A
ATC (Air Traffic Control)
A ground-based service provided by controllers who direct aircraft on the ground and through controlled airspace.
View Full Definition →AGL (Above Ground Level)
Altitude expressed in feet or meters measured directly above the underlying ground surface.
View Full Definition →Airspeed
The speed of an aircraft relative to the air mass through which it is flying.
View Full Definition →Altitude
The vertical distance of an object, aircraft, or level measured from a specific reference datum.
View Full Definition →Altimeter Setting (QNH)
The barometric pressure value dialed into an aircraft altimeter to read elevation above mean sea level.
View Full Definition →Angle of Attack (AoA)
The angle between the chord line of an airfoil and the oncoming relative wind.
View Full Definition →Avionics
The electronic systems used on aircraft, including communications, navigation, and flight displays.
View Full Definition →B
Base Leg
A flight path in an airport traffic pattern perpendicular to the landing runway heading.
View Full Definition →Bleed Air
Compressed air extracted from the compressor stage of a turbine engine or APU for onboard systems.
View Full Definition →C
Cabin Altitude
The equivalent atmospheric pressure maintained inside an aircraft passenger cabin.
View Full Definition →Calibrated Airspeed (CAS)
Indicated airspeed corrected for instrument installation and position errors.
View Full Definition →Crosswind
A wind blowing perpendicular or at an angle to the direction of travel or runway heading.
View Full Definition →D
Density Altitude
Pressure altitude corrected for non-standard temperature variations.
View Full Definition →DME (Distance Measuring Equipment)
A radio navigation technology that measures the slant range distance between an aircraft and a ground station.
View Full Definition →Downwind Leg
A flight path parallel to the landing runway flown in the direction opposite to landing.
View Full Definition →F
Final Approach
The last segment of an approach path aligned with the runway centerline leading to touchdown.
View Full Definition →Flaps
High-lift trailing edge aerodynamic devices extended during takeoff and landing.
View Full Definition →Flight Level (FL)
A standard nominal altitude expressed in hundreds of feet above a 1013.25 hPa datum.
View Full Definition →FMS (Flight Management System)
A specialized computer system automating inflight navigation, flight planning, and performance management.
View Full Definition →G
Glideslope (GS)
The vertical guidance component of an Instrument Landing System (ILS).
View Full Definition →Groundspeed (GS)
The actual horizontal speed of an aircraft relative to the Earth surface.
View Full Definition →H
Holding Pattern
A predetermined racetrack maneuver in the sky designed to delay aircraft in controlled airspace.
View Full Definition →I
ILS (Instrument Landing System)
A precision radio navigation system providing lateral and vertical guidance during runway approach.
View Full Definition →K
Knot (kt)
A unit of speed equal to one nautical mile per hour (approximately 1.852 km/h or 1.151 mph).
View Full Definition →L
Localizer (LOC)
The horizontal directional guidance component of an Instrument Landing System (ILS).
View Full Definition →M
Mach Number
The ratio of the speed of an aircraft to the speed of sound in the surrounding medium.
View Full Definition →METAR (Aviation Routine Weather Report)
A standardized format for reporting observed weather conditions at an aerodrome.
View Full Definition →MSL (Mean Sea Level)
The average level of the ocean surface used as a worldwide zero reference altitude.
View Full Definition →N
Nautical Mile (NM)
A unit of distance equal to exactly 1,852 meters, based on one minute of arc of latitude.
View Full Definition →NOTAM (Notice to Air Missions)
A notice filed with an aviation authority to alert pilots of potential hazards along a flight route or at an airport.
View Full Definition →P
Pitot Tube
A pressure-sensitive probe mounted on an aircraft exterior to measure ram air pressure.
View Full Definition →R
Runway
A defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft.
View Full Definition →RVR (Runway Visual Range)
The distance over which a pilot on the centerline can see the runway surface markings or lights.
View Full Definition →S
Slats
Aerodynamic surfaces on the leading edge of an aircraft wing that deploy to increase lift at low speeds.
View Full Definition →Squawk Code
A four-digit octal transponder code assigned to an aircraft by air traffic control for radar identification.
View Full Definition →Stall
A sudden reduction in lift caused by airflow separation when exceeding the critical angle of attack.
View Full Definition →T
Taxiway
A defined path on an aerodrome established for the taxiing of aircraft between runways and terminals.
View Full Definition →TCAS (Traffic Collision Avoidance System)
An airborne electronic system designed to reduce mid-air collisions by interrogating nearby transponders.
View Full Definition →Touchdown Zone (TDZ)
The first portion of a runway beyond the threshold where landing aircraft are intended to contact the surface.
View Full Definition →Transponder
An airborne transmitter-receiver that emits radar responses to ground ATC interrogations.
View Full Definition →V
VOR (VHF Omnidirectional Range)
A short-range terrestrial radio navigation beacon transmitting 360 individual radial tracks.
View Full Definition →W
Waypoint
A specified geographical location defined by coordinates used to define an air navigation route.
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