jurisdiction


Area control service

“area control service” means air traffic control service for controlled flights in control
areas;


Area navigation

“area navigation” means 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;


Area navigation route

“area navigation route” means an ATS route established by the appropriate ATS authority
for the use of aircraft capable of employing area navigation


Arrival routes

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


ASDA

Accelerate-stop distance available (ASDA). The length of the take-off run available plus the length of stopway, if provided.


ASHTAM

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


Associated aircraft systems

Associated aircraft systems. Those aircraft systems drawing electrical/pneumatic power from an auxiliary power unit during
ground operations.


ATA chapters

. A common industry referencing standard for aircraft technical documentation.
Note.— The competency frameworks of Chapter 4 use references to the ATA chapters numbering,
due to its widespread use in civil aviation.


ATC

“ATC” means the symbol used to designate air traffic control;


ATFM

Air traffic flow management (ATFM). A service established with the objective of contributing to a safe, orderly and
expeditious flow of air traffic by ensuring that ATC capacity is utilized to the maximum extent possible and that the
traffic volume is compatible with the capacities declared by the appropriate ATS authority.


ATIS

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


Data link-automatic terminal information service (D-ATIS). The provision of ATIS via data link.


Voice-automatic terminal information service (Voice-ATIS). The provision of ATIS by means of continuous and
repetitive voice broadcasts.


Atmosphere, International Standard

‘Atmosphere, International Standard’ means the atmosphere defined in ICAO Document 7488/2.
For the purposes of JAR the following is acceptable:-
a. The air is a perfect dry gas;
b The temperature at sea-level is 15°C;
c. The pressure at sea-level is 1.013250 x l05 Pa (29.92 in Hg) (1013.2 mbar);
d. The temperature gradient from sea-level to the altitude at which the temperature becomes -56.5°C is 3.25°C per 500 m (1.98°C/lOOOft );
e. The density at sea level ρσ, under the above conditions is 1.2250 kg/m3 (0.002378 slugs/ft3); for the density at altitudes up to 15 000 m (50 000 ft)

NOTE: ρ is the density appropriate to the altitude and p/ρσ the relative density is indicated by σ.


ATS

“ATS” means the symbol used to designate air traffic services;


ATS Route

“ATS route” means a route specified by the appropriate ATS authority designed for
channelling the flow of traffic as necessary for the provision of air traffic services
(including an airway, an advisory route, a controlled or uncontrolled route, an arrival route
or a departure route)


ATS surveillance service

A term used to indicate a 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.

Note.— A comparable ground-based system is one that has been demonstrated, by comparative assessment or other methodology, to have a level of safety and performance equal to or better than monopulse SSR.


Authorised officer

“authorised officer” means an authorised officer of the Authority as defined in
section 2 of the Act.


Authorized agent

Authorized agent. A person who represents an aircraft operator and who is authorized by or on behalf of such operator to act
on formalities connected with the entry and clearance of the operator’s aircraft, crew, passengers, cargo, mail, baggage or
stores and includes, where national law permits, a third party authorized to handle cargo on the aircraft.


Automatic Dependent Surveillance

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

Automatic dependent surveillance-broadcast (ADS-B) OUT. A function on an aircraft or vehicle that periodically broadcasts
its state vector (position and velocity) and other information derived from on-board systems in a format suitable for ADS-B
IN capable receivers

.
Automatic dependent surveillance-broadcast (ADS-B) IN. A function that receives surveillance data from ADS-B OUT data
sources.


Auxiliary Power Unit (APU)

‘Auxiliary Power Unit (APU)’ means any gas turbine-powered unit delivering rotating shaft
power, compressor air, or both which is not intended for direct propulsion of an aircraft.


Auxiliary rotor

‘Auxiliary rotor’ means a rotor that principally serves to counteract the effect of the main rotor torque on a rotorcraft and/or to manoeuvre the rotorcraft about one or more of its three principle axes


B

Background check

Background check. A check of a person’s identity and previous experience, including where legally permissible, any criminal
history, as part of the assessment of an individual’s suitability to implement a security control and/or for unescorted access
to a security restricted area.


Balloon

A non-power-driven lighter-than-air aircraft.
Note.— For the purposes of this Annex, this definition applies to free balloons.


Bare Earth

Bare Earth. Surface of the Earth including bodies of water and permanent ice and snow, and excluding vegetation and
man-made objects.


Barrette

Barrette. Three or more aeronautical ground lights closely spaced in a transverse line so that from a distance they appear as a
short bar of light.


Base Turn

“base turn” means 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 not being reciprocal


Becquerel

Becquerel (Bq). The activity of a radionuclide having one spontaneous nuclear transition per second.


BER

Bit error rate (BER). The number of bit errors in a sample divided by the total number of bits in the sample, generally
averaged over many such samples.


Beta Control

‘Beta Control’ means a system whereby the propeller can be operated at blade angles directly selected by the air crew, or by other means, and normally used during the approach and ground handling.


Blind transmission

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.


Boost Pressure

‘Boost Pressure’ (piston engines) means the manifold pressure measured relative to standard sea level atmospheric pressure.


Border integrity

Border integrity. The enforcement, by a State, of its laws and/or regulations concerning the movement of goods and/or
persons across its borders.


Brake Horsepower

‘Brake Horsepower’ means the power delivered at the propeller shaft (main drive or main output) of an aircraft engine.


BTPD

‘BTPD’ means body temperature, pressure, dry, i.e. 37°C, ambient pressure and no water vapour.


BTPS

‘BTPS’ means body temperature, pressure, saturated, i.e.37°C, ambient pressure and saturated with
water vapour at 47 mmHg partial pressure.


Bypass ratio

Bypass ratio. The ratio of the air mass flow through the bypass ducts of a gas turbine engine to the air mass flow through the
combustion chambers calculated at maximum thrust when the engine is stationary in an international standard atmosphere
at sea level.


C

Cabin crew member

“cabin crew member” (CCM) means a crew member who performs, in the interest of the
safety of passengers, duties assigned by the operator or the pilot-in-command of the
aircraft but who shall not act as a flight crew member.


CADM

C.A.D.M. - Central Data Acquisition Module


Calibrated airspeed

‘Calibrated airspeed’ (CAS) means indicated airspeed of an aircraft, corrected for position and instrument error. Calibrated airspeed is equal to true airspeed in standard atmosphere at sea level.


CALVERT I / ICAO-1 HIALS

CALVERT I / ICAO-1 HIALS:   ICAO-compliant configuration 1 High Intensity Approach Lighting System


CALVERT II / ICAO-2 HIALS

CALVERT II / ICAO-2 HIALS: ICAO-compliant configuration 2 High Intensity Approach Lighting System


Candela

Candela (cd). The luminous intensity, in the perpendicular direction, of a surface of 1/600 000 square metre of black body at
the temperature of freezing platinum under a pressure of 101 325 newtons per square metre.


Canopy

Canopy. Bare Earth supplemented by vegetation height.


Capacitor discharge light

Capacitor discharge light. A lamp in which high-intensity flashes of extremely short duration are produced by the discharge of
electricity at high voltage through a gas enclosed in a tube.


Cargo

“cargo” includes mail and animals.


Cargo aircraft

Cargo aircraft. Any aircraft, other than a passenger aircraft, which is carrying goods or property.


Carrier-to-multipath

Carrier-to-multipath ratio (C/M). The ratio of the carrier power received directly, i.e. without reflection, to the multipath
power, i.e. carrier power received via reflection.


Carrier-to-noise

Carrier-to-noise density ratio (C/No). The ratio of the total carrier power to the average noise power in a 1 Hz bandwidth,
usually expressed in dBHz.


Causes

Causes. Actions, omissions, events, conditions, or a combination thereof, which led to the accident or incident. The identification
of causes does not imply the assignment of fault or the determination of administrative, civil or criminal liability.


CDFA

Continuous descent final approach (CDFA) means a technique, consistent with stabilised approach procedures, for flying the final-approach segment of a non-precision instrument approach procedure as a continuous descent, without level-off, from an altitude/height at or above the final approach fix altitude/height to a point approximately 15 m (50 ft) above the landing runway threshold or the point where the flare manoeuvre shall begin for the type of aircraft flown.


Ceiling

“ceiling” means the height above the ground or water as the case may be of the base of the
lowest layer of cloud which is below 6,000 metres (20,000 feet) covering more than half
the sky;


Change-over point

“change-over point” means 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;


Channel rate

Channel rate. The rate at which bits are transmitted over the RF channel. These bits include those bits used for framing and
error correction, as well as the information bits. For burst transmission, the channel rate refers to the instantaneous burst
rate over the period of the burst.


Channel rate accuracy

Channel rate accuracy. This is relative accuracy of the clock to which the transmitted channel bits are synchronized. For
example, at a channel rate of 1.2 kbits/s, maximum error of one part in 106 implies the maximum allowed error in the clock is ±1.2 × 10-3 Hz.


Civil aviation inspector

Civil aviation inspector. A civil aviation inspector is an individual, designated by a Contracting State, who is charged with
the inspection of the safety, security or related aspects of air transport operations as directed by the appropriate authority.


Note.— Examples of civil aviation inspectors include inspectors responsible for airworthiness, flight operations and
other safety-related aspects, and security-related aspects, of air transport operations.


Class

As used with respect to aeroplanes means a group of single-pilot aeroplane types having similar handling and flight characteristics.


Clearance limit

“clearance limit” means the point to which an aircraft is granted an air traffic control
clearance


Clearance of goods

Clearance of goods. The accomplishment of the customs formalities necessary to allow goods to enter home use, to be
exported or to be placed under another customs procedure.


Clearway

‘Clearway’ means, for turbine engine powered aeroplanes certificated after August 29, 1959, an area beyond the runway, not less than 152 rn (500 ft) wide, centrally located ab.out the extended centreline of the runway, and under the control of the airport authorities. The clearway is expressed in terms of a clearway plane, extending from the end of the runway with an upward slope not exceeding 1.25%, above which no object or terrain protrudes. However, threshold lights may protrude above the plane if their height above the end of the runway is 0.66 m (26 ins) or less and if they are located to each side of the runway.


Cloud of operational significance

Cloud of operational significance. A cloud with the height of cloud base below 1 500 m (5 000 ft) or below the highest
minimum sector altitude, whichever is greater, or a cumulonimbus cloud or a towering cumulus cloud at any height.


Co-pilot

'Co-pilot' means a pilot serving in any piloting capacity other than as pilot-in-command or
commander, but excluding a pilot who is on board the aircraft for the sole purpose of receiving flight instruction for a licence or rating.


Collision avoidance logic

Collision avoidance logic. The sub-system or part of ACAS that analyses data relating to an intruder and own aircraft, decides
whether or not advisories are appropriate and, if so, generates the advisories. It includes the following functions: range and
altitude tracking, threat detection and RA generation. It excludes surveillance.


Commencement of journey

Commencement of journey. The point at which the person began his journey, without taking into account any airport at
which he stopped in direct transit, either on a through-flight or a connecting flight, if he did not leave the direct transit
area of the airport in question.


Commercial air transport operation

An aircraft operation involving the transport of passengers, cargo or mail for
remuneration or hire.


Commercial transport aircraft

“commercial transport aircraft” means an aircraft used or intended to be used by the
operator for the purpose of carrying passengers or cargo for which purpose payment
is required to be made or promised to the operator or, in a case where the carriage is
effected by an air transport undertaking, whether for payment or not;


Commissary supplies

Commissary supplies. Items, either disposable or intended for multiple use, that are used by the aircraft operator for
provision of services during flights, in particular for catering, and for the comfort of passengers.


Common Mark Registering

Common mark registering authority. The authority maintaining the non-national register or, where appropriate, the part
thereof, in which aircraft of an international operating agency are registered.


Competency

A combination of skills, knowledge and attitudes required to perform a task to the prescribed standard.


Competency element

An action that constitutes a task that has a triggering event and a terminating event that clearly defines its
limits, and an observable outcome.


Compressor air

‘Compressor air’ means compressed air that is provided by the APU to do work whether it is extracted or bled from any point of the compressor section of the gas turbine engine or produced from a compressor driven by the APU.


Configuration

Configuration (as applied to the aeroplane). A particular combination of the positions of the moveable elements, such as
wing flaps and landing gear, etc., that affect the aerodynamic characteristics of the aeroplane


Configuration deviation list

“configuration deviation list” (CDL) means a list established by the organisation
responsible for the type design, with the approval of the state of design, which
identifies any external parts of an aircraft type which may be missing at the
commencement of a flight and which contains, where necessary, any information on
associated operating limitations and performance correction.


Congested area

“congested area” means a densely populated area which is substantially used for
residential, commercial or recreational purposes and is without adequate safe
landing areas.


Consignment of dangerous goods

Consignment. One or more packages of dangerous goods accepted by an operator from one shipper at one time and at one
address, receipted for in one lot and moving to one consignee at one destination address.


Consultation

Consultation. Discussion with a meteorologist or another qualified person of existing and/or expected meteorological
conditions relating to flight operations; a discussion includes answers to questions


Contaminated Runway

A runway is considered to be contaminated when more than 25 % of the runway surface
area (whether in isolated areas or not) within the required length and width being used is covered by the
following:


(i) surface water more than 3 mm (0,125 in) deep, or by slush, or loose snow, equivalent to more than 3 mm
(0,125 in) of water;


(ii) snow which has been compressed into a solid mass which resists further compression and will hold together
or break into lumps if picked up (compacted snow); or


(iii) ice, including wet ice.


Continuing airworthiness

Continuing airworthiness. The set of processes by which an aircraft, engine, propeller or part complies with the applicable
airworthiness requirements and remains in a condition for safe operation throughout its operating life.


Contour line

Contour line. A line on a map or chart connecting points of equal elevation.


Control zone

“control zone” (CTR) means a controlled airspace extending upwards from the surface of the
earth to an upper limit specified by the appropriate ATS authority


Controlled aerodrome

Controlled aerodrome. An aerodrome at which air traffic control service is provided to aerodrome traffic.


Note.— The term “controlled aerodrome” indicates that air traffic control service is provided to aerodrome traffic but
does not necessarily imply that a control zone exists.


Controlled flight

“controlled flight” means any flight which is provided with air traffic control
services;


Controlled VFR flight

“controlled VFR flight” means a controlled flight conducted in accordance with the
visual flight rules


Corporate aviation

Corporate aviation. The non-commercial operation or use of aircraft by a company for the carriage of passengers or goods as
an aid to the conduct of company business, flown by a professional pilot employed to fly the aircraft. (Note that corporate
aviation is a subset of general aviation.)


COTS

C.O.T.S. - Commercial Off-The-Shelf


CPDLC

“controller-pilot data link communications” (CPDLC) means a means of communication
between controller and pilot using data link for ATC communications;


CRC

Cyclic redundancy check (CRC). A mathematical algorithm applied to the digital expression of data that provides a level of
assurance against loss or alteration of data.


Credit

Recognition of alternative means or prior qualifications.


Critical Altitude

‘Critical Altitude’ (piston engines) means the maximum attitude at which, in standard atmosphere, it is possible to maintain, at a specified rotational speed without ram, a specified power or a specified manifold pressure. Unless otherwise stated, the critical altitude is the maximum altitude at which it is possible to maintain, without ram, at the maximum continuous rotational speed, one of the following:-


a. The maximum continuous power, in the case of engines for which this power rating is the same at sea level and at the rated altitude.


b. The maximum continuous rated manifold pressure, in the case of engines the maximum continuous power of which, is governed by a constant manifold pressure.


Critical Engine

‘Critical Engine’ means the engine whose failure would most adversely affect the performance or handling qualities of an aircraft.


Critical Phases of Flight

Critical phases of flight in the case of aeroplanes means the take-off run, the take-off flight path, the final approach, the missed approach, the landing, including the landing roll, and any other phases of flight as determined by the pilot-in-command or commander;


Critical phases of flight in the case of helicopters means taxiing, hovering, take-off, final approach, missed approach, the landing and any other phases of flight as determined by the pilot-in-command or commander.


Cross-country

A flight between a point of departure and a point of arrival following a pre-planned route using standard
navigation procedures.


Cruise Climb

“cruise climb” means an aeroplane cruising technique resulting in a net increase in altitude
as the aeroplane mass decreases.


Cruise relief pilot

“cruise relief pilot” means a flight crew member who is assigned to perform pilot
tasks during cruise flight to allow the pilot-in-command or a co-pilot to obtain
planned rest.


Cruising level

“cruising level” means a level maintained during a significant portion of a flight;


Culture

Culture. All man-made features constructed on the surface of the Earth, such as cities, railways and canals.


Cumulonimbus

Recommendation.— An area of thunderstorms and cumulonimbus clouds should be considered:


a) obscured (OBSC) if it is obscured by haze or smoke or cannot be readily seen due to darkness;


b) embedded (EMBD) if it is embedded within cloud layers and cannot be readily recognized;


c) isolated (ISOL) if it consists of individual features which affect, or are forecast to affect, an area with a maximum
spatial coverage less than 50 per cent of the area concerned (at a fixed time or during the period of validity); and


d) occasional (OCNL) if it consists of well-separated features which affect, or are forecast to affect, an area with a
maximum spatial coverage between 50 and 75 per cent of the area concerned (at a fixed time or during the period of
validity).


current flight plan

“current flight plan” means the flight plan together with any changes caused by subsequent
clearances;


D

D-FIS

Data link flight information services (D-FIS). The provision of FIS via data link.


Damp Runway

A runway is considered damp when the surface is not dry, but when the moisture on it does not
give it a shiny appearance.


Danger Area

“danger area” means an airspace of dimensions specified by the appropriate ATS authority
within which activities dangerous to the flight of aircraft may exist at specified times;


Dangerous goods

“dangerous goods” means articles or substances which are capable of posing a risk
to health, safety, property or the environment and which are shown in the list of
dangerous goods in the Technical Instructions or which are classified according to
those Instructions, when transported by air;


Dangerous goods accident.

Dangerous goods accident. An occurrence associated with and related to the transport of dangerous goods by air which results
in fatal or serious injury to a person or major property or environmental damage.


Dangerous goods incident. An occurrence, other than a dangerous goods accident, associated with and related to the transport
of dangerous goods by air, not necessarily occurring on board an aircraft, which results in injury to a person, property or
environmental damage, fire, breakage, spillage, leakage of fluid or radiation or other evidence that the integrity of the
packaging has not been maintained. Any occurrence relating to the transport of dangerous goods which seriously
jeopardizes the aircraft or its occupants is also deemed to constitute a dangerous goods incident.


Datum

Datum. Any quantity or set of quantities that may serve as a reference or basis for the calculation of other quantities
(ISO 19104*).


DCPC

DCPC - Direct Controller/Pilot Communications


DDPG

Dispatch Deviation Procedures Guide (DDPG). Manual to identify any procedure to dispatch an aircraft
with allowable systems/components inoperative or missing.


De-icing/anti-icing facility

De-icing/anti-icing facility. A facility where frost, ice or snow is removed (de-icing) from the aeroplane to provide clean
surfaces, and/or where clean surfaces of the aeroplane receive protection (anti-icing) against the formation of frost or ice
and accumulation of snow or slush for a limited period of time.


Note.— Further guidance is given in the Manual of Aircraft Ground De-icing/Anti-icing Operations (Doc 9640).


De-icing/anti-icing pad. An area comprising an inner area for the parking of an aeroplane to receive de-icing/anti-icing
treatment and an outer area for the manoeuvring of two or more mobile de-icing/anti-icing equipment.


Decision Altitude

Decision altitude (DA) or decision height (DH). A specified altitude or height in the precision approach or approach with
vertical guidance at which a missed approach must be initiated if the required visual reference to continue the approach has
not been established.


Note 1.— Decision altitude (DA) is referenced to mean sea level and decision height (DH) is referenced to the threshold
elevation.


Note 2.— The required visual reference means that section of the visual aids or of the approach area which should have
been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position,
in relation to the desired flight path. In Category III operations with a decision height the required visual reference is that
specified for the particular procedure and operation.


Note 3.— For convenience where both expressions are used they may be written in the form “decision altitude/height” and
abbreviated “DA/H”.


Decision altitude (DA) or decision height (DH)

“decision altitude (DA) or decision height (DH)” means a specified altitude or
height in a precision approach or an approach with vertical guidance at which a
missed approach must be initiated if the required visual reference to continue the
approach has not been established; (Note: DA is referenced to mean sea level and
DH is referenced to the threshold elevation of the runway concerned);


Decision Height

‘Decision Height’, with respect to the operation of aircraft, means the wheel height above the runway elevation by which a go-around must be initiated unless adequate visual reference has been established and the aircraft position and approach path have been visually assessed as satisfactory to continue the approach and landing in safety.


Declarant

Declarant. Any person who makes a goods declaration or in whose name such a declaration is made.


Declared distances

Declared distances.
a) Take-off run available (TORA). The length of runway declared available and suitable for the ground run of
an aeroplane taking off.
b) Take-off distance available (TODA). The length of the take-off run available plus the length of the
clearway, if provided.
c) Accelerate-stop distance available (ASDA). The length of the take-off run available plus the length of the
stopway, if provided.
d) Landing distance available (LDA). The length of runway which is declared available and suitable for the
ground run of an aeroplane landing.


Defined point after take-off or before landing

“defined point after take-off or before landing” means, in the case of a multi-engine
helicopter, the point before which (during or after take-off) or after which (during
approach and landing) the helicopter’s ability to continue the flight safely, with one
engine inoperative, is not assured and a forced landing may be required;


DEM

Digital Elevation Model (DEM). The representation of terrain surface by continuous elevation values at all intersections of a
defined grid, referenced to common datum.


Note.— Digital Terrain Model (DTM) is sometimes referred to as DEM.


Density Altitude

Density altitude is the altitude relative to the standard atmosphere conditions (International Standard Atmosphere) at which the air density would be equal to the indicated air density at the place of observation, or, in other words, the height when measured in terms of the density of the air rather than the distance from the ground. "Density Altitude" is the pressure altitude adjusted for non-standard temperature.

Both an increase in temperature,  pressure, and, to a much lesser degree, humidity will cause an increase in density altitude. Thus, in hot and humid conditions, the density altitude at a particular location may be significantly higher than the true altitude.

In aviation the density altitude is used to assess the aircraft's aerodynamic performance under certain weather conditions. The lift generated by the aircraft's airfoils and the relation between indicated and true airspeed are also subject to air density changes. Furthermore, the power delivered by the aircraft's engine is affected by the air density and air composition.


Dependent parallel approaches

Dependent parallel approaches. Simultaneous approaches to parallel or near-parallel instrument runways where radar
separation minima between aircraft on adjacent extended runway centre lines are prescribed.


Deportation order

Deportation order. A written order, issued by the competent authorities of a State and served upon a deportee, directing him
to leave that State.


Deportee

Deportee. A person who had legally been admitted to a State by its authorities or who had entered a State illegally, and who
at some later time is formally ordered by the competent authorities to leave that State.


Derived version

Derived version of a helicopter. A helicopter which, from the point of view of airworthiness, is similar to the noise certificated
prototype but incorporates changes in type design which may affect its noise characteristics adversely.


Note 1.— In applying the Standards of this Annex, a helicopter that is based on an existing prototype but which is
considered by the certificating authority to be a new type design for airworthiness purposes shall nevertheless be considered as
a derived version if the noise source characteristics are judged by the certificating authority to be the same as the prototype.


Note 2.— “Adversely” refers to an increase of more than 0.30 EPNdB in any one of the noise certification levels for
helicopters certificated according to Chapter 8 and 0.30 dB(A) in the certification level for helicopters certificated according
to ICAO Annex 16 Chapter 11.


Derived version of an aeroplane. An aeroplane which, from the point of view of airworthiness, is similar to the noise
certificated prototype but incorporates changes in type design which may affect its noise characteristics adversely

.
Note 1.— Where the certificating authority finds that the proposed change in design, configuration, power or mass is so
extensive that a substantially new investigation of compliance with the applicable airworthiness regulations is required, the
aeroplane should be considered to be a new type design rather than a derived version

.
Note 2.— “Adversely” refers to an increase of more than 0.10 dB in any one of the noise certification levels unless the
cumulative effects of changes in type design are tracked by an approved procedure in which case “adversely” refers to a
cumulative increase in the noise level in any one of the noise certification levels of more than 0.30 dB or the margin of
compliance, whichever is smaller.


Design landing mass

Design landing mass. The maximum mass of the aircraft at which, for structural design purposes, it is assumed that it will be
planned to land.


Design take-off mass

Design take-off mass. The maximum mass at which the aircraft, for structural design purposes, is assumed to be planned to
be at the start of the take-off run.


Design taxiing mass

Design taxiing mass. The maximum mass of the aircraft at which structural provision is made for load liable to occur during
use of the aircraft on the ground prior to the start of take-off.


DETRESFA

DETRESFA. The code word used to designate a distress phase.


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.


Direct transit area

Direct transit area. A special area established in an international airport, approved by the public authorities concerned and
under their direct supervision or control, where passengers can stay during transit or transfer without applying for entry
to the State.


Direct transit arrangements

Direct transit arrangements. Special arrangements approved by the public authorities concerned by which traffic which is
pausing briefly in its passage through the Contracting State may remain under their direct control


Discrete source damage

Discrete source damage. Structural damage of the aeroplane that is likely to result from: impact with a bird, uncontained fan
blade failure, uncontained engine failure, uncontained high-energy rotating machinery failure or similar causes


Disembarkation

Disembarkation. The leaving of an aircraft after a landing, except by crew or passengers continuing on the next stage of the
same through-flight.


Disinfection

Disinfection. The procedure whereby health measures are taken to control or kill infectious agents on a human or animal
body, in or on affected parts of aircraft, baggage, cargo, goods or containers, as required, by direct exposure to chemical
or physical agents.


Disinsection

Disinsection. The procedure whereby health measures are taken to control or kill insects present in aircraft, baggage, cargo,
containers, goods and mail.


Dispatcher

Flight operations officer/flight dispatcher. A person designated by the operator to engage in the control and supervision of
flight operations, whether licensed or not, suitably qualified in accordance with Annex 1, who supports, briefs and/or
assists the pilot-in-command in the safe conduct of the flight.


Displaced threshold

Displaced threshold. A threshold not located at the extremity of a runway.


Disruptive passenger

Disruptive passenger. A passenger who fails to respect the rules of conduct at an airport or on board an aircraft or to follow the
instructions of the airport staff or crew members and thereby disturbs the good order and discipline at an airport or on board
the aircraft.


Ditching

Ditching. The forced landing of an aircraft on water.


Doppler shift

Doppler shift. The frequency shift observed at a receiver due to any relative motion between transmitter and receiver.


Double channel simplex

Double channel simplex. Simplex using two frequency
channels, one in each direction.


Note.— This method was sometimes referred to as crossband.


Downstream clearance

Downstream clearance. A clearance issued to an aircraft by an air traffic control unit that is not the current controlling
authority of that aircraft.


DPATO

DPATO - defined point after take-off (DPATO) means the point, within the take-off and initial climb phase, before which the helicopter’s ability to continue the flight safely, with the critical engine inoperative, is not assured and a forced landing may be required


DPBL

Defined point before landing (DPBL)’ means the point within the approach and landing phase, after which the helicopter’s ability to continue the flight safely, with the critical engine inoperative, is not assured and a forced landing may be required


Dry Runway

A dry runway is one which is neither wet nor contaminated, and includes those paved runways
which have been specially prepared with grooves or porous pavement and maintained to retain “effectively dry”
braking action even when moisture is present.


Dual instruction time

Flight time during which a person is receiving flight instruction from a properly authorized pilot on
board the aircraft.


Duplex

Duplex. A method in which telecommunication between two
stations can take place in both directions simultaneously.

Simplex. A method in which telecommunication between two
stations takes place in one direction at a time.


Dynamic load-bearing surface

Dynamic load-bearing surface. A surface capable of supporting the loads generated by a helicopter conducting an emergency
touchdown on it.


E

EAT

“expected approach time” means the time at which an air traffic control unit expects that
an arriving aircraft, following a delay, will leave the holding point to complete its approach
for a landing


EBOT

“estimated off blocks time” means the estimated time at which an aircraft will commence
movement associated with departure;


EDTO

EDTO critical fuel. The fuel quantity necessary to fly to an en-route alternate aerodrome considering, at the most critical point on the route, the most limiting system failure.

EDTO - Extended Diversion Time operations (ETOPS)


Note.— ICAO Annex 6 Attachment D contains guidance on EDTO critical fuel scenarios.


EDTO significant system

EDTO significant system. An aeroplane system whose failure or degradation could adversely affect the safety particular to an
EDTO flight, or whose continued functioning is specifically important to the safe flight and landing of an aeroplane during
an EDTO diversion.


EFB

E.F.B. - Electronic Flight Bag


Effective acceptance bandwidth

Effective acceptance bandwidth. The range of frequencies with respect to the assigned frequency for which reception is
assured when all receiver tolerances have been taken into account.


Effective adjacent channel rejection

Effective adjacent channel rejection. The rejection that is obtained at the appropriate adjacent channel frequency when all
relevant receiver tolerances have been taken into account.


Effective intensity

Effective intensity. The effective intensity of a flashing light is equal to the intensity of a fixed light of the same colour which
will produce the same visual range under identical conditions of observation.


Electronic aeronautical chart display

Electronic aeronautical chart display. An electronic device by which flight crews are enabled to execute, in a convenient and
timely manner, route planning, route monitoring and navigation by displaying required information.


Ellipsoid height

Ellipsoid height (Geodetic height). The height related to the reference ellipsoid, measured along the ellipsoidal outer normal
through the point in question.


ELT

Emergency locator transmitter (ELT). A generic term describing equipment which broadcast distinctive signals on designated
frequencies and, depending on application, may be automatically activated by impact or be manually activated. An ELT
may be any of the following:


Automatic fixed ELT (ELT(AF)). An automatically activated ELT which is permanently attached to an aircraft.


Automatic portable ELT (ELT(AP)). An automatically activated ELT which is rigidly attached to an aircraft but readily
removable from the aircraft.


Automatic deployable ELT (ELT(AD)). An ELT which is rigidly attached to an aircraft and which is automatically
deployed and activated by impact, and, in some cases, also by hydrostatic sensors. Manual deployment is also
provided.


Survival ELT (ELT(S)). An ELT which is removable from an aircraft, stowed so as to facilitate its ready use in an
emergency, and manually activated by survivors.


Embarkation

Embarkation. The boarding of an aircraft for the purpose of commencing a flight, except by such crew or passengers as have
embarked on a previous stage of the same through-flight.


Emergency phase

Emergency phase. A generic term meaning, as the case may be, uncertainty phase, alert phase or distress phase.


eMRTD

eMRTD. An MRTD (passport, visa or card) that has a contactless integrated circuit embedded in it and the capability of
being used for biometric identification of the MRTD holder in accordance with the standards specified in the relevant
Part of Doc 9303 — Machine Readable Travel Documents.


End-to-end

End-to-end. Pertaining or relating to an entire communication path, typically from (1) the interface between the information
source and the communication system at the transmitting end to (2) the interface between the communication system and
the information user or processor or application at the receiving end.


Equivalent airspeed

‘Equivalent airspeed’ (EAS) means the calibrated airspeed of an aircraft corrected for adiabatic
compressible flow for the particular altitude. Equivalent airspeed is equal to calibrated airspeed in standard atmosphere at sea level.


Equivalent isotropically

Equivalent isotropically radiated power (e.i.r.p.). The product of the power supplied to the antenna and the antenna gain in a
given direction relative to an isotropic antenna (absolute or isotropic gain).


Equivalent position

Equivalent position.

A position that can be established by means of a DME distance, a suitably located NDB or VOR, SRE or PAR fix or any other suitable fix between three and five miles from threshold that independently establishes the position of the aeroplane.


Error management

The process of detecting and responding to errors with countermeasures that reduce or eliminate the
consequences of errors and mitigate the probability of further errors or undesired states.

Note.— See Attachment C to Chapter 3 of the Procedures for Air Navigation Services — Training (PANS-TRG, Doc 9868)
and Circular 314 — Threat and Error Management (TEM) in Air Traffic Control for a description of undesired states.


Essential radio navigation service

Essential radio navigation service. A radio navigation service whose disruption has a significant impact on operations in the
affected airspace or aerodrome.


ETA

“estimated time of arrival” means 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.


EVS

Enhanced vision system (EVS). A system to display electronic real-time images of the external scene achieved through the use
of image sensors.


Exhaust Gas Temperature

‘Exhaust Gas Temperature’ (EGT) (turbine engines) means the average temperature of the exhaust gas stream obtained in an approved manner


Exhaust nozzle

Exhaust nozzle. In the exhaust emissions sampling of gas turbine engines where the jet effluxes are not mixed (as in some
turbofan engines for example) the nozzle considered is that for the gas generator (core) flow only. Where, however, the jet
efflux is mixed the nozzle considered is the total exit nozzle.


Extended Diversion Time

Extended diversion time operations (EDTO). Any operation by an aeroplane with two or more turbine engines where the
diversion time to an en-route alternate aerodrome is greater than the threshold time established by the State of the Operator.


Extended range operation

Extended range operation. Any flight by an aeroplane with two turbine engines where the flight time at the one engine
inoperative cruise speed (in ISA and still air conditions), from a point on the route to an adequate alternate aerodrome, is
greater than the threshold time approved by the State of the Operator.


External equipment

External equipment (helicopter). Any instrument, mechanism, part, apparatus, appurtenance, or accessory that is attached to or
extends from the helicopter exterior but is not used nor is intended to be used for operating or controlling a helicopter in
flight and is not part of an airframe or engine.


External load

‘External load’ means a load that is carried, towed or extends, outside the aircraft fuselage.]


F

Factor of safety

Factor of safety. A design factor used to provide for the possibility of loads greater than those assumed, and for uncertainties
in design and fabrication.


FAF

Final approach fix or point. That fix or point of an instrument approach procedure where the final approach segment
commences.


Fan marker beacon

Fan marker beacon. A type of radio beacon, the emissions of which radiate in a vertical fan-shaped pattern


FANS 1/A

FANS 1/A - Future Air Navigation System 1 or A. (Respectively, Boeing and Airbus Proprietary Air-Ground ATC Data Link Communications Systems)


Farad

Farad (F). The capacitance of a capacitor between the plates of which there appears a difference of potential of 1 volt when
it is charged by a quantity of electricity equal to 1 coulomb.


Fatigue

Fatigue. A physiological state of reduced mental or physical performance capability resulting from sleep loss or extended
wakefulness, circadian phase, or workload (mental and/or physical activity) that can impair a crew member’s alertness and
ability to safely operate an aircraft or perform safety-related duties.


FATO

Final approach and take-off area (FATO). A defined area over which the final phase of the approach manoeuvre to hover or
landing is completed and from which the take-off manoeuvre is commenced. Where the FATO is to be used by
performance Class 1 helicopters, the defined area includes the rejected take-off area available.


FBL

FBL - Used in meteorology meaning "light" as in precipitation or icing.


FDE

FDE - Fault Detection and Exclusion


Feathered Pitch

‘Feathered Pitch’ means the pitch setting, specified in the appropriate propeller manual, which in flight with the engine stopped, gives approximately the minimum drag, and corresponds with a windmilling torque of approximately zero.


FEC

Forward error correction (FEC). The process of adding redundant information to the transmitted signal in a manner which
allows correction, at the receiver, of errors incurred in the transmission.


Final Approach

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,


a) at the end of the last procedure turn, base turn or inbound turn of a racetrack procedure, if specified; or

b) 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:


1) a landing can be made; or
2) a missed approach procedure is initiated.


Final approach segment

Final approach segment. That segment of an instrument approach procedure in which alignment and descent for landing are
accomplished.


Final take-off speed

‘Final take-off speed’ means the speed of the aeroplane that exists at the end of the take-off path in the en-route configuration with one engine inoperative


FIR

“flight information region” means an airspace of defined dimensions designated by the
appropriate ATS authority within which flight information service and alerting service are
provided.


Fire-resistant

‘Fire-resistant.’ With respect to materials, components and equipment, means the capability to withstand the application of heat by a flame, as defined for ‘Fireproof‘, for a period of 5 minutes without any failure that would create a hazard to the aircraft.


NOTE: For materials this is considered to be equivalent to the capability of withstanding a fire at least as well as aluminium alloy in dimensions appropriate for the purposes for which they are used.


Fireproof

‘Fireproof.’ With respect to materials, components and equipment, means the capability to withstand the application of heat by a flame, for a period of 15 minutes without any failure that would create a hazard to the aircraft. The flame will have the following characteristics:-


Temperature 1100°C * 80°C
Heat Flux Density 116 KW/m2 10 KW/m2


NOTE: For materials this is considered to be equivalent to the capability of  withstanding a fire at least as well as steel or titanium in dimensions appropriate for the purposes for which they are used.


First aid oxygen

‘First aid oxygen’ means the additional oxygen provided for the use of passengers, who do not satisfactorily recover following subjection to excessive cabin altitudes, during which they had been provided with supplemental oxygen.


Fixed light

Fixed light. A light having constant luminous intensity when observed from a fixed point.


Flap extended speed

‘Flap extended speed’ means the highest speed permissible with wing-flaps in a prescribed extended position.


FLAS

FLAS - Flight Level Allocation Scheme


Flight crew member

A licensed crew member charged with duties essential to the operation of an aircraft during a flight duty
period.


Flight Level

“flight level” means a surface of constant atmospheric pressure which is related to a
specific pressure datum of 1013.2 hectopascals (hPa) and is separated from other such
surfaces by specific pressure intervals.


Flight plan

Specified information provided to air traffic services units, relative to an intended flight or portion of a flight of an
aircraft.


Flight procedures trainer

See Flight simulation training device.
Flight simulation training device. Any one of the following three types of apparatus in which flight conditions are simulated
on the ground:


A flight simulator, which provides an accurate representation of the flight deck of a particular aircraft type to the extent that
the mechanical, electrical, electronic, etc. aircraft systems control functions, the normal environment of flight crew
members, and the performance and flight characteristics of that type of aircraft are realistically simulated;


A flight procedures trainer, which provides a realistic flight deck environment, and which simulates instrument responses,
simple control functions of mechanical, electrical, electronic, etc. aircraft systems, and the performance and flight
characteristics of aircraft of a particular class;


A basic instrument flight trainer, which is equipped with appropriate instruments, and which simulates the flight deck
environment of an aircraft in flight in instrument flight conditions.
Flight simulator. See Flight simulation training device.


Flight recorder

“flight recorder” means any type of recorder installed in an aircraft for the purpose
of complementing accident/incident investigation and includes flight data and
cockpit voice recorders;


Flight safety documents system

“flight safety documents system” means a set of inter-related documentation
established by the operator, compiling and organising information necessary for
flight and ground operations and comprising, as a minimum, the operations manual
and the operator’s maintenance control manual;


Flight Status

“flight status” means an indication of whether or not a given aircraft requires special
handling by air traffic services units or not.


Flight time

Flight time — aeroplanes. The total time from the moment an aeroplane first moves for the purpose of taking off until the
moment it finally comes to rest at the end of the flight.
Note.— Flight time as here defined is synonymous with the term “block to block” time or “chock to chock” time in general
usage which is measured from the time an aeroplane first moves for the purpose of taking off until it finally stops at the end of
the flight.


Flight time — helicopters. The total time from the moment a helicopter’s rotor blades start turning until the moment the
helicopter finally comes to rest at the end of the flight, and the rotor blades are stopped.


Flight Visibility

“flight visibility” means the visibility forward from the cockpit of an aircraft in flight;


Foot

Foot (ft). The length equal to 0.304 8 metre exactly.


Frangible object

Frangible object. An object of low mass designed to break, distort or yield on impact so as to present the minimum hazard to
aircraft.


Free zone

Free zone. A part of the territory of a Contracting State where any goods introduced are generally regarded, insofar as import
duties and taxes are concerned, as being outside the customs territory.


Frequency channel

Frequency channel. A continuous portion of the frequency
spectrum appropriate for a transmission utilizing a specified
class of emission.
Note.— The classification of emissions and information
relevant to the portion of the frequency spectrum appropriate
for a given type of transmission (bandwidths) are specified in
the Radio Regulations, Article S2 and Appendix S1.


FRMS

Fatigue Risk Management System (FRMS). A data-driven means of continuously monitoring and managing fatigue-related
safety risks, based upon scientific principles and knowledge as well as operational experience that aims to ensure relevant
personnel are performing at adequate levels of alertness.


G

Gain-to-noise temperature ratio

Gain-to-noise temperature ratio. The ratio, usually expressed in dB/K, of the antenna gain to the noise at the receiver output
of the antenna subsystem. The noise is expressed as the temperature that a 1 ohm resistor must be raised to produce the
same noise power density.


GAMET

GAMET area forecast. An area forecast in abbreviated plain language for low-level flights for a flight information region or
sub-area thereof, prepared by the meteorological office designated by the meteorological authority concerned and
exchanged with meteorological offices in adjacent flight information regions, as agreed between the meteorological
authorities concerned.


GBAS

GBAS landing system (GLS) means an approach landing system using ground based augmented global navigation satellite system (GNSS/GBAS) information to provide guidance to the aircraft based on its lateral and vertical GNSS position. It uses geometric altitude reference for its final approach slope.


Geodesic distance

Geodesic distance. The shortest distance between any two points on a mathematically defined ellipsoidal surface.


Geodetic datum

Geodetic datum. A minimum set of parameters required to define location and orientation of the local reference system with
respect to the global reference system/frame.


Geoid

Geoid. The equipotential surface in the gravity field of the Earth which coincides with the undisturbed mean sea level (MSL)
extended continuously through the continents.
Note.— The geoid is irregular in shape because of local gravitational disturbances (wind tides, salinity, current, etc.) and
the direction of gravity is perpendicular to the geoid at every point.


Geoid undulation

Geoid undulation. The distance of the geoid above (positive) or below (negative) the mathematical reference ellipsoid.
Note.— In respect to the World Geodetic System — 1984 (WGS-84) defined ellipsoid, the difference between the WGS-84
ellipsoidal height and orthometric height represents WGS-84 geoid undulation.


Glide path.

Glide path. A descent profile determined for vertical guidance during a final approach.


Glider

A non-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.


Glider flight time

The total time occupied in flight, whether being towed or not, from the moment the glider first moves for the
purpose of taking off until the moment it comes to rest at the end of the flight.


GPT

G.P.T. - Ground Programming Tool


Gray

Gray (Gy). The energy imparted by ionizing radiation to a mass of matter corresponding to 1 joule per kilogram.


Gregorian calendar

Gregorian calendar. Calendar in general use; first introduced in 1582 to define a year that more closely approximates the
tropical year than the Julian calendar (ISO 19108*).
Note.— In the Gregorian calendar, common years have 365 days and leap years 366 days divided into twelve sequential
months.


Grid point data

Grid point data in digital form. Computer processed meteorological data for a set of regularly spaced points on a chart, for
transmission from a meteorological computer to another computer in a code form suitable for automated use.
Note.— In most cases, such data are transmitted on medium- or high-speed telecommunications channels.


Ground handling

“ground handling” means those services necessary for an aircraft’s arrival at and
departure from an airport, other than air traffic services;


Ground Idling Conditions

'Ground Idling Conditions’ (turbine engines) means the conditions of minimum rotational speed associated with zero forward speed and the maximum exhaust gas temperature at this speed.


Ground Visibility

“ground visibility” means the visibility at an aerodrome, as reported by an observer
accredited by the appropriate authority


Gyroplane

‘Gyroplane’ means a rotorcraft the rotors of which are not engine driven except for initial starting, but are made to rotate by action of the air when the rotorcraft is moving, and the means of propulsion of which, consisting usually of conventional propellers, is independent of the rotor system.


H

Hazard beacon

Hazard beacon. An aeronautical beacon used to designate a danger to air navigation.


Helicopter

A heavier-than-air aircraft supported in flight chiefly by the reactions of the air on one or more power-driven rotors
on substantially vertical axes.


Helicopter air taxiway

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


Helicopter clearway

Helicopter clearway. A defined area on the ground or water, selected and/or prepared as a suitable area over which a helicopter
operated in performance class 1 may accelerate and achieve a specific height.


Helicopter ground taxiway

Helicopter ground taxiway. A ground taxiway intended for the ground movement of wheeled undercarriage helicopters


Helideck

Helideck. A heliport located on an offshore structure such as an exploration or production platform used for the exploitation of
oil or gas.


HEMS

HEMS - Helicopter emergency medical services


Henry

Henry (H). The inductance of a closed circuit in which an electromotive force of 1 volt is produced when the electric current
in the circuit varies uniformly at a rate of 1 ampere per second.


Hertz

Hertz (Hz). The frequency of a periodic phenomenon of which the period is 1 second.


HHO

HHO - helicopter hoist operation


High energy rotor

‘High energy rotor’ means a rotating component or assembly which, when ruptured, will
generate high kinetic energy fragments.


Holding bay

Holding bay. A defined area where aircraft can be held, or bypassed, to facilitate efficient surface movement of aircraft.


Holding Point

“holding point” means:


(a) 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 air traffic control
clearances, or


(b) on the manoeuvring area of an aerodrome, a location at which an aircraft is held
before entering a runway


Holding procedure

Holding procedure. A predetermined manoeuvre which keeps an aircraft within a specified airspace while awaiting further
clearance.


Holdover time

Holdover time. The estimated time the anti-icing fluid (treatment) will prevent the formation of ice and frost and the
accumulation of snow on the protected (treated) surfaces of an aeroplane.


Homing

Homing. The procedure of using the direction-finding equipment
of one radio station with the emission of another
radio station, where at least one of the stations is mobile,
and whereby the mobile station proceeds continuously
towards the other station.


Hot spot

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.


HUD

Head-up display (HUD). A display system that presents flight information into the pilot’s forward external field of view.


Human performance

Human capabilities and limitations which have an impact on the safety and efficiency of aeronautical
operations.


Hypsometric tints

Hypsometric tints. A succession of shades or colour gradations used to depict ranges of elevation.


I

IAIP

Integrated Aeronautical Information Package. A package which consists of the following elements:
— AIP, including amendment service;
— Supplements to the AIP;
— NOTAM and PIB;
— AIC; and
— checklists and lists of valid NOTAM.


IAVW

International airways volcano watch (IAVW). International arrangements for monitoring and providing warnings to aircraft
of volcanic ash in the atmosphere.


Note.— The IAVW is based on the cooperation of aviation and non-aviation operational units using information derived
from observing sources and networks that are provided by States. The watch is coordinated by ICAO with the cooperation of
other concerned international organizations.


ICAO

‘ICAO’ means International Civil Aviation Organisation.


ICAO PKD

ICAO Public Key Directory (ICAO PKD). The central database serving as the repository of Document Signer Certificates
(CDS) (containing Document Signer Public Keys), CSCA Master List (MLCSCA), Country Signing CA Link Certificates
(lCCSCA) and Certificate Revocation Lists issued by Participants, together with a system for their distribution worldwide,
maintained by ICAO on behalf of Participants in order to facilitate the validation of data in eMRTDs.


Identification beacon

Identification beacon. An aeronautical beacon emitting a coded signal by means of which a particular point of reference can
be identified.


IFR conditions

‘IFR conditions’ means weather conditions below the minimum for flight under visual flight rules.


IGA

IGA - International General Aviation.


ILS

‘ILS’ means instrument landing system.


Immigration control

Immigration control. Measures adopted by States to control the entry into, transit through and departure from their territories
of persons travelling by air.


Import duties and taxes

Import duties and taxes. Customs duties and all other duties, taxes or charges, which are collected on or in connection with
the importation of goods. Not included are any charges which are limited in amount to the approximate cost of services
rendered or collected by the customs on behalf of another national authority.


Improperly documented person

Improperly documented person. A person who travels, or attempts to travel: (a) with an expired travel document or an
invalid visa; (b) with a counterfeit, forged or altered travel document or visa; (c) with someone else’s travel document or
visa; (d) without a travel document; or (e) without a visa, if required.


In-flight security officer

In-flight security officer. A person who is authorized by the government of the State of the Operator and the government of the
State of Registration to be deployed on an aircraft with the purpose of protecting that aircraft and its occupants against acts
of unlawful interference. This excludes persons employed to provide exclusive personal protection for one or more specific
people travelling on the aircraft, such as personal bodyguards.


Inadmissible person

Inadmissible person. A person who is or will be refused admission to a State by its authorities.


INCERFA

INCERFA. The code word used to designate an uncertainty phase.


Incident

Incident. An occurrence, other than an accident, associated with the operation of an aircraft which affects or could affect the
safety of operation.


Note.— The types of incidents which are of main interest to the International Civil Aviation Organization for accident
prevention studies are listed in Annex 13, Attachment C.


Incompatible Dangerous Goods

Incompatible. Describing dangerous goods which, if mixed, would be liable to cause a dangerous evolution of heat or gas or
produce a corrosive substance.


Independent paralle

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.


Independent parallel departures. Simultaneous departures from parallel or near-parallel instrument runways.


Indicated airspeed

“Indicated airspeed’ (IAS) means the speed of an aircraft as shown on its pitot static airspeed indicator calibrated to reflect standard atmosphere adiabatic compressible flow at sea level uncorrected for airspeed system errors.


Initial approach segment

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 procedure

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 flight time

Instrument flight time. Time during which a pilot is piloting an aircraft solely by reference to instruments and without external
reference points.


Instrument ground time

Time during which a pilot is practising, on the ground, simulated instrument flight in a flight
simulation training device approved by the Licensing Authority.


Instrument Runway

Instrument runway. One of the following types of runways intended for the operation of aircraft using instrument approach
procedures:


a) 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.


b) Precision approach runway, category I. An instrument runway served by ILS and/or MLS and visual aids
intended for operations with a decision height not lower than 60 m (200 ft) and either a visibility not less
than 800 m or a runway visual range not less than 550 m.


c) Precision approach runway, category II. An instrument runway served by ILS and/or MLS and visual aids
intended for operations with a decision height lower than 60 m (200 ft) but not lower than 30 m (100 ft)
and a runway visual range not less than 350 m.


d) Precision approach runway, category III. An instrument runway served by ILS and/or MLS to and along
the surface of the runway and:


A C intended for operations with a decision height lower than 30 m (100 ft), or no decision height and
a runway visual range not less than 200 m.


B C intended for operations with a decision height lower than 15 m (50 ft), or no decision height and a
runway visual range less than 200 m but not less than 50 m

.
C C intended for operations with no decision height and no runway visual range limitations

.
Note.C Visual aids need not necessarily be matched to the scale of non-visual aids provided. The criterion for the
selection of visual aids is the conditions in which operations are intended to be conducted.


Instrument time

Instrument flight time or instrument ground time.


Intermediate approach segment

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 a reversal, racetrack or dead reckoning track procedure and the
final approach fix or point, as appropriate.


Intermediate holding position

Intermediate holding position. A designated position intended for traffic control at which taxiing aircraft and vehicles shall
stop and hold until further cleared to proceed, when so instructed by the aerodrome control tower.


International airport

International airport. Any airport designated by the Contracting State in whose territory it is situated as an airport of entry
and departure for international air traffic, where the formalities incident to customs, immigration, public health, animal
and plant quarantine and similar procedures are carried out.


Interpilot air-to-air

Interpilot air-to-air communication. Two-way communication
on the designated air-to-air channel to enable aircraft
engaged in flights over remote and oceanic areas out of
range of VHF ground stations to exchange necessary operational
information and to facilitate the resolution of
operational problems.


Investigation

Investigation. A process conducted for the purpose of accident prevention which includes the gathering and analysis of
information, the drawing of conclusions, including the determination of causes and/or contributing factors and, when
appropriate, the making of safety recommendations.


Investigator-in-charge

Investigator-in-charge. A person charged, on the basis of his or her qualifications, with the responsibility for the organization,
conduct and control of an investigation.
Note.— Nothing in the above definition is intended to preclude the functions of an investigator-in-charge being assigned to
a commission or other body.


Isogonal

Isogonal. A line on a map or chart on which all points have the same magnetic variation for a specified epoch.


Isogriv

Isogriv. A line on a map or chart which joins points of equal angular difference between the North of the navigation grid and
Magnetic North.


Isolated aerodrome

(a) Isolated aerodrome. A destination aerodrome for which there is no destination alternate aerodrome suitable for a given
aeroplane type.

(b) Isolated aerodrome. If acceptable to the Authority, the destination aerodrome can be considered as an isolated aerodrome,


if the fuel required (diversion plus final) to the nearest adequate destination alternate aerodrome is more than:
For aeroplanes with reciprocating engines, fuel to fly for 45 minutes plus 15 % of the flight time planned to be spent
at cruising level or two hours, whichever is less; or


For aeroplanes with turbine engines, fuel to fly for two hours at normal cruise consumption above the destination aerodrome, including final reserve fuel.


J

Joule

Joule (J). The work done when the point of application of a force of 1 newton is displaced a distance of 1 metre in the
direction of the force.


JRCC

Joint rescue coordination centre (JRCC). A rescue
coordination centre responsible for both aeronautical and
maritime search and rescue operations.


K

Kelvin

Kelvin (K). A unit of thermodynamic temperature which is the fraction 1/273.16 of the thermodynamic temperature of the
triple point of water


Kilogram

Kilogram (kg). The unit of mass equal to the mass of the international prototype of the kilogram.


Knot

Knot (kt). The speed equal to 1 nautical mile per hour.


Known consignor

Known consignor. A consignor who originates cargo or mail for its own account and whose procedures meet common security
rules and standards sufficient to allow the carriage of cargo or mail on any aircraft.


L

Lading

Lading. The placing of cargo, mail, baggage or stores on board an aircraft to be carried on a flight.

Unlading. The removal of cargo, mail, baggage or stores from an aircraft after a landing.


Landing Area

“landing area” means that part of the movement area intended for the landing or take-off of
aircraft


Landing direction indicator

Landing direction indicator. A device to indicate visually the direction currently designated for landing and for take-off.


Landing gear extended speed

“Landing gear extended speed’ means the maximum speed at which an aircraft can be safely flown with the landing gear extended.


Landing gear operating speed

‘Landing gear operating speed’ means the maximum speed at which the landing gear can be safely extended or retracted.


Large aeroplane

‘Large aeroplane’ means an aeroplane of more than 5700 kg (12,500 pounds) maximum certificated take-off weight. The category ‘Large Aeroplane’ does not include the commuter aeroplane category.


LCFZ

Laser-beam critical flight zone (LCFZ). Airspace in the proximity of an aerodrome but beyond the LFFZ where the irradiance
is restricted to a level unlikely to cause glare effects.


Laser-beam free flight zone (LFFZ). Airspace in the immediate proximity of the aerodrome where the irradiance is restricted
to a level unlikely to cause any visual disruption.


Laser-beam sensitive flight zone (LSFZ). Airspace outside, and not necessarily contiguous with, the LFFZ and LCFZ where
the irradiance is restricted to a level unlikely to cause flash-blindness or after-image effects.


LDA

Landing distance available (LDA). The length of runway which is declared available and suitable for the ground run of an
aeroplane landing.


LDIN

LDIN:   Lead-in lighting


LDP

Landing decision point (LDP) means the point used in determining landing performance from which, an engine failure having been recognised at this point, the landing may be safely continued or a balked landing initiated.


Lighting system reliability

Lighting system reliability. The probability that the complete installation operates within the specified tolerances and that the
system is operationally usable.


Likely

In the context of the medical provisions in Chapter 6, likely means with a probability of occurring that is unacceptable to
the medical assessor.


Limit loads

Limit loads. The maximum loads assumed to occur in the anticipated operating conditions.


Litre

Litre (L). A unit of volume restricted to the measurement of liquids and gases which is equal to 1 cubic decimetre.


Load factor

‘Load factor’ means the ratio of a specified load to the total weight of the aircraft. The specified load is expressed in terms of any of the following: aerodynamic forces, inertia forces, or ground or water reactions


Location indicator

Location indicator. A four-letter code group formulated in
accordance with rules prescribed by ICAO and assigned to
the location of an aeronautical fixed station.


Lumen

Lumen (lm). The luminous flux emitted in a solid angle of 1 steradian by a point source having a uniform intensity
of 1 candela.


Lux

Lux (lx). The illuminance produced by a luminous flux of 1 lumen uniformly distributed over a surface of 1 square metre.


LVP

Low visibility procedures (LVP) means procedures applied at an aerodrome for the purpose of ensuring safe operations during lower than standard category I, other than standard category II, category II and III approaches and low visibility take-offs


LVTO

Low visibility take-off (LVTO) means a take-off with an RVR lower than 400 m but not less than 75 m.


M

Mach number

‘Mach number’ means the ratio of true air speed to the speed of sound.


Magnetic variation

Magnetic variation. The angular difference between True North and Magnetic North.
Note.— The value given indicates whether the angular difference is East or West of True North.


Main rotor

‘Main rotor(s)’ means the rotor or rotors that supply the principal lift to a rotorcraft


MALSF

MALSF - Medium-intensity Approach Lighting System with Sequenced Flashing lights


MALSR

MALSR - Medium-intensity Approach Lighting System with Runway Alignment Indicator Lights


Manifold Pressure

‘Manifold Pressure’ piston engines means the absolute static pressure measured at the appropriate point in the induction system, usually in inches or millimetres of mercury.


Manoeuvring area

“manoeuvring area” means that part of an aerodrome used for the take-off, landing and
taxiing of aircraft, excluding aprons


MAPt

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.

Author's Note : Turns are not normally made during a go-around before the MAPt


Marker

Marker. An object displayed above ground level in order to indicate an obstacle or delineate a boundary.


Marking. A symbol or group of symbols displayed on the surface of the movement area in order to convey aeronautical
information.


Master Minimum Equipment list (MMEL)

“Master Minimum Equipment list (MMEL)” means a list established for a particular
aircraft type by the organisation responsible for the type design with the approval of
the State of Design containing items, one or more of which is permitted to be
unserviceable at the commencement of a flight and which may be associated with
special operating conditions limitations or procedures for that flight;


Maximum Best Economy Cruising Power Conditions

‘Maximum Best Economy Cruising Power Conditions’ means the crankshaft rotational
speed, engine manifold pressure and any other parameters recommended in the engine
manuals as appropriate for use with economical-cruising mixture strength.


Maximum Contingency Powe

Turbine Engines:-
Power / thrust definitions applicable to engines for aeroplanes and helicopters:-

NOTES: (1) The performance data are provided be the engine constructor and give the power and/or thrust
produced by an engine under specified conditions (e.g. intake efficiency, forward speed,
atmospheric temperature) when operating within the limitations (e.g. rpm, exhaust gas
temperature) which have been approved for use with the defined power/thrust condition.


(2) Definitions of power/thrust in terms of usage and duration (and the use of these to form the basis
of certain Flight Manual limitations) is not intended to remove the pilot’s right to judge whether and
to what extent such limitations may be ignored in emergency conditions.

a) ‘Maximum Contingency Power and/or Thrust’ means the power and/or thrust identified in
the performance data for use when a power-unit has failed or been shut down during take-off, baulked
landing or prior to a discontinued approach and limited in use for a continuous period of not more than
2½ minutes.
NOTE: The 2½ minute period for use of maximum contingency power and/or thrust is additional to the 5 minute
or 10 minute period at take-off power and/or thrust (see c.) and may be added to the take-off limitation at any
point in time.

b) ‘Maximum Contingency Power and/or Thrust Rating’ means the minimum test bed
acceptance power and/or thrust, as stated in the engine type certificate data sheet, of series and
newly overhauled engines when running at the specified conditions and within the appropriate
acceptance limitations.

c) ‘Take-off Power and/or Thrust’ means the power and/or thrust identified in the performance
data for use during take-off, discontinued approach and baulked landing; and
i. for aeroplanes and helicopters, limited in use to a continuous period of not more than 5
minutes; and
ii. for aeroplanes only (when specifically requested), limited in use to’a continuous period of
not more than 10 minutes in the event of a power-unit having failed or been shut down.

d) ‘Take-off Power and/or Thrust Rating’ means the minimum test bed acceptance power and/or
thrust as stated in the engine type certificate data sheet, of series and newly overhauled engines
when running at the specified conditions and within the appropriate acceptance limitations.

e) ‘Intermediate Contingency Power and/or Thrust’ means the power and/or thrust identified in
the performance data for use after take-off when a power-unit has failed or been shut down,
during periods of unrestricted duration.

f) ‘Intermediate Contingency Power and/or Thrust Rating’ means the minimum test bed
acceptance power and/or thrust, as stated in the engine type certificate data sheet, of series and
newly overhauled engines when running at the specified conditions and within the appropriate
acceptance limitations.

g) ‘30-Minute Contingency Power’ (applicable to multi-engined helicopters only) means the power
identified in the performance data for use after take-off when an engine has failed or been shut
down, and limited in scheduled use for a total period of not more than 30 minutes in any one flight.

h) ‘30-Minute Contingency Power Rating’ (applicable to multi-engined helicopters only) means
the minimum test bed acceptance power, as stated in the engine type certificate data sheet, of
series and overhauled engines when running at the specified conditions and within the
appropriate acceptance limitations.

j) ’Maximum Continuous Power and/or Thrust’ means the power and/or thrust identified in the
performance data for use during periods of unrestricted duration.
NOTE: It should not be assumed that the maximum permitted continuous power and/or thrust is appropriate
to normal operations. The power to be used in such conditions can only be arrived at by discussion
between the constructors and operators, due regard being paid to the effect of such factors as the type of
operation envisaged, the route and climatic conditions, together with the overhaul period and overhaul
costs which it is desired to achieve.

k) ‘Maximum Continuous Power and/or Thrust Rating’ means the minimum test bed acceptance
power and/or thrust, as stated in the engine type certificate data sheet, of series and newly
overhauled engines when running at the specified conditions and within the appropriate
acceptance limitations.

 


Maximum Continuous Power

Power definitions applicable to engines for aeroplanes and helicopters

'Maximum Continuous Power’ means the output shaft power identified in the performance data
for use during periods of unrestricted duration.


Maximum diversion time

Maximum diversion time. Maximum allowable range, expressed in time, from a point on a route to an en-route alternate
aerodrome.


Maximum Engine Overspeed

‘Maximum Engine Overspeed’ (20 second-piston engines) means the maximum engine rotational speed, inadvertent occurrence of which for periods of up to 20 seconds, has been agreed not to require rejection of the engine from service or maintenance action (other than to correct the cause).


Maximum Engine Overspeed(s)

‘Maximum Engine Overspeed(s)’ (20 second-turbine engines) means the maximum rotational speed of each mechanically independent main rotating system of an engine, inadvertent occurrence of which for periods of up to 20 seconds, has been agreed not to require rejection of the engine from service or maintenance action (other than to correct the cause). NOTE: For each main rotating system this speed is normally not less than the maximum transient rpm in non-fault conditions.


Maximum Governed Rotational Speed

‘Maximum Governed Rotational Speed’ (variable pitch (governing) propellers) means the maximum
rotational speed as determined by the setting of the propeller governor or control mechanism.


Maximum mass

“maximum mass” means the maximum certificated mass of an aircraft (Maximum certificated take-off mass.)


Maximum Permissible Rotational Speed

‘Maximum Permissible Rotational Speed’ (fixed, adjustable or variable (non-governing) pitch
propellers) means the maximum propeller rotational speed permitted in normal or likely emergency
operation.


Maximum Power-turbine Overspeed

‘Maximum Power-turbine Overspeed’ (20 second-applicable only to free power-turbine engines for
helicopters) means the maximum rotational speed of the free power-turbine, inadvertent occurrence
of which for periods of up to 20 seconds, has been agreed not to require rejection of the engine from
service or maintenance action (other than to correct the cause).


Maximum Power-turbine Speed for Autorotation

‘Maximum Power-turbine Speed for Autorotation’ (applicable only to free power-turbine engines
for helicopters) means the maximum rotational speed of the power-turbine permitted during
autorotation for periods of unrestricted duration.


Maximum Propeller Overspeed

‘Maximum Propeller Overspeed’ (20 second) means the maximum propeller rotational speed,
inadvertent occurrence of which for periods of up to 20 seconds, has been agreed not to require
rejection of the propeller from service or maintenance action (other than to correct the cause).


Maximum Recommended Cruising Power Conditions

‘Maximum Recommended Cruising Power Conditions’ means the crankshaft rotational
speed, engine manifold pressure and any other parameters recommended in the engine
manuals as appropriate for cruising operation.


Maximum total mass authorised

“maximum total mass authorised” (MTMA) means the maximum total mass of the aircraft and its contents at which the aircraft may take off in accordance with the certificate of airworthiness in force in respect of the aircraft and the associated flight manual limitations and regulated performance.


MEA

Minimum en-route altitude (MEA). The altitude for an en-route segment that provides adequate reception of relevant
navigation facilities and ATS communications, complies with the airspace structure and provides the required obstacle
clearance.


Mean power (of a radio transmitter)

Mean power (of a radio transmitter). The average power supplied to the antenna transmission line by a transmitter during an interval of time sufficiently long compared with the lowest frequency encountered in the modulation taken under normal operating conditions.


Met Abbreviations

A = Altimeter Setting
Ac = Altocumulus cloud
AcCast = Altocumulus Castellenas cloud
AcLent = Altocumulus Lenticularis cloud
ACSL = Altocumulus Standing Lenticular cloud
AGL = Above Ground Level
Aireps = Aircraft Reports
ANAPROP = Anomalous Propagation
As = Altostratus cloud
ASDAR = Aircraft to Satellite Data Relay
ASL = Above Sea Level
atm = Standard Atmosphere (101325 Pa)
AUTO = Automatic (Weather Station)
AVN = A type of NWP model
AWS = Automatic Weather Station

B

BC = Patches (usually used with FG)
BECMG = Becoming
Bf = Beaufort force
BKN = Broken cloud (5/8, 6/8 or 7/8 cover)
BL = Blowing
BR = Mist

C

cP = Polar Continental Airmass (Pc also used)
cT = Tropical Continental Airmass (Tc also used)
C = Centigrade
CA = Cloud to air ligtning (usually used in conjunction with the LTG abbreviation)
CAT = Clear Air Turbulence Cb = Cumulonimubus cloud
CbMam = Cumulonimbus Mamatus cloud
Cc = Cirrocumulus cloud
CC = Cloud to cloud ligtning (usually used in conjunction with the LTG abbreviation)
CCSL = Cirrocumulus Standing Lenticular cloud
CG = Cloud to ground ligtning (usually used in conjunction with the LTG abbreviation)
CH = High level clouds (or Ch)
Ci = Cirrus cloud
CIG = Cloud ceiling height
CL = Low level clouds (or Cl)
CLD = Cloud
CLR = Sky Clear
CM = Medium level clouds (or Cm)
CONS = Constant
COR = Corrected Report
Cs = Cirrostratus cloud
Cu = Cumulus cloud
CuCon = Cumulus Congestus cloud (sometimes called Towering Cumulus and given abbrev. Cu2)
CuHu = Cumulus Humilis cloud
CuMed = Cumulus Medicoris cloud

D

DALR = Dry Adiabatic Lapse Rate
DR = Drifting
DS = Duststorm
DSNT = Distant
DU = Dust in suspension in the air
DZ = Drizzle

E

ECMWF = European Centre for Medium Range Weather Forecasts
ELR = Environmental Lapse Rate
EMBD = Embedded
ENSO = El Nino/a Southern Oscillation
ERS = Earth Resources Satellite
EUMETSAT = European Meteorological Satellite

F

F = Fahrenheit
Fc = Fractocumulus cloud
FC = Funnel cloud (includes Tornado & Waterspout)
FEW = Few clouds (1/8 or 2/8 cover)
FG = Fog
FLOP = Floating Point Operation
FM = From
FPS = Feet per second
FROPA = Frontal passage
FRQ = Frequent
Fs = Fractostratus cloud
FU = Smoke
FZ = Freezing

G

g = Acceleraion due to gravity
GARP = Global Atmospheric Research Programme
GCM = Global Computer Model
GF = Ground Frost
GMT = Grenwich Mean Time
GOES = Geostationary Satellite
GR = Hail
GS = Small Hail or Soft Hail
GTS = Global Telecommunications System

H

H = High
HI = Heat Index
hPa = Hectopascals
HZ = Haze

I

IC = Ice Crystals
IC = In cloud ligtning (usually used in conjunction with the LTG abbreviation)
ICAO = International Civil Aviation Organization
IMO = International Meteorological Organization (now WMO)
INSAT = Indian Satellite
IR = Infra-Red
ITCZ = Inter-Tropical Convergance Zone

J

K

K = Kelvin
KT = Knots

L

L = Low
LAM = Limited Area model
Loran = Long Range Navigation
LTG = Lightning

M

mA = Arctic Maritime Airmass (Am also used)
mb = millibars
mbar = millibars
mP = Polar Maritime Airmass (Pm also used)
mT = Tropical Maritime Airmass (Tm also used)
M = Less than (when used with visibility) or minus (when used with temperatures)
METAR = Meteorological Actual Report
METEOSAT = Meteorological Satellite
MI = Shallow (usually used with FG)
MO = Met Office (usually UKMO)
MOS = Model Output Statistics
MOV(G) = Moving
MPS = Metres per second
MRF = Medium Range Forecast
MSL = Mean Seal Level
MSLP = Mean Sea Level Pressure
MTW = Mountain Waves

N

NLC = Noctilucent Cloud
NOAA = National Oceanic and Atmospheric Administration
NOGAPS = National Oceanographic Global Atmospheric Prediction System
Ns = Nimbostratus cloud
NWP = Numerical Weather Predication (A computer model)
NWS = National Weather Service (USA)

O

OCNL = Occasional
O(V)HD = Overhead
OMNTS = Over Mountains
OVC = Overcast cloud (8/8 cover)

P

P = More than
Pa = Pascal(s)
PE = Ice Pellets
PK = Peak
PO = Dust Devils
PPI = Plan Position Indicator (a type of rainfall radar system)
PR = Partial (usually used with FG)
PRESSFR = Pressure Falling Rapidly
PRESSRR = Pressure Rising Rapidly
PROB = Probability
PY = Spray

Q

QBO = Quasi-biennial Oscillation

R

rmP = Returning Polar Maritime Airmass (or rPm)
RE = Recent
RH = Relative Humidity
RHI = Range Height Indicator (a type of rainfall radar system)
RMK = Remarks

S

SA = Sand in suspension in the air
SALR = Saturated Adiabatic Laspe Rate
Sc = Stratocumulus
SCSL = Stratocumulus Standing Lenticular cloud
SCT = Scattered cloud (3/8 or 4/8 cover)
SF = Sferic (radio interference caused by lightning strikes)
SFC = Surface
SFLOC = Sferic Location
SG = Snowgrains
SIGMET = Significant Met. (used in aviation reports)
SKC = Sky Clear
SM = Statute Mile(s)
SN = Snow
SNINCR = Snow Increasing Rapidly
SPECI = Special (METAR) Report
SQ = Squall
SS = Sandstorm
SST = Sea Surface Temperature
St = Stratus cloud
STWS = Storm Tide Warning Service
SYNOP = Synoptic Report

T

TAF = Terminal Aerodrome Forecast (used in aviation reports)
TCU = Towering Cumulus cloud
Td = Dewpoint Temperature
TEMPO = Temporarily
THI = Temperature-Humidity index
TIL = Until
TS = Thunderstorm
Tt = Air Temperature

U

UHIE = Urban Heat Island Effect
UKMO = UK Met Office
UP = Unknown Precipitation
UTC = Universal Time Co-ordinate (GMT)
UV = Ultra-Violet

V

V = Varying
VA = Volcanic Ash
VC = (in the) vicinity
VIS = Visible (when associated with satellite images) or Visibility (when associated with surface obs.)
VOLMET = Flying (vol is French for fly) Met. (a voice weather broadcast for pilots)
VRB = Variable
VV = Vertical Visibility

W

WMO = World Meteorological Office
WSHFT = Wind shift
WV = Water vapour (reffering to satellite images)
WWW = World Weather Watch
Wx = Weather

X

Y

Z

Z = Zulu (Grenwich Mean Time)

Symbols

+ = Heavy
- = Light
/ = Not measured
$ = weather station maintainence due


Metadata

Metadata. Data about data (ISO 19115*).


Metre

Metre (m). The distance travelled by light in a vacuum during 1/299 792 458 of a second.


Metric Tonne

Tonne (t). The mass equal to 1 000 kilograms.


Microlight

‘Microlight’ is an aeroplane having no more than two seats, Vs,, not exceeding 35 knots (65 KM/h) CAS, and
a maximum take-off mass of no more than:-
 - 300 kg for a landplane, single seater; or
 - 330 kg for an amphibian or floatplane, single seater; or
 - 495 kg for an amphibian or floatplane, two-seater, provided that a microlight capable of operating as both a floatplane and a landplane falls below both MTOM limits, as appropriate.
- 450 kg for a landplane, two-seater; or
Note: Foot-launched aircraft are excluded from this definition.


MIL Spec

‘MIL Spec’ means USA Military Specification


Minimum descent altitude/height (MDA/MDH)

Minimum descent altitude (MDA) or minimum descent height (MDH). A specified altitude or height in a non-precision
approach or circling approach below which descent must not be made without the required visual reference.


Note 1.— Minimum descent altitude (MDA) is referenced to mean sea level and minimum descent height (MDH) is
referenced to the aerodrome elevation or to the threshold elevation if that is more than 2 m (7 ft) below the aerodrome elevation.
A minimum descent height for a circling approach is referenced to the aerodrome elevation.


Note 2.— The required visual reference means that section of the visual aids or of the approach area which should have
been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position,
in relation to the desired flight path. In the case of a circling approach the required visual reference is the runway environment.


Note 3.— For convenience when both expressions are used they may be written in the form “minimum descent altitude/
height” and abbreviated “MDA/H”.


Minimum Equipment List (MEL)

“Minimum Equipment List (MEL)” means a list which provides for the operation of
an aircraft, subject to specified conditions, with particular equipment inoperative,
prepared by the aircraft operator in conformity with or more restrictive than the
Master Minimum Equipment List (MMEL);


Minimum sector altitude

Minimum sector altitude. The lowest altitude which may be used which will provide a minimum clearance of 300 m (1 000 ft)
above all objects located in an area contained within a sector of a circle of 46 km (25 NM) radius centred on a radio aid to
navigation


Mishandled baggage

Mishandled baggage. Baggage involuntarily, or inadvertently, separated from passengers or crew.


Missed approach procedure

Missed approach procedure. The procedure to be followed if the approach cannot be continued.


Mobile surface station

Mobile surface station. A station in the aeronautical telecommunication
service, other than an aircraft station,
intended to be used while in motion or during halts at
unspecified points.


MOCA

Minimum obstacle clearance altitude (MOCA). The minimum altitude for a defined segment of flight that provides the
required obstacle clearance.


Mode S subnetwork

Mode S subnetwork. A means of performing an interchange of digital data through the use of secondary surveillance radar
(SSR) Mode S interrogators and transponders in accordance with defined protocols.


Modified Engine

‘Modified Engine’ means an engine, previously approved, in which hitherto unapproved
modifications have been embodied.


Mole

Mole (mol). The amount of substance of a system which contains as many elementary entities as there are atoms in
0.012 kilogram of carbon-12.


Note.— When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons,
other particles or specified groups of such particles


MOPSC

Maximum operational passenger seating configuration (MOPSC) means the maximum passenger seating capacity of an individual aircraft, excluding crew seats, established for operational purposes and specified in the operations manual. Taking as a baseline the maximum passenger seating configuration established during the certification process conducted for the type certificate (TC), supplemental type certificate (STC) or change to the TC or STC as relevant to the individual aircraft, the MOPSC may establish an equal or lower number of seats, depending on the operational constraints


MORA (M.O.R.A.)

 

MORAs – minimum off route altitudes. There are two types of MORAs – one is called a route MORA and the other is the grid MORA. Because of the imprecise navigation provided by NDBs and the ADFs used in the aeroplanes, the early route MORAs provided an obstacle clearance within 10 nautical miles on both sides of the airways and within a 10-nautical mile radius around the ends of the airways. The 10-nautical mile criterion is with us today. To create the route MORAs today, the enroute chart compilers at Jeppesen analyze the visual aeronautical charts for each respective location around the world to determine the ground elevations below the airways to produce the route MORA for each airway segment.


Movement area

“movement area” means that part of an aerodrome used for the take-off, landing and
taxiing of aircraft, consisting of the manoeuvring area and the apron(s).


MTW

Recommendation.— A mountain wave (MTW) should be considered:


a) severe whenever an accompanying downdraft of 3.0 m/s (600 ft/min) or more and/or severe turbulence is observed
or forecast; and


b) moderate whenever an accompanying downdraft of 1.75–3.0 m/s (350–600 ft/min) and/or moderate turbulence is
observed or forecast.


N

Navigation specification

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:
Required navigation performance (RNP) specification. A navigation specification based on area navigation that includes
the requirement for performance monitoring and alerting, designated by the prefix RNP, e.g. RNP 4, RNP APCH.
Area navigation (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, e.g. RNAV 5, RNAV 1.


Note.— The Performance-based Navigation (PBN) Manual (Doc 9613), Volume II, contains detailed guidance on
navigation specifications.


NCD

NCD - No cloud detected


NDV

NDV - No directional variation (meteorology)


Near-parallel runways

Near-parallel runways. Non-intersecting runways whose extended centre lines have an angle of convergence/divergence of 15
degrees or less.


Newton

Newton (N). The force which when applied to a body having a mass of 1 kilogram gives it an acceleration of 1 metre per
second squared.


Night

The hours between the end of evening civil twilight and the beginning of morning civil twilight or such other period.


between sunset and sunrise, as may be prescribed by the appropriate authority.
Note.— Civil twilight ends in the evening when the centre of the sun’s disc is 6 degrees below the horizon and begins in the
morning when the centre of the sun’s disc is 6 degrees below the horizon.


Night-Ireland

“night” means the hours between the end of evening civil twilight and the beginning of
morning civil twilight, or such other period between sunset and sunrise as may be specified
by the appropriate authority. In or over the State, “night” shall be deemed to be, during the
period beginning on the 1st day of April, and ending on the 30th day of September, the
time between half an hour after sunset and half an hour before sunrise, and during the
remainder of the year, the time between sunset and sunrise, and for the purpose of this
definition sunset shall be determined at surface level.


NM

Nautical mile (NM). The length equal to 1 852 metres exactly.


Non-instrument runway

Non-instrument runway. A runway intended for the operation of aircraft using visual approach procedures.


Normal operating differential pressure

‘Normal operating differential pressure’ means the pressure differential between the cabin
pressure and the outside ambient pressure, including the tolerances of the normal pressure regulating
system.


NOSIG

The trend forecast shall indicate significant changes in respect of one or more of the elements: surface wind, visibility,
weather and clouds. Only those elements shall be included for which a significant change is expected. However, in the case
of significant changes in respect of cloud, all cloud groups, including layers or masses not expected to change, shall be
indicated. In the case of a significant change in visibility, the phenomenon causing the reduction of visibility shall also be
indicated. When no change is expected to occur, this shall be indicated by the term “NOSIG”.

NOTE : Refer to ICAO Annex 3, 2.2 - 2.2.7


NOTAM

NOTAM. 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.

SNOWTAM. A special series NOTAM notifying the
presence or removal of hazardous conditions due to
snow, ice, slush or standing water associated with snow,
slush and ice on the movement area, by means of a
specific format.


NPA

'NPA’ means Notice of Proposed Amendment.


NSS

N.S.S. - Network Server System


NTPD

'NTPD’ means normal temperature, pressure, dry, i.e. 2l°C, 760 mmHg and no water vapour.


NVIS

Aided night vision imaging system (NVIS) flight means, in the case of NVIS operations, that portion of a visual flight rules (VFR) flight performed at night when a crew member is using night vision goggles (NVG);


O

Obstacle

Obstacle. All fixed (whether temporary or permanent) and mobile objects, or parts thereof, that:
a) are located on an area intended for the surface movement of aircraft; or
b) extend above a defined surface intended to protect aircraft in flight; or
c) stand outside those defined surfaces and that have been assessed as being a hazard to air navigation.


Note.— The term obstacle is used in this Annex solely for the purpose of specifying the charting of objects that are considered
a potential hazard to the safe passage of aircraft in the type of operation for which the individual chart series is
designed.


Obstacle clearance altitude

“obstacle clearance altitude (OCA) or obstacle clearance height (OCH)” means the
lowest altitude or lowest height above the elevation of the relevant runway threshold
or the aerodrome elevation as applicable, used in establishing compliance with
appropriate obstacle clearance criteria;


Obstacle clearance limit (OCL)

“obstacle clearance limit (OCL)” means the height above the elevation of an
aerodrome below which the minimum required vertical clearance cannot be
maintained on approach or in the event of a missed approach;


OCA

Obstacle clearance altitude (OCA) or obstacle clearance height (OCH). The lowest altitude or the lowest height above the
elevation of the relevant runway threshold or the aerodrome elevation as applicable, used in establishing compliance with
appropriate obstacle clearance criteria.


Note 1.— Obstacle clearance altitude is referenced to mean sea level and obstacle clearance height is referenced to the
threshold elevation or in the case of non-precision approaches to the aerodrome elevation or the threshold elevation if that is
more than 2 m (7 ft) below the aerodrome elevation. An obstacle clearance height for a circling approach is referenced to the
aerodrome elevation.


Note 2.— For convenience when both expressions are used they may be written in the form “obstacle clearance
altitude/height” and abbreviated “OCA/H”.


Note 3.— See Procedures for Air Navigation Services — Aircraft Operations (Doc 8168), Volume I, Part I, Section 4,
Chapter 1, 1.5, and Volume II, Part I, Section 4, Chapter 5, 5.4, for specific applications of this definition.

 


ODALS

ODALS:   Omni directional Approach Lighting System


OEI

‘OEI’ means one engine inoperative


Offset frequency simplex

Offset frequency simplex. A variation of single channel
simplex wherein telecommunication between two stations
is effected by using in each direction frequencies that are intentionally slightly different but contained within a
portion of the spectrum allotted for the operation.


OFZ

Obstacle free zone (OFZ). The airspace above the inner approach surface, inner transitional surfaces, and balked landing
surface and that portion of the strip bounded by these surfaces, which is not penetrated by any fixed obstacle other than a
low-mass and frangibly mounted one required for air navigation purposes.


Ohm

Ohm (Ω). The electric resistance between two points of a conductor when a constant difference of potential of 1 volt, applied
between these two points, produces in this conductor a current of 1 ampere, this conductor not being the source of any
electromotive force.


OIS

OIS - Onboard Information Systems


Operational control

“operational control” means the exercise of authority over the initiation,
continuation, diversion or termination of a flight in the interest of the safety of the
aircraft, those on board and the regularity and efficiency of that


Operational control communications

Operational control communications. Communications
required for the exercise of authority over the initiation,
continuation, diversion or termination of a flight in the
interest of the safety of the aircraft and the regularity and
efficiency of a flight.
Note.— Such communications are normally required for the
exchange of messages between aircraft and aircraft operating
agencies.


Operational flight plan

“operational flight plan” means the operator’s plan for the safe conduct of the flight
based on considerations of aircraft performance, other operating limitations and
relevant expected conditions on the route to be followed and at the aerodromes
concerned


Operator

“operator” means a person, organisation or enterprise engaged in or offering to
engage in an aircraft operation; and who or which, in relation to any particular
aircraft, has at the relevant time the responsibility for the management of that
aircraft; the operator of a commercial transport aircraft is the holder of an air
operator certificate from the state of the operator concerned; the operator of a private
or an aerial work aircraft is the registered owner;


Ornithopter

Ornithopter. A heavier-than-air aircraft supported in flight chiefly by the reactions of the air on planes to which a flapping
motion is imparted.


Orthometric height

Orthometric height. Height of a point related to the geoid, generally presented as an MSL elevation.


Overpack

Overpack. An enclosure used by a single shipper to contain one or more packages and to form one handling unit for
convenience of handling and stowage.


Note.— A unit load device is not included in this definition.


Package. The complete product of the packing operation consisting of the packaging and its contents prepared for transport.


Packaging. Receptacles and any other components or materials necessary for the receptacle to perform its containment
function.


Note.— For radioactive material, see ICAO Annes 18 Part 2, paragraph 7.2 of the Technical Instructions.


Oxides of nitrogen

Oxides of nitrogen. The sum of the amounts of the nitric oxide and nitrogen dioxide contained in a gas sample calculated as if
the nitric oxide were in the form of nitrogen dioxide.


P

PAPI

1. An approach path indicator system consisting of four sharp cutoff light units situated on the left side of the runway (on both sides of the runway, in the case of the military) in the form of a wing bar.

 

2. An airport lighting facility, similar to VASI, providing vertical approach slope guidance to aircraft during approach to landing.


PAR

Precision approach radar (PAR). Primary radar equipment
used to determine the position of an aircraft during final
approach, in terms of lateral and vertical deviations
relative to a nominal approach path, and in range relative
to touchdown.
Note.— Precision a

pproach radars are designated to
enable pilots of aircraft to be given guidance by
radiocommunication during the final stages of the
approach to land.


Pascal

Pascal (Pa). The pressure or stress of 1 newton per square metre.


Passenger amenities

Passenger amenities. Facilities provided for passengers which are not essential for passenger processing.


Performance Class 1

“Performance Class 1” means, in relation to a helicopter, performance such that, in
the case of critical power unit failure, it is able to land on the rejected take-off area
or safely continue the flight to an appropriate landing area, depending on when the
failure occurs


Performance Class 2

“Performance Class 2” means, in relation to a helicopter, performance such that in
the case of critical power unit failure, it is able to safely continue the flight, except
when the failure occurs prior to a defined point after take-off or after a defined point
before landing, in which case a forced landing may be required;


Performance Class 3

“Performance Class 3” means, in relation to a helicopter, performance such that, in
the case of power unit failure at any point in the flight profile, a forced landing must
be performed;


Performance criteria

Simple, evaluative statements on the required outcome of the competency element and a description of
the criteria used to judge whether the required level of performance has been achieved.


Person with disabilities

Person with disabilities. Any person whose mobility is reduced due to a physical incapacity (sensory or locomotor), an
intellectual deficiency, age, illness or any other cause of disability when using transport and whose situation needs
special attention and the adaptation to the person’s needs of the services made available to all passengers.


PF/PNF

'PF' means Pilot flying.
'PNF' means Pilot not flying.


PIB

PIB

Preflight Information Bulletin


Pilot in command

‘Pilot in command’ means the pilot responsible for the operation and safety of an aircraft during
flight time.


PNR

Point of no return. The last possible geographic point at which an aeroplane can proceed to the destination aerodrome as well
as to an available en-route alternate aerodrome for a given flight.


Point light

Point light. A luminous signal appearing without perceptible length.


Portrayal

Portrayal. Presentation of information to humans (ISO 19117*).


Position

Position (geographical). Set of coordinates (latitude and longitude) referenced to the mathematical reference ellipsoid which
define the position of a point on the surface of the Earth.


Powered sailplane

‘Powered sailplane’ means an aircraft, equipped with one or more engines having, with engine(s)
inoperative, the characteristics of a sailplane.


Powered-lift

Powered-lift. A heavier-than-air aircraft capable of vertical take-off, vertical landing, and low-speed flight, which depends
principally on engine-driven lift devices or engine thrust for the lift during these flight regimes and on non-rotating
aerofoil(s) for lift during horizontal flight


Powerplant

Powerplant. The system consisting of all the engines, drive system components (if applicable), and propellers (if installed),
their accessories, ancillary parts, and fuel and oil systems installed on an aircraft but excluding the rotors for a helicopter.


Precision Approach

Precision approach procedure. An instrument approach procedure utilizing azimuth and glide path information provided by
ILS or PAR.


Preliminary Report

Preliminary Report. The communication used for the prompt dissemination of data obtained during the early stages of the
investigation.


Pressure altitude

“pressure altitude” means an atmospheric pressure expressed in terms of altitude
which corresponds to that pressure in the Standard Atmosphere as defined in Annex
8 to the Chicago Convention


Prevailing visibility

Prevailing visibility. The greatest visibility value, observed in accordance with the definition of “visibility”, which is reached
within at least half the horizon circle or within at least half of the surface of the aerodrome. These areas could comprise
contiguous or non-contiguous sectors.


Note.— This value may be assessed by human observation and/or instrumented systems. When instruments are installed,
they are used to obtain the best estimate of the prevailing visibility.


Primary frequency

Primary frequency. The radiotelephony frequency assigned to
an aircraft as a first choice for air-ground communication
in a radiotelephony network.


Secondary frequency. The radiotelephony frequency assigned
to an aircraft as a second choice for air-ground communication
in a radiotelephony network


Primary radar

Primary radar. A radar system which uses reflected radio
signals.


Primary surveillance radar (PSR). A surveillance radar
system which uses reflected radio signals


Private aircraft

“private aircraft” means an aircraft which is neither a commercial transport aircraft
nor an aerial work aircraft


PRM

PRMs - Persons with reduced mobility


Problematic use of substances

“problematic use of substances” means the use of one or more psychoactive substances by
aviation personnel in a way that constitutes a direct hazard to the user or endangers the
lives, health or welfare of others or causes or worsens an occupational, social mental or
physical problem or disorder


Procedure altitude/height

Procedure altitude/height. A specified altitude/height flown operationally at or above the minimum altitude/height and
established to accommodate a stabilized descent at a prescribed descent gradient/angle in the intermediate/final approach
segment.


Procedure turn.

Procedure turn. A manoeuvre in which a turn is made away from a designated track followed by a turn in the opposite direction
to permit the aircraft to intercept and proceed along the reciprocal of the designated track.


Note 1.— Procedure turns are designated “left” or “right” according to the direction of the initial turn.
Note 2.— Procedure turns may be designated as being made either in level flight or while descending, according to the
circumstances of each individual procedure.


Proficiency check

“proficiency check” means a demonstration of skill to revalidate or renew a flight
crew licence rating and including such oral examination as the examiner may
require


Profile

Profile. The orthogonal projection of a flight path or portion
thereof on the vertical surface containing the nominal
track.


Prognostic chart

Prognostic chart. A forecast of a specified meteorological element(s) for a specified time or period and a specified surface or
portion of airspace, depicted graphically on a chart.


Prohibited area

“prohibited area” means airspace of defined dimensions designated by the appropriate
authority above the land areas of the country or territorial waters thereof, within which the
flight of aircraft is prohibited by such authority;


Protected flight zones

Protected flight zones. Airspace specifically designated to mitigate the hazardous effects of laser radiation.


Protected service volume

Protected service volume. A part of the facility coverage where the facility provides a particular service in accordance with
relevant SARPs and within which the facility is afforded frequency protection.


Protection area

Protection area. An area within a taxi-route and around a helicopter stand which provides separation from objects, the FATO,
other taxi-routes and helicopter stands, for safe manoeuvring of helicopters.


PSR blip

PSR blip. The visual indication, in non-symbolic form, on a
radar display of the position of an aircraft obtained by
primary radar.


Psychoactive substances

“psychoactive substances” means alcohol, opoids, cannabinoids, sedatives and
hypnotics, cocaine, other psychostimulants, hallucinogens and volatile solvents,
whereas coffee and tobacco are excluded


Public authorities

Public authorities. The agencies or officials of a Contracting State responsible for the application and enforcement of the
particular laws and regulations of that State which relate to any aspect of these Standards and Recommended Practices


Public health emergency

Public health emergency of international concern. An extraordinary event which is determined, as provided in the
International Health Regulations (2005) of the World Health Organization: (i) to constitute a public health risk to other
States through the international spread of disease and (ii) to potentially require a coordinated international response.


Public health risk

Public health risk. A likelihood of an event that may affect adversely the health of human populations, with an emphasis on
one which may spread internationally or may present a serious and direct danger.


Q

Quality assurance

Quality assurance. Part of quality management focused on providing confidence that quality requirements will be fulfilled
(ISO 9000*).


R

Radar approach

Radar approach. An approach in which the final approach
phase is executed under the direction of a radar controller.


Radar clutter

Radar clutter. The visual indication on a radar display of
unwanted signals.


Radar contact

Radar contact. The situation which exists when the radar
position of a particular aircraft is seen and identified on a
radar display.


Radar identification

Radar identification. The situation which exists when the
radar position of a particular aircraft is seen on a radar
display and positively identified by the air traffic
controller.


Radar monitoring

Radar monitoring. The use of radar 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.


Radar separation

Radar separation. The separation used when aircraft position
information is derived from radar sources.


Radar track position

Radar track position. An extrapolation of aircraft position by
the computer based upon radar information and used by
the computer for tracking purposes.


Note.— In some cases, information other than radarderived
information is used to assist the tracking
processes.


Radian

Radian (rad). The plane angle between two radii of a circle which cut off on the circumference an arc equal in length to the
radius.


Radio navigation service

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.


RAIL

RAIL:   Runway Alignment Indicator Lights


RAIM

Receiver autonomous integrity monitoring

 

1) A technique whereby a civil GNSS receiver / processor determines the integrity of the GNSS navigation signals without reference to senders or non-DoD integrity systems other than the receiver itself. This determination is achieved by consistency check among redundant pseudorange measurements.

 

2) A form of ABAS whereby a GNSS receiver processor determines the integrity of the GNSS navigation signals using only GPS signals or GPS signals augmented with altitude (baroaiding). This determination is achieved by a consistency check among redundant pseudo-range measurements.

 


Rated thrust

Rated thrust. For engine emissions purposes, the maximum take-off thrust approved by the certificating authority for use under
normal operating conditions at ISA sea level static conditions, and without the use of water injection. Thrust is expressed in
kilonewtons.


RCP

Required communication performance (RCP). A statement of the performance requirements for operational communication
in support of specific ATM functions


Readback

Readback. A procedure whereby the receiving station repeats
a received message or an appropriate part thereof back to
the transmitting station so as to obtain confirmation of
correct reception.


Reference landing speed

‘Reference landing speed’ (Vref) means the speed of the aeroplane, in a specified landing configuration,
at the point where it descends through the landing screen height in the determination of the landing
distance for manual landings.


Reference pressure ratio

Reference pressure ratio. The ratio of the mean total pressure at the last compressor discharge plane of the compressor to the
mean total pressure at the compressor entry plane when the engine is developing take-off thrust rating in ISA sea level
static conditions.


Note.— Methods of measuring reference pressure ratio are given in ICAO Annes 16 Appendix 1.


Regular station

Regular station. A station selected from those forming an enroute
air-ground radiotelephony network to communicate
with or to intercept communications from aircraft in
normal conditions.


Regulated agent

Regulated agent. An agent, freight forwarder or any other entity who conducts business with an operator and provides security
controls that are accepted or required by the appropriate authority in respect of cargo or mail.


REIL

REIL:   Runway End Identification Lights


Rejected take-off (RTO) area

Rejected take-off (RTO) area. A defined area on a heliport suitable for helicopters operating in performance class 1 to complete a
rejected take-off.


Release of goods

Release of goods. The action by the customs authorities to permit goods undergoing clearance to be placed at the disposal of
the persons concerned.


Relief

Relief. The inequalities in elevation of the surface of the Earth represented on aeronautical charts by contours, hypsometric tints,
shading or spot elevations.


Relief flights

Relief flights. Flights operated for humanitarian purposes which carry relief personnel and relief supplies such as food,
clothing, shelter, medical and other items during or after an emergency and/or disaster and/or are used to evacuate
persons from a place where their life or health is threatened by such emergency and/or disaster to a safe haven in the
same State or another State willing to receive such persons.


Removal of a person

Removal of a person. Action by the public authorities of a State, in accordance with its laws, to direct a person to leave that
State.

Removal order. A written order served by a State on the operator on whose flight an inadmissible person travelled into that
State, directing the operator to remove that person from its territory.


Repair

“repair” means the restoration of an aeronautical product to an airworthy condition
to ensure that the aircraft continues to comply with the design aspects of the
appropriate airworthiness requirements for the issuance of the type certificate for the
respective aircraft type, after it has been damaged or subjected to wear;


Repetitive flight plan

“repetitive flight plan” means a flight plan related to a series of frequently recurring,
regularly operated individual flights with identical basic features, submitted by an operator
for retention and repetitive use by air traffic services units


Reporting point

Reporting point. A specified (named) geographical location in relation to which the position of an aircraft can be reported.


Note.— There are three categories of reporting points: ground-based navigation aid, intersection and waypoint. In the
context of this definition, intersection is a significant point expressed as radials, bearings and/or distances from ground-based
navigation aids. A reporting point can be indicated as “on request” or as “compulsory”.


Required navigation performance

“required navigation performance” (RNP) means a statement of the navigation
performance accuracy necessary for operation within a defined airspace with a
containment value (termed RNP Type) 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


RESA

Runway end safety area (RESA). An area symmetrical about the extended runway centre line and adjacent to the end of the
strip primarily intended to reduce the risk of damage to an aeroplane undershooting or overrunning the runway.


Rescue

Rescue. An operation to retrieve persons in distress, provide
for their initial medical or other needs, and deliver them to
a place of safety.


Rescue coordination centre

Rescue coordination centre (RCC). A unit responsible for promoting efficient organization of search and rescue services and for
coordinating the conduct of search and rescue operations within a search and rescue region.

Rescue subcentre (RSC). A unit subordinate to a rescue
coordination centre, established to complement the latter
according to particular provisions of the responsible
authorities.


Resolution

Resolution. A number of units or digits to which a measured or calculated value is expressed and used.


Rest period

“rest period” means any period of time on the ground during which a flight crew
member is relieved of all duties by the operator


Restricted area

“restricted area” means an airspace of defined dimensions designated by the appropriate
authority above the land areas of a country or the territorial waters thereof, within which
the flight of aircraft is restricted by the appropriate authority in accordance with certain
specified conditions;


Reversal procedure

Reversal procedure. A procedure designed to enable aircraft to reverse direction during the initial approach segment of an
instrument approach procedure. The sequence may include procedure turns or base turns.


Rigger's Angle

Rigger's Angle is another name for the Angle of Incidence.


Risk assessment

Risk assessment. An assessment by a deporting State of a deportee’s suitability for escorted or unescorted removal via
commercial air services. The assessment should take into account all pertinent factors, including medical, mental and
physical fitness for carriage on a commercial flight, willingness or unwillingness to travel, behavioural patterns and any
history of violence.


Risk management

Risk management. The systematic application of management procedures and practices which provide border inspection
agencies with the necessary information to address movements or consignments which represent a risk.


RMZ

RMZ - Radio Mandatory Zone


Rotational Speed

‘Rotational Speed’ (engine) means, unless otherwise qualified (e.g. propeller rotational speed), the
rotational speed in revolutions per minute of the engine crankshaft or its equivalent.


‘Rotational Speed’ (propeller) means, unless otherwise specified (e.g. propeller rpm), the speed in
revolutions per minute of the engine crankshaft or its equivalent.


Rotorcraft

‘Rotorcraft’ means a heavier-than-air aircraft that depends principally for its support in flight on the
lift generated by one or more rotors.


Rotorcraft-load combination

'Rotorcraft-load combination’ means the combination of a rotorcraft and an external-load,
including the external load attaching means. Rotorcraft-load combinations are designated as Class A,
Class B, Class C and Class D as follows:
a. Class A rotorcraft-load combination means one in which the external load cannot move
freely, cannot be jettisoned, and does not extend below the landing gear.
b. Class B rotorcraft-load combination means one in which the external load is jettisonable and
is lifted free of land or water during the rotorcraft operation.
c. Class C rotorcraft-load combination means one in which the external load is jettisonable and
remains in contact with land or water during the rotorcraft operation.
d. Class D rotorcraft-load combination means one in which the external load is other than a
Class A, B or C and has been specifically approved by the Authority for that operation.


RPI

Radar position indication (RPI). The visual indication, in
non-symbolic and/or symbolic form, on a radar display of
the position of an aircraft obtained by primary and/or
secondary surveillance radar.


RPM

'rpm’ means revolutions per minute.


RPS

Radar position symbol (RPS). The visual indication, in
symbolic form, on a radar display, of the position of an
aircraft obtained after automatic processing of positional
data derived from primary and/or secondary surveillance
radar.


Runway guard lights

Runway guard lights. A light system intended to caution pilots or vehicle drivers that they are about to enter an active runway.


Runway strip.

Runway strip. A defined area including the runway and stopway, if provided, intended:
a) to reduce the risk of damage to aircraft running off a runway; and
b) to protect aircraft flying over it during take-off or landing operations.


Runway turn pad

Runway turn pad. A defined area on a land aerodrome adjacent to a runway for the purpose of completing a 180-degree turn on
a runway.


Runway visual range

“runway visual range” (RVR) means 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


Runway-holding position

“runway-holding position” means a designated position intended to protect a runway, an
obstacle limitation surface, or an ILS/MLS critical or sensitive area at which taxiing
aircraft or vehicles shall stop and hold, unless otherwise authorised by the aerodrome
control tower to proceed


S

Safe forced landing

“safe forced landing” means an unavoidable landing or ditching with a reasonable
expectancy of no injuries to persons in the aircraft or on the surface or of no significant
damage to property;


Safety recommendation

Safety recommendation. A proposal of an accident investigation authority based on information derived from an investigation,
made with the intention of preventing accidents or incidents and which in no case has the purpose of creating a
presumption of blame or liability for an accident or incident. In addition to safety recommendations arising from accident
and incident investigations, safety recommendations may result from diverse sources, including safety studies.


Safety sensitive personnel

“safety sensitive personnel” means persons who might endanger aviation safety if they
perform their duties and functions improperly, including, but not limited to, flight and
cabin crew members, aircraft maintenance personnel and air traffic controllers;


Sailplane

‘Sailplane’ means a heavier-than-air aircraft that is supported in flight by the dynamic reaction of the
air against its fixed lifting surfaces, the free flight of which does not depend on an engine.


SALS

SALS - Short Approach Lighting System


SARPs

SARPs

Standard and Recommended Practices


Satisfactory evidence

Satisfactory evidence. A set of documents or activities that a Contracting State accepts as sufficient to show compliance with
an airworthiness requirement.


SCI

S.C.I. - Secure Communication Interface


SCPs

SCPs - Special category of passenger(s) Persons requiring special conditions, assistance and/or devices when carried on a flight shall be considered as SCPs


Screening

Screening. The application of technical or other means which are intended to identify and/or detect weapons, explosives or
other dangerous devices, articles or substances which may be used to commit an act of unlawful interference.


Note.— Certain dangerous articles or substances are classified as dangerous goods by Annex 18 and the associated
Technical Instructions for the Safe Transport of Dangerous Goods by Air (Doc 9284) and must be transported in accordance
with those instructions. In addition, the Aviation Security Manual (Doc 8973 — Restricted) provides a list of prohibited items
that must never be carried in the cabin of an aircraft.


Search and rescue (SAR) service

Search and rescue (SAR) service. The performance of distress
monitoring, communication, coordination and search and
rescue functions, initial medical assistance or medical evacuation,
through the use of public and private resources,
including cooperating aircraft, vessels and other craft and
installations.

Search and rescue region (SRR). An area of defined dimensions,
associated with a rescue coordination centre, within
which search and rescue services are provided.


Search and rescue aircraft

Search and rescue (SAR) aircraft. An aircraft provided with
specialized equipment suitable for the efficient conduct of
search and rescue missions.


Search and rescue services unit

Search and rescue services unit. A generic term meaning, as the case may be, rescue coordination centre, rescue subcentre or
alerting post.


Second

Second(s). The duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine
levels of the ground state of the caesium-133 atom.


Security

Security. Safeguarding civil aviation against acts of unlawful interference. This objective is achieved by a combination of
measures and human and material resources.


Security audit. An in-depth compliance examination of all aspects of the implementation of the national civil aviation security
programme.


Security control. A means by which the introduction of weapons, explosives or other dangerous devices, articles or substances
which may be used to commit an act of unlawful interference can be prevented.


Security inspection. An examination of the implementation of relevant national civil aviation security programme
requirements by an airline, airport, or other entity involved in security.


Security equipment

Security equipment. Devices of a specialized nature for use, individually or as part of a system, in the prevention or detection
of acts of unlawful interference with civil aviation and its facilities.


Security restricted area

Security restricted area. Those areas of the airside of an airport which are identified as priority risk areas where in addition to
access control, other security controls are applied. Such areas will normally include, inter alia, all commercial aviation
passenger departure areas between the screening checkpoint and the aircraft, the ramp, baggage make-up areas, including
those where aircraft are being brought into service and screened baggage and cargo are present, cargo sheds, mail centres,
airside catering and aircraft cleaning premises.


Segregated parallel operations

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.


SELCAL

“SELCAL” means a system which permits the selective calling of individual aircraft over
radio-telephone channels linking a ground station with an aircraft;


Self-sustaining powered sailplane

Self-sustaining powered sailplane. A powered aeroplane with available engine power which allows it to maintain level flight
but not to take off under its own power.


Serious incident

Serious incident. An incident involving circumstances indicating that there was a high probability of an accident and associated
with the operation of an aircraft which, in the case of a manned aircraft, takes place between the time any person boards the
aircraft with the intention of flight until such time as all such persons have disembarked, or in the case of an unmanned
aircraft, takes place between the time the aircraft is ready to move with the purpose of flight until such time as it comes to
rest at the end of the flight and the primary propulsion system is shut down.


Note 1.— The difference between an accident and a serious incident lies only in the result.


Note 2.— Examples of serious incidents can be found in ICAO Annex 13, Attachment C.


Serious injury

Serious injury. An injury which is sustained by a person in an accident and which:
a) requires hospitalization for more than 48 hours, commencing within seven days from the date the injury was received;
or
b) results in a fracture of any bone (except simple fractures of fingers, toes or nose); or
c) involves lacerations which cause severe haemorrhage, nerve, muscle or tendon damage; or
d) involves injury to any internal organ; or
e) involves second or third degree burns, or any burns affecting more than 5 per cent of the body surface; or
f) involves verified exposure to infectious substances or injurious radiation.


Shipboard heliport

Shipboard heliport. A heliport located on a ship that may be purpose or non-purpose-built. A purpose-built shipboard heliport
is one designed specifically for helicopter operations. A non-purpose-built shipboard heliport is one that utilizes an area of
the ship that is capable of supporting a helicopter but not designed specifically for that task.


Shoulder

Shoulder. An area adjacent to the edge of a pavement so prepared as to provide a transition between the pavement and the
adjacent surface.


Siemens

Siemens (S). The electric conductance of a conductor in which a current of 1 ampere is produced by an electric potential
difference of 1 volt.


Sievert

Sievert (Sv). The unit of radiation dose equivalent corresponding to 1 joule per kilogram.


SIGMET

SIGMET information. Information issued by a meteorological watch office concerning the occurrence or expected
occurrence of specified en-route weather phenomena which may affect the safety of aircraft operations.


Sign

Sign.
a) Fixed message sign. A sign presenting only one message.
b) Variable message sign. A sign capable of presenting several pre-determined messages or no message, as applicable.


Signal Area

“signal area” means an area on an aerodrome used for the display of ground signals


Significant point

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.


Note.— There are three categories of significant points: ground-based navigation aid, intersection and waypoint. In the
context of this definition, intersection is a significant point expressed as radials, bearings and/or distances from ground-based
navigation aids.


SLOP

SLOP - Strategic Lateral Offset Procedure


Slotted aloha

Slotted aloha. A random access strategy whereby multiple users access the same communications channel independently, but
each communication must be confined to a fixed time slot. The same timing slot structure is known to all users, but there
is no other coordination between the users.


Slush

Slush. Water-saturated snow which with a heel-and-toe slap- down motion against the ground will be displaced with a splatter;
specific gravity: 0.5 up to 0.8.
Note.C Combinations of ice, snow and/or standing water may, especially when rain, rain and snow, or snow is falling,
produce substances with specific gravities in excess of 0.8. These substances, due to their high water/ice content, will have a
transparent rather than a cloudy appearance and, at the higher specific gravities, will be readily distinguishable from slush.


Smoke

Smoke. The carbonaceous materials in exhaust emissions which obscure the transmission of light.

Smoke Number. The dimensionless term quantifying smoke emissions (see 3 of ICAO Annex 16, Appendix 2).


Snow

Snow (on the ground).
a) Dry snow. Snow which can be blown if loose or, if compacted by hand, will fall apart again upon release; specific
gravity: up to but not including 0.35.


b) Wet snow. Snow which, if compacted by hand, will stick together and tend to or form a snowball; specific gravity:
0.35 up to but not including 0.5.


c) Compacted snow. Snow which has been compressed into a solid mass that resists further compression and will hold
together or break up into lumps if picked up; specific gravity: 0.5 and over.


SSALF

SSALF - Simplified Short Approach Lighting System with Sequenced Flashing Lights


SSALR

SSALR - Simplified Short Approach Lighting System with Runway Alignment Indicator Lights


SSALS

SSALS - Simplified Short Approach Lighting System


SSR response

SSR response. The visual indication, in non-symbolic form,
on a radar display, of a response from an SSR transponder
in reply to an interrogation.


Standard isobaric surface

Standard isobaric surface. An isobaric surface used on a worldwide basis for representing and analysing the conditions in
the atmosphere.


State of Design

State of Design. The State having jurisdiction over the organization responsible for the type design.


State of Manufacture

State of Manufacture. The State having jurisdiction over the organization responsible for the final assembly of the aircraft.


State of registry

“state of registry” means the state on whose register the aircraft is entered;

Note.— In the case of the registration of aircraft of an international operating agency on other than a national basis, the
States constituting the agency are jointly and severally bound to assume the obligations which, under the Chicago
Convention, attach to a State of Registry. See, in this regard, the Council Resolution of 14 December 1967 on Nationality and
Registration of Aircraft Operated by International Operating Agencies which can be found in Policy and Guidance Material
on the Economic Regulation of International Air Transport (Doc 9587).


State of the operator

“state of the operator” means the state in which the operator’s principal place of
business is located or, if there is no such place of business, the operator’s permanent
residence


Static load-bearing surface

Static load-bearing surface. A surface capable of supporting the mass of a helicopter situated upon it.


Station declination

Station declination. An alignment variation between the zero degree radial of a VOR and true north, determined at the time the
VOR station is calibrated.


Steradian

Steradian (sr). The solid angle which, having its vertex in the centre of a sphere, cuts off an area of the surface of the sphere
equal to that of a square with sides of length equal to the radius of the sphere.


Stopway

‘Stopway’ means an area beyond the take-off runway, no less wide than the runway and centred
upon the extended centreline of the runway, able to support the aeroplane during an abortive take-off,
without causing structural damage to the aeroplane, and designated by the airport authorities for use
in decelerating the aeroplane during an abortive take-off.


Stores (Supplies)

Stores (Supplies). a) Stores (supplies) for consumption; and b) Stores (supplies) to be taken away.


Stores (Supplies) for consumption. Goods, whether or not sold, intended for consumption by the passengers and the
crew on board aircraft, and goods necessary for the operation and maintenance of aircraft, including fuel and
lubricants

.
Stores (Supplies) to be taken away. Goods for sale to the passengers and the crew of aircraft with a view to being landed.


STPD

‘STPD’ means standard temperature, pressure, dry, i.e. O°C, 760 mmHg and no water vapour.


Subsonic aeroplane

Subsonic aeroplane. An aeroplane incapable of sustaining level flight at speeds exceeding flight Mach number of 1.


Supplemental oxygen

‘Supplemental oxygen’ means the additional oxygen required to protect each occupant against the
adverse effects of excessive cabin altitude and to maintain acceptable physiological conditions.


Switch-over time

Switch-over time (light). The time required for the actual intensity of a light measured in a given direction to fall from 50 per
cent and recover to 50 per cent during a power supply changeover, when the light is being operated at intensities of 25 per
cent or above.


Synthetic training device (STD)

“synthetic training device (STD)” means any one of the following types of
apparatus in which flight conditions are simulated on the ground:

(a) a synthetic training device which provides accurate representation of the
flight-deck of a particular aircraft type to the extent that the mechanical,
electrical, electronic and other aircraft systems control functions, the normal
environment of flight crew members, and the performance and flight
characteristics of the type of aircraft are realistically simulated,

(b) a flight procedures simulator which provides a realistic flight-deck
environment and which simulates instrument responses, simple control
functions of mechanical, electrical, electronic and other aircraft systems, and
the performance and flight characteristics of aircraft of a particular class, or

(c) a basic instrument flight trainer which is equipped with appropriate
instruments and which simulates the flight-deck environment of an aircraft in
flight in instrument flight conditions


T

TAA

Terminal arrival altitude (TAA). The lowest altitude that will provide a minimum clearance of 300 m (1 000 ft) above all
objects located in an arc of a circle defined by a 46 km (25 NM) radius centred on the initial approach fix (IAF), or where
there is no IAF on the intermediate approach fix (IF), delimited by straight lines joining the extremity of the arc to the IF.
The combined TAAs associated with an approach procedure shall account for an area of 360 degrees around the IF.


Take-off Power

Power definitions applicable to engines for aeroplanes and helicopters

‘Take-off Power’ means the output shaft power identified in the performance data for use during
take-off, discontinued approach and baulked landing and limited in use to a continuous period of
not more than 5 minutes,


Take-off Power Rating

Power definitions applicable to engines for aeroplanes and helicopters

‘Take-off Power Rating’ means the test bed minimum acceptance output shaft power as stated
in the engine type certificate data sheet, of series and newly overhauled engines when running
at the declared maximum coolantlcylinder head temperatures and within the appropriate
acceptance limitations.


Take-off safety speed

“Take-off safety speed’ (V2) means a referenced airspeed obtained after lift-off at which the required
one-engine-inoperative climb performance can be achieved.


Target level of safety (TLS)

“target level of safety (TLS)“ means a generic term representing the level of risk
which is considered acceptable in particular circumstances


Taxi/ground idle

Taxi/ground idle. The operating phases involving taxi and idle between the initial starting of the propulsion engine(s) and the
initiation of the take-off roll and between the time of runway turn-off and final shutdown of all propulsion engine(s).


Taxiing Taxying

“taxiing” means the movement of an aircraft on the surface of an aerodrome under its own
power, excluding take-off and landing, and in the case of helicopters including air-taxiing,
that is, operation over the surface of an aerodrome within a height band associated with
ground effect and at speeds associated with taxiing


Taxiway

“taxiway” means 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 including
rapid exit taxiway, that is, a taxiway connected to a runway at an acute angle and designed
to allow landing aeroplanes to turn off at higher speeds than are achieved on other exit
taxiways.

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, including:


a) Aircraft stand taxilane. A portion of an apron designated as a taxiway and intended to provide access to aircraft stands
only.


b) Apron taxiway. A portion of a taxiway system located on an apron and intended to provide a through taxi route across
the apron.


c) Rapid exit taxiway. A taxiway connected to a runway at an acute angle and designed to allow landing aeroplanes to
turn off at higher speeds than are achieved on other exit taxiways thereby minimizing runway occupancy times.


TCAC

Tropical cyclone advisory centre (TCAC). A meteorological centre designated by regional air navigation agreement to
provide advisory information to meteorological watch offices, world area forecast centres and international OPMET
databanks regarding the position, forecast direction and speed of movement, central pressure and maximum surface wind
of tropical cyclones.


TDM

Time division multiplex (TDM). A channel sharing strategy in which packets of information from the same source but with
different destinations are sequenced in time on the same channel.


TDMA

Time division multiple access (TDMA). A multiple access scheme based on time-shared use of an RF channel employing:
(1) discrete contiguous time slots as the fundamental shared resource; and (2) a set of operating protocols that allows
users to interact with a master control station to mediate access to the channel.


TDP

‘TDP’ with respect to rotorcraft means take-off decision point.


Technical Instructions

“Technical Instructions” means the Technical Instructions for the Safe Transport of
Dangerous Goods by Air published by the International Civil Aviation Organisation
(ICAO) as Document No. 9284


Technical Instructions Dangerous Goods

Technical Instructions. The Technical Instructions for the Safe Transport of Dangerous Goods by Air (Doc 9284), approved
and issued periodically in accordance with the procedure established by the ICAO Council


Temporary admission

Temporary admission. The customs procedure under which certain goods can be brought into a customs territory
conditionally relieved totally or partially from payment of import duties and taxes; such goods must be imported for a
specific purpose and must be intended for re-exportation within a specified period and without having undergone any
change except normal depreciation due to the use made of them.


Terminal control area

“terminal control area” means a control area normally established by the appropriate ATS
authority at the confluence of ATS routes in the vicinity of one or more major aerodromes


Terms associated with probabilities

Terms associated with probabilities (for engines):-
NOTE: Because an Effect can only be assessed in relation to a complete aircraft and as, for airworthiness
purposes, each category of Effect is related to a particular frequency of occurrence, the definitions and associated
numerical values are given in aircraft terms (hours in flight).


Frequency of occurrences:-
a ‘Reasonably Probable’ means unlikely to occur often during the operation of each aircraft of
the type but which may occur several times during the total operational life of each aircraft of
the types in which the engine may be installed.


NOTE: Where numerical values are used this may normally be interpreted as a probability in the range
l0-3 to 10-5 per hour of flight.


b. ‘Remote’ means unlikely to occur to each aircraft during its total operational life but may occur
several times when considering the total operational life of a number of aircraft of the type in
which the engine is installed.
NOTE: Where numerical values are used this may normally be interpreted as a probability in the range
10-5 to 10-7 per hour of flight.


c. ‘Extremely Remote’ means unlikely to occur when considering the total operational life of a
number of aircraft of the type in which the engine is installed, but nevertheless, has to be
regarded a being possible.


NOTE: Where numerical values are used this may normally be interpreted as a probability in the range
10-7 to 10-9 per hour of flight.


Terrain

Terrain. The surface of the Earth containing naturally occurring features such as mountains, hills, ridges, valleys, bodies of
water, permanent ice and snow, and excluding obstacles.


Note.— In practical terms, depending on the method of data collection, terrain represents the continuous surface that
exists at the bare Earth, the top of the canopy or something in-between, also known as “first reflective surface”.


Tesla

Tesla (T). The magnetic flux density given by a magnetic flux of 1 weber per square metre.


Threshold time

Threshold time. The range, expressed in time, established by the State of the Operator, to an en-route alternate aerodrome,
whereby any time beyond requires an EDTO approval from the State of the Operator.


Through-flight

Through-flight. A particular operation of aircraft, identified by the operator by the use throughout of the same symbol, from
point of origin via any intermediate points to point of destination.


TLOF

Touchdown and lift-off area (TLOF). A load bearing area on which a helicopter may touch down or lift off.


TMZ

TMZ - Transponder Mandatory Zone


Total cosmic radiation

“total cosmic radiation” means the total of ionising and neutron radiation of galactic
and solar origin


Total vertical error (TVE)

“total vertical error (TVE)” means the vertical geometric difference between the
actual pressure altitude flown by an aircraft and its assigned pressure altitude (flight
level)


Touchdown zone

Touchdown zone. The portion of a runway, beyond the threshold, where it is intended landing aeroplanes first contact the
runway.


Traffic avoidance advice

“traffic avoidance advice” means advice provided by an air traffic services unit specifying
manoeuvres to assist a pilot to avoid a collision


Traffic information

“traffic information” means 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


Traffic information service – broadcast

Traffic information service – broadcast (TIS-B) IN. A surveillance function that receives and processes surveillance data from
TIS-B OUT data sources.


Traffic information service – broadcast (TIS-B) OUT. A function on the ground that periodically broadcasts the surveillance
information made available by ground sensors in a format suitable for TIS-B IN capable receivers.


Note.— This technique can be achieved through different data links. The requirements for Mode S extended squitters are
specified in Annex 10, Volume IV, Chapter 5. The requirements for VHF digital link (VDL) Mode 4 and universal access
transceiver (UAT) are specified in Annex 10, Volume III, Part I.
__________________


Transfer of control point

Transfer of control point. A defined point located along the flight path of an aircraft, at which the responsibility for
providing air traffic control service to the aircraft is transferred from one control unit or control position to the next.


Transit delay

Transit delay. In packet data systems, the elapsed time between a request to transmit an assembled data packet and an
indication at the receiving end that the corresponding packet has been received and is ready to be used or forwarded.


Transition altitude

“transition altitude” means the altitude above which the vertical position of an
aircraft is controlled by reference to flight levels instead of altitudes.


Transition level

“transition level” means the altitude below which the vertical position of an
aircraft is controlled by reference to altitudes instead of flight levels


Travel document

Travel document. A passport or other official document of identity issued by a State or organization, which may be used by
the rightful holder for international travel.


Tributary station

Tributary station. An aeronautical fixed station that may route receive or transmit messages and/or digital data but which does not relay except for the purpose of serving similar
stations connected through it to a communication centre.


Trigger NOTAM

Trigger NOTAM

When an AIP Amendment or an AIP Supplement is published in accordance with AIRAC procedures, a “trigger” NOTAM is originated and promulgated. The intent of this NOTAM is to serve as a reminder in the pre-flight information bulletin (PIB) by signalling the coming into effect of operationally significant permanent or temporary changes to the AIP, thus ensuring that users are aware of changes that may affect their flights. It also serves as a reminder to AIS officers responsible for updating AIP to insert a new AIP Amendment or AIP Supplement in the affected AIP on the amendment or supplement effective date.


Tropical cyclone

Tropical cyclone. Generic term for a non-frontal synoptic-scale cyclone originating over tropical or sub-tropical waters with
organized convection and definite cyclonic surface wind circulation.


True airspeed

‘True airspeed’ means the airspeed of an aircraft relative to undisturbed air. True airspeed is equal
to equivalent airspeed multiplied by (~o/p)½


TSO

‘TSO’ means Technical Standard Order.


Type Certificate

Type Certificate. A document issued by a Contracting State to define the design of an aircraft type and to certify that this
design meets the appropriate airworthiness requirements of that State.


U

Ultimate load

Ultimate load. The limit load multiplied by the appropriate factor of safety.


UN number

UN number. The four-digit number assigned by the United Nations Committee of Experts on the Transport of Dangerous
Goods to identify a substance or a particular group of substances.


Unaccompanied baggage

Unaccompanied baggage. Baggage that is transported as cargo and may or may not be carried on the same aircraft with the
person to whom it belongs.


Unburned hydrocarbons

Unburned hydrocarbons. The total of hydrocarbon compounds of all classes and molecular weights contained in a gas sample,
calculated as if they were in the form of methane.


Unclaimed baggage

Unclaimed baggage. Baggage that arrives at an airport and is not picked up or claimed by a passenger.


Unidentified baggage

Unidentified baggage. Baggage at an airport, with or without a baggage tag, which is not picked up by or identified with a
passenger.


Unit load device

Unit load device (ULD). Any type of freight container, aircraft container, aircraft pallet with a net, or aircraft pallet with a net over an
igloo.
Note.— An overpack is not included in this definition.


Upper-air chart

Upper-air chart. A meteorological chart relating to a specified upper-air surface or layer of the atmosphere.


Usability factor

Usability factor. The percentage of time during which the use of a runway or system of runways is not restricted because of the
cross-wind component.
Note.C Cross-wind component means the surface wind component at right angles to the runway centre line.


V

V Definitions

‘VF1’ means the design flap speed for procedure flight conditions.
*‘VFC/MFC’ means maximum speed for stability characteristics.
‘VFE’ means maximum flap extended speed.

'VFTO’ means final take-off speed.
‘VH’ means maximum speed in level flight with maximum continuous power.
’VLE’ means maximum landing gear extended speed.

‘VLO’ means maximum landing gear operating speed.
‘VLOF’ means lift-off speed.
‘VMC’ means minimum control speed with the critical engine inoperative.
'VMCA' means the minimum control speed, take-off climb.
‘VMCG’ means the minimum control speed, on or near ground.
‘VMCL’ means the minimum control speed, approach and landing.
‘VMO/MMO’ means maximum operating limit speed.
‘VMU’ means minimum unstick speed.
‘VNE’ means never-exceed speed.
‘VR’ means rotation speed.
‘VRA’ means rough airspeed.

VS’ means the stall speed or the minimum steady flight speed at which the aeroplane is controllable.
‘Vso’ means the stall speed or the minimum steady flight speed in the landing configuration.
‘Vs1’ means the stall speed or the minimum steady flight speed obtained in a specified configuration.
’Vs1g’ means the one-g stall speed at which the aeroplane can develop a lift force (normal to the flight
path) equal to its weight.
‘VT’ means maximum aerotow speed (JAR-22 only).
‘VT’ means threshold speed.
a ‘VTMAX’ means maximum threshold speed.

‘VTOSS’ means take-off safety speed for Category A rotorcraft.
‘VW’ means maximum winch-launch speed (JAR-22 only).

'VY' means speed for best rate of climb.
'V1 means take-off decision speed. The maximum speed in the take-off at which the pilot must take the first action (e.9. apply
brakes, reduce thrust, deploy speed brakes) to stop the aeroplane within the accelerate-stop
distance. V1 also means the minimum speed in the take-off, following a failure of the critical engine at
VEF, at which the pilot can continue the take-off and achieve the required height above the take-off
surface within the take-off distance.
'V2' means take-off safety speed.
'V2min means minimum take-off safety speed.
'V3' means steady initial climb speed with all engines operating.


VA

'VA’ means design manoeuvring speed.


VAAC

Volcanic ash advisory centre (VAAC). A meteorological centre designated by regional air navigation agreement to provide
advisory information to meteorological watch offices, area control centres, flight information centres, world area forecast
centres and international OPMET databanks regarding the lateral and vertical extent and forecast movement of volcanic
ash in the atmosphere following volcanic eruptions.


Variable Pitch Propellers

'Variable Pitch Propellers’ means a propeller, the pitch setting of which changes or can be changed,
when the propeller is rotating or stationary. This includes:-


a.) A propeller, the pitch setting of which is directly under the control of the flight crew (controllable
pitch propeller).

b) A propeller, the pitch setting of which is controlled by a governor or other automatic means
which may be either integral with the propeller or a separately mounted equipment and which
may or may not be controlled by the flight crew (constant speed propeller).

c) A propeller, the pitch setting of which may be controlled by a combination of the methods of a.
and b.


VASI TVASI T-VASI

Visual Approach Slope Indicator, and TVASI (T-VASI)

 

       


VB

'VB’ means design speed for maximum gust intensity.


Vc

'VC’ means design cruising speed.


VD/MD

'VD/MD’ means design diving speed.


VDL

VHF digital link (VDL). A constituent mobile subnetwork of the aeronautical telecommunication network (ATN), operating
in the aeronautical mobile VHF frequency band. In addition, the VDL may provide non-ATN functions such as, for
instance, digitized voice


VdMd

VDF/MDF’ means demonstrated flight diving speed.


Vectoring

Vectoring. Provision of navigational guidance to aircraft in the form of specific headings, based on the use of an ATS
surveillance system.


Vef

‘VEF' means the speed at which the critical engine is assumed to fail during take-off.


Vf

‘VF' means design flap speed.


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;


Note: The two distances above have different values in air of a given extinction coefficient
and the latter b) varies with the background illumination. The former a) is represented by
the meteorological optical range (MOR).


Visitor

Visitor. Any person who disembarks and enters the territory of a Contracting State other than that in which that person
normally resides; remains there lawfully as prescribed by that Contracting State for legitimate non-immigrant purposes,
such as touring, recreation, sports, health, family reasons, religious pilgrimages, or business; and does not take up any
gainful occupation during his stay in the territory visited.


Visual approach procedure

Visual approach procedure. A series of predetermined manoeuvres by visual reference, 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, a go-around procedure can be carried out.


VOLMET

VOLMET. Meteorological information for aircraft in flight.
Data link-VOLMET (D-VOLMET). Provision of current aerodrome routine meteorological reports (METAR) and
aerodrome special meteorological reports (SPECI), aerodrome forecasts (TAF), SIGMET, special air-reports not
covered by a SIGMET and, where available, AIRMET via data link.
VOLMET broadcast. Provision, as appropriate, of current METAR, SPECI, TAF and SIGMET by means of continuous
and repetitive voice broadcasts.


Volt

Volt (V). The unit of electric potential difference and electromotive force which is the difference of electric potential between
two points of a conductor carrying a constant current of 1 ampere, when the power dissipated between these points is
equal to 1 watt.


Vs

‘VSR’ means reference stall speed.
‘VSRO’ means reference stall speed in the landing configuration.
‘VSRI’ means reference stall speed in a specific configuration.
‘VSW’ means speed at which onset of natural or artificial stall warning occurs.


W

WAFC

World area forecast centre (WAFC). A meteorological centre designated to prepare and issue significant weather forecasts
and upper-air forecasts in digital form on a global basis direct to States by appropriate means as part of the aeronautical
fixed service.


WAFS

World area forecast system (WAFS). A worldwide system by which world area forecast centres provide aeronautical
meteorological en-route forecasts in uniform standardized formats.


Watt

Watt (W). The power which gives rise to the production of energy at the rate of 1 joule per second.


Way-point

“way-point” means a specified geographical location used to define an area navigation
route or the flight path of an aircraft employing area navigation.


Weber

Weber (Wb). The magnetic flux which, linking a circuit of one turn, produces in it an electromotive force of 1 volt as it is
reduced to zero at a uniform rate in 1 second.


Wet Runway

A runway is considered wet when the runway surface is covered with water, or equivalent, less than
specified in "Contaminated Runway" or when there is sufficient moisture on the runway surface to cause it to
appear reflective, but without significant areas of standing water.


Winching area

Winching area. An area provided for the transfer by helicopter of personnel or stores to or from a ship.


Wypt

Waypoint. A specified geographical location used to define an area navigation route or the flight path of an aircraft employing
area navigation. Waypoints are identified as either:

Fly-by waypoint. A waypoint which requires turn anticipation to allow tangential interception of the next segment of a
route or procedure; or


Flyover waypoint. A waypoint at which a turn is initiated in order to join the next segment of a route or procedure.


Z

Z marker beacon

Z marker beacon. A type of radio beacon, the emissions of which radiate in a vertical cone-shaped pattern.



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