Pilots are really good at shortening pretty much everything in aviation down to an abbreviation that is then used as a word. It’s a very efficient way of communicating if you know what the abbreviations stand for. It’s a very inefficient way of communicating if you don’t know what abbreviations stand for.

ADC – air data computer

ADF – automatic direction finding

ADIZ – air defense identification zones

ADM – aeronautical decision making

AGL – above ground level

AHRS – attitude and heading reference system

AIM – aeronautical information manual

ALD – available landing distance

ALS – approach lighting system

ALSF – approach lighting system with sequenced flashing lights

AME – aviation medical examiner

AMEL – airplane multi engine land

ASEL – airplane single engine land

ATC – air traffic control

ATD – aviation training device

ASOS – automated surface observing system

ATIS – automatic terminal information service

ATP – airplane transport pilot

AWOS – automated weather observing system

CAS – calibrated airspeed

CDI – course deviation indicator

CFI – certified flight instructor

CFII – certified flight instructor – instrument

CFIT – controlled flight into terrain

CLC – course-line computer

CRM – crew resource management

CSIP – cirrus standardized instructor pilot

CTAF – common traffic advisory frequency

DCS – decompression sickness

DME – distance measuring equipment

DPE – dedicated pilot examiner

EAS – equivalent airspeed

EFVS – enhanced flight vision system

EVS – enhanced vision display

FAA – federal aviation administration

FAR – federal aviation regulation

FBO – fixed base operations

FDC – flight data center

FL – flight level

FMS – flight management system

FSS – flight service station

GBAS – ground-based augmentation system

GCO – ground communication outlet

GPS – global positioning system

HAA – height above airport

HAT – height above touchdown zone

HIRL – high intensity runway lights

HSI – horizontal situation indicator

HUD – head-up display

HVOR – high altitude VHF omnidirectional range

IMC – instrument meteorological conditions

IRF – instrument flight rules

ICAO – international civil aviation organization

IAS – indicated airspeed

ILS – instrument landing system

INS– inertial navigation system

ISA – international standard atmospheric

IVSI – instantaneous vertical airspeed

KAIS – knots indicated airspeed

KTAS – knots true airspeed

LAHSO – land and hold short operations

LIRL – low intensity runway lights

LOC – localizer

LVOR – low altitude VHF omnidirectional range

MALSF – medium-intensity approach lighting system with sequenced flashing lights

MEI – multi-engine instructor

METAR – meteorological terminal aviation routine

MFD – multi-function display

MIRL – medium intensity runway lights

MOA – military operations area

MSL – mean sea level

MTR– military training route

NDB – non-directional beacon

NOTAM– notice to airmen

NSA – national security area

NTSB – national transportation and safety board

OAT – outside air temperature

ODALS – omnidirectional approach lighting system

PAPI – precision approach indicator

PBN – performance-based navigation

PFD – primary flight display

PPL – private pilot license

POH – pilot operating handbook

PVASI – pulsating visual approach slope indicator

RAIL – runway alignment indicator lights

RAIM – receiver autonomous integrity monitoring

RCLS – runway centerline lights

REIL – runway end indicator lights

RMI – radio magnetic indicator

RNAV – area navigation

RNP– required navigation performance

SID – standard instrument departure route

SFL – sequenced flashing lights

SRM – single-pilot resource management

SSV – standard service volume

STAR – standard arrival route

STOL – short take off and landing

SVS – synthetic vision system

TACAN – tactical air navigation system

TAS – true airspeed

TAF – terminal area forecast

TCH – threshold crossing height

TDZL – touchdown zone lighting

TFR – temporary flight restriction

TOLD – take off and landing distance

TPA – traffic pattern altitude

TSO – technical standard order

TRSA – terminal radar service area

TVOR – terminal VHF omnidirectional range

UNICOM – universal communications

VASI – vertical approach slope indicator

VMC – visual meteorological conditions

VFR – visual flight rules

VOR – VHF omnidirectional range

VOT – VOR test facility

VORTAC – VHF Omnidirectional Range Tactical Aircraft Control

VSI – vertical speed indicator

WAAS – wide area augmentation system