Aviation Terminology, Abbreviations, Units & Rules of Thumb (BAK)

Terminology

Term

Meaning

Alpha (α) Greek symbol used to represent angle of attack
Beta (β) Angle of sideslip
Arrivals Aircraft joining the circuit
Attitude The nose position (up or down) and wings level or bank (left or right) in relation to the visual horizon and the attitude indicator
AVGAS Aviation gasoline – fuel
Circuit The flightpath of the aircraft around the airport
Clock code A way of describing where something is in relation to the aircraft
Coaming (or glareshield) Overhanging lip above the instrument panel to reduce reflections
Departure Leaving the circuit area. Alternatively, loss of control (departure from controlled flight)
Hangar The aircraft garage
Headset Earphone/microphone set
Holding point Take-off waiting point near the runway
Intercome Communication system for cockpit communication
Knot Rate of speed – one nautical mile per hour
Maintenance release Document that states the aircraft is serviceable for flight
Numbers Show the runway direction to the nearest 10 degrees
Okta 1/8 of the sky
Squelch Adjustment knob to reduce background noise on the radio
Tarmac Aircraft parking area
Threshold The beginning of the runway (marked with white lines called ‘piano keys’ on paved runways)
Unicom Service that may be provided on CTAF frequencies when normal ATC services are not available
Wake turbulence The disturbed air behind a large aircraft
Wind velocity The speed and direction from which the wind is blowing expressed in knots and degrees magnetic
Windshear Varying wind speed and direction at different heights

Abbreviations

Abbreviation

Meaning

AAL

Above aerodrome level

AGL

Above ground level

AI or AH

Attitude indicator or artificial horizon

AIP

Aeronautical information publication

AMSL

Above mean sea level – the altitude indicated on the altimeter when QNH is set on the subscale

ARFOR

Area forecast

ASI

Airspeed indicator

ATC

Air traffic control

AVGAS

Aviation gasoline

BAK

Basic aeronautical knowledge

CASA

Civil Aviation Safety Authority

CAVOK

Ceiling and visibility OK

CFI

Chief flying instructor

CG

Centre of gravity

CHT

Cylinder head temperature

CIR

Command instrument rating

CPL

Commercial pilot licence

CTA

Control area/controlled airspace

CTAF

Common traffic advisory frequency

CTZ

Control zone

DA

Density altitude

DI or DG

Direction indicator or directional gyro

EGT

Exhaust gas temperature

ELT or ELB

Emergency location/locator transmitter

ERSA

En Route Supplement Australia

ETA

Estimated time of arrival

FIR/FIA/FIS

Flight information region/area/service

FPM

Feet per minute (for rate of climb or descent)

GA

General aviation

GAAP

Generation aviation aerodrome procedures

GFPT

General Flying Progress Test

GMT

Greenwich mean time (same as UTC and Z)

GS

Groundspeed (speed of the aircraft relative to a point on the ground)

IAS

Indicated airspeed (the speed of the aircraft as shown on the airspeed indicator)

IFR

Instrument flight rules (CASA definition – the weather is so bad you can’t see out of the window)

ILS

Instrument landing system

IMC

Instrument meteorological conditions

ISA

International Standard Atmosphere

kHz

Kilohertz (radio frequency expressed in thousands of cycles per second)

KIAS

Knots, indicated airspeed

KTAS

Knots, true airspeed

L/D

Lift/drag ratio

LAME

Licensed aircraft maintenance engineer

LMT

Local mean time

LSALT

Lowest safe altitude

MAP

Manifold absolute pressure (together with rpm gives a measure of engine power)

MET

Meteorology

MP

Manifold pressure (same as MAP)

MHz

Megahertz (radio frequency in millions of cycles per second)

NDB

Non-directional beacon

NOTAM

Notice to airmen (advising status of airspace, navigations aid, hazards etc)

NVFR

Night visual flight rules

NVMC

Night visual meteorological conditions (same usage as NVFR)

OCTA

Outside controlled airspace

PAX

Passengers

PIC

Pilot in command

POB

Persons on board

POH

Pilot’s operating handbook

PPL

Private pilot licence

PRD

Prohibited, restricted and danger areas

PSI

Pounds per square inch – pressure

PTT

Press to talk (button for external radio transmissions)

PVT

Private category flight

QNH

Altimeter pressure datum to show vertical distance above local mean sea level

RIS

Radar information service

RBI

Relative bearing indicator (clock code in degrees)

RMI

Radio magnetic indicator

ROC

Rate of climb

ROD

Rate of descent

RPM

Revolutions per minute

RPT

Regular public transport

RWY

Runway

SARTIME

Time after which search begins

SARWATCH

Monitoring of a flight to activate emergency services if not cancelled by a specific time

SIGMET

Significant weather warning

SMC

Surface movement control

TAF

Terminal area forecast

TAS

True airspeed

TR

Track over the ground

TWR

Control tower

Unicom

Universal communications, a secondary function of some CTAF frequencies

USG

US gallon

UTC

Universal coordinated time (same as GMT or Z)

VFG

Visual Flight Guide

VFR

Visual flight rules

VHF

Very high frequency – radio

VMC

Visual meteorological conditions – good weather

VSI

Vertical speed indicator (rate of climb or descent indicator in units of hundreds of feet per minute)

VTC

Visual terminate chart

W/V

Wind velocity – direction from and speed

WAC

World Aeronautical Chart

WX

Weather

XW or X-Wind

Crosswind

Z

Zulu time (same as GMT and UTC)

Units of Measurement – Direction

Heading

Heading in the direction in which the longitudinal axis (the nose) is pointing.

It is usually expressed as a three-figure group with reference to magnetic north.

Bearing & Track

Track is where the aircraft is going. Bearing is the direction to or from a feature or navigation aid.

Bearing can also be expressed relative to the nose of the aircraft via the clock code or as a number of degrees.

Runway Direction

Runway direction is rounded off to the nearest 10 degrees and reduced to a two-figure group by deleting the final 0.

Relative position

Relative position, with reference to a pilot sitting in the cockpit, is often expressed using the clock code.

Distance, Speed & Velocity

The unit for distance is the nautical mile – it is equivalent to 1,852m (1.8km).

The unit for speed is the knot – one knot is one nautical mile per hour.

Wind velocity is described in terms of the direction from which the wind is blowing and its speed in knots.

Vertical Distance

The unit for vertical distance is the foot (approximately 1/3 of a metre).

Altitude is the vertical distance of the aircraft above mean sea level.

Elevation is the vertical distance of the aerodrome reference above mean sea level.

Height is the vertical distance of the aircraft above the ground – called above ground level (AGL) or above aerodrome level (AAL).

Time

Universal Time

The time reference used is coordinated universal time (UTC) also known as Greenwich mean time (GMT) and abbreviated as Zulu time (Z).

Local Time

Local time is the time in the local area (obviously).

Flight Times

Airborne time is the time from takeoff to touchdown.

Engine running time is used for maintenance schedules.

Estimate elapsed time (EET) is the estimated time to complete a leg of a flight.

Time Coding

Usually based on the 24-hour clock.

Weight/Mass

Standard unit is the kilogram (kg).

Will have to convert fuel quantity to weight (litres to kilograms) for performance calculations.

Temperature

Degrees Celsius are the standard units of termperature.

Pressure

Standard unit for atmospheric pressure is the hectopascal (hPa).

Fuel/Oil Volume

Standard unit for fuel quantity is the litre.

To convert value to weight, you need to know the specific gravity (SG) of the fluid. AVGAS has a specific gravity of 0.71 (one litre weights 0.71kg).

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