100 Terms Every Aviationist Should Know

No.	Term	Definition
1.	ADF	Automatic direction finder for NDB navigation.
2.	ADIZ	Air defense identification zone requiring special procedures.
3.	ADS-B	Broadcasts aircraft position, velocity, and identification.
4.	AFT CG	Center of gravity behind allowable range.
5.	AGL	Altitude measured above ground level.
6.	Aileron	Control surface for roll about longitudinal axis.
7.	AIM	Aeronautical Information Manual operational guidance.
8.	AIP	Aeronautical Information Publication for a state.
9.	Altimeter setting	Barometric pressure setting for indicated altitude.
10.	AMSL	Altitude above mean sea level.
11.	Angle of attack	Angle between wing chord and relative wind.
12.	Anti-ice	Prevents ice accumulation on surfaces.
13.	Approach plate	Published instrument approach procedure chart.
14.	APU	Auxiliary power unit supplying electrical and bleed air.
15.	ARFF	Airport rescue and firefighting services.
16.	ASOS	Automated surface observing system for weather.
17.	ATC	Air traffic control services for safe separation.
18.	ATIS	Automatic terminal information service broadcast.
19.	Autopilot	System that controls aircraft attitude and path.
20.	AWOS	Automated weather observing system at airports.
21.	Baro-VNAV	VNAV using barometric altitude reference.
22.	Base leg	Traffic pattern leg perpendicular to final.
23.	Block altitude	Altitude range assigned for operations.
24.	Brake fade	Reduced braking effectiveness from heat buildup.
25.	Cabin altitude	Equivalent altitude inside pressurized cabin.
26.	CAF	Change accumulated frost affecting lift.
27.	CAS	Calibrated airspeed corrected for instrument error.
28.	CAT I/II/III	ILS approach categories by minima.
29.	CAVOK	Visibility and cloud conditions are good.
30.	Ceiling	Height of lowest broken/overcast layer.
31.	CFIT	Controlled flight into terrain accident.
32.	CFR	Code of Federal Regulations for aviation rules.
33.	Clearance limit	Farthest point authorized in ATC clearance.
34.	Climb gradient	Altitude gained per distance traveled.
35.	Crosswind component	Wind component perpendicular to runway.
36.	DA/MDA	Decision altitude or minimum descent altitude.
37.	Deice	Removes ice already accumulated on surfaces.
38.	Density altitude	Pressure altitude corrected for nonstandard temperature.
39.	DME	Distance measuring equipment to station.
40.	Downwind leg	Pattern leg parallel to runway opposite direction.
41.	DP	Departure procedure for obstacle clearance and routing.
42.	DR	Dead reckoning navigation using time and heading.
43.	EFB	Electronic flight bag for charts and data.
44.	EICAS	Engine indicating and crew alerting system.
45.	ELT	Emergency locator transmitter for distress signaling.
46.	ETA	Estimated time of arrival.
47.	ETE	Estimated time enroute.
48.	ETOPS	Extended-range twin-engine operational performance standards.
49.	FAF	Final approach fix on instrument approach.
50.	FAR	Federal Aviation Regulations; U.S. operating rules.
51.	FBO	Fixed-base operator providing airport services.
52.	FIKI	Flight into known icing approved equipment.
53.	Final approach	Segment aligned with runway for landing.
54.	Flight level	Altitude referenced to standard pressure 29.92.
55.	FMS	Flight management system for navigation and performance.
56.	FOQA	Flight operations quality assurance data program.
57.	FPM	Feet per minute vertical speed.
58.	Fuel exhaustion	Fuel depleted; engines stop from lack.
59.	Fuel starvation	Fuel aboard but not reaching engine.
60.	GA	General aviation non-airline civil flying.
61.	Glidepath	Vertical guidance for approach descent angle.
62.	GLS	GBAS landing system precision approach guidance.
63.	Go-around	Aborted landing; climb and reconfigure.
64.	GPS	Satellite navigation providing position and time.
65.	GPWS/EGPWS	Ground proximity warning system terrain alerts.
66.	Gust factor	Added airspeed for gusty conditions.
67.	HASI	High intensity approach slope indicator.
68.	Heading	Direction aircraft nose points relative north.
69.	HF	High-frequency radio for long-range communications.
70.	Hold short	Stop before runway or specified point.
71.	Holding pattern	Racetrack maneuver to delay or sequence.
72.	HOT	High occupancy time on runway.
73.	HSI	Horizontal situation indicator navigation display.
74.	IAF	Initial approach fix begins approach segment.
75.	IAS	Indicated airspeed shown on airspeed indicator.
76.	IFR	Instrument flight rules for low visibility.
77.	ILS	Instrument landing system providing lateral and vertical guidance.
78.	IMC	Instrument meteorological conditions requiring instruments.
79.	Intercept	Join a course or radial to track.
80.	ISA	International Standard Atmosphere reference conditions.
81.	Jet stream	High-altitude fast wind band affecting flight.
82.	KIAS	Knots indicated airspeed.
83.	KTS	Knots; nautical miles per hour.
84.	LAHSO	Land and hold short operations on intersecting runways.
85.	LDA	Localizer-type directional aid offset approach.
86.	Liftoff speed	Airspeed at which aircraft leaves ground.
87.	Localizer	ILS lateral guidance aligned with runway.
88.	Mach number	True airspeed divided by speed of sound.
89.	MEL	Minimum equipment list for dispatch with inoperative items.
90.	METAR	Routine aviation weather report.
91.	Minimums	Lowest authorized altitude/visibility for approach.
92.	Missed approach	Published procedure after not landing.
93.	MOA	Military operations area with special activity.
94.	MSA	Minimum safe altitude within sector area.
95.	NDB	Nondirectional beacon radio navigation aid.
96.	NOTAM	Notice to air missions; time-critical information.
97.	OAT	Outside air temperature.
98.	PAPI	Precision approach path indicator lights.
99.	PIC	Pilot in command with final authority.
100.	Pitot-static system	Measures airspeed, altitude, and vertical speed.