I listen to the aircraft scanner at home for about 6 hours a day (sometimes more), and when I head to the airport, I bring along a small handheld scanner too. People often ask if I can understand the transmissions and do I know what they mean. That got me thinking—I might compile a list of abbreviations and their meanings. Since the list is quite large, I’ll post it over two days.
Navigation & Approach Abbreviation Meaning
ILS - Instrument Landing SystemProvides precision lateral and vertical guidance to an aircraft during an approach and landing.
RNP - Required Navigation PerformanceA type of performance-based navigation that allows aircraft to fly highly accurate routes.
RNAV - Area NavigationAllows aircraft to navigate between defined points without necessarily flying directly over ground-based navigation stations.
VOR - VHF Omnidirectional RangeGround-based radio navigation system that provides bearing information to aircraft.
DME - Distance Measuring EquipmentTells the aircraft its distance from a ground station.
NDB - Non-Directional BeaconA simple radio navigation aid that allows aircraft to determine the direction to a beacon.
GPS - Global Positioning SystemSatellite-based navigation system used to determine aircraft position.
GNSS - Global Navigation Satellite SystemGeneral term for satellite navigation systems such as GPS, Galileo and GLONASS.
LPV - Localizer Performance with Vertical Guidance
GPS-based approach providing lateral and vertical guidance similar to an ILS.
LOC - LocalizerProvides lateral guidance during an ILS approach.
GS - Glideslope
Provides vertical guidance during an ILS approach.
MDA - Minimum Descent AltitudeLowest altitude permitted on certain non-precision approaches without required visual reference.
DA/DH - Decision Altitude/Decision HeightPoint during an approach at which the pilot must decide whether to land or go around.
MORA - Minimum Off-Route Altitude
Provides terrain clearance for aircraft operating away from an established route.
Communications Abbreviation MeaningSELCAL - Selective CallingAllows ground stations to alert a specific aircraft by sending a coded signal to the aircraft.
VHF - Very High FrequencyRadio frequency range commonly used for aircraft communications, mainly over land and in short distances.
HF - High FrequencyUsed for long-range communications, particularly over oceans and remote areas.
CPDLC - Controller–Pilot Data Link Communications
Allows ATC and pilots to communicate using text-based digital messages.
ACARS - Aircraft Communications Addressing and Reporting SystemDigital system used to exchange operational messages between aircraft and ground stations.
ATC - Air Traffic Control
The service responsible for managing aircraft movements at airports and in controlled airspace.
ATIS - Automatic Terminal Information Service (on VHF)Continuously broadcasts information such as weather, runway in use and airport conditions.
VOLMET - Meteorological Information for Aircraft in Flight (on HF)Provides weather information to aircraft in flight.
HF - High FrequencyLong-range radio communication, particularly useful over oceans.
SATCOM - Satellite CommunicationsUses satellites for aircraft communications.
Aircraft & Flight Operations
APU - Auxiliary Power Unit
Small turbine engine that provides electrical power and air when the main engines aren't running.
GPU - Ground Power UnitGround equipment that supplies electrical power to an aircraft.
FADEC - Full Authority Digital Engine ControlComputer system that automatically controls an aircraft engine.
FMS - Flight Management SystemComputer system used for navigation, flight planning and performance management.
MCDU - Multipurpose Control and Display Unit
Pilot interface used to operate systems such as the FMS.
EICAS - Engine Indicating and Crew Alerting SystemDisplays engine information and alerts to pilots.
ECAM - Electronic Centralized Aircraft MonitorAirbus system displaying aircraft systems information and warnings.
FBW - Fly-by-WireElectronic system that replaces conventional mechanical flight controls.
TCAS - Traffic Collision Avoidance SystemWarns pilots of nearby aircraft and can issue avoidance instructions.
TAWS - Terrain Awareness and Warning System
Warns pilots about potential terrain conflicts.
GPWS - Ground Proximity Warning SystemWarns pilots when the aircraft is dangerously close to terrain.
Airports & Runways
RWY - Runway
Standard aviation abbreviation for runway.
TWY - Taxiway
Aircraft route connecting runways with aprons and terminals.
APRON - Apron
Area where aircraft park, load, unload and receive servicing.
ILS CAT I
Category I ILS
Precision approach with relatively high minimum visibility and decision height.
ILS CAT II
Category II ILS
Allows approaches in lower visibility than CAT I.
ILS CAT III
Category III ILS
Enables approaches and landings in extremely low visibility, depending on the specific CAT III approval.
PAPI - Precision Approach Path Indicator
Lights beside the runway that help pilots maintain the correct approach angle.
VASIS - Visual Approach Slope Indicator System
Visual system providing approach slope guidance.
RESA - Runway End Safety Area
Area beyond the runway designed to reduce the consequences of an aircraft overrunning or undershooting the runway.
ASDA - Accelerate-Stop Distance Available
Runway length available for an aircraft to accelerate and safely stop.
TORA - Take-Off Run Available
Length of runway available for the ground run during take-off.
TODA - Take-Off Distance Available
TORA plus any suitable clearway.
LDA - Landing Distance Available
Runway length available for an aircraft landing.