- AGL – Above Ground Level, as a measurement of altitude above
a specific land mass, and differentiated from MSL. - ADF
- Automatic Direction Finding via automated radio. - ADI
- Attitude direction indicator. Shows the roll and pitch of the
aircraft. - AFCS – Automatic flight control system that
provides inputs to the fight controls to assist the pilot in
maneuvering and handling the aircraft. - AFT – Referring
to the rear of the aircraft. - AI – Altitude indicator.
Displays the aircraft’s altitude above sea level. - Aileron
- The movable areas of a wingform that control or affect the roll of
an aircraft by working opposite one another-up-aileron on the right
wing and down-aileron on the left wing. - AIM – Airman’s
Information Manual – A primary FAA publication whose purpose is to
instruct airmen about operating in the US airspace system. - ADC – Air Data Computer – A primary sensor-based navigation
data source. - AGR – Air-Ground Ranging – Straight-line
distance from the aircraft to a point on the ground. - ATC
- Air Traffic Control – A service operated by the appropriate
authority to promote the safe, orderly, and expeditious flow of air
traffic. - Airfoil – The shape of the wing when looking
at its profile. Usually a teardrop shape. - Airframe -
The fuselage, booms, nacelles, cowlings, fairings, and airfoil
surfaces of an aircraft. - Airspeed – The speed of an
aircraft relative to its surrounding air mass. See: calibrated
airspeed; indicated airspeed; true airspeed. - Airspeed
Indicator – An onboard instrument which registers velocity
through the air, usually in knots. Different from ground speed. - AIS – Aeronautical Information Service.
- ALS
- Approach light system. A lighting system installed on the approach
end of an airport runway and consists of a series of lightbars,
strobe lights, or a combination of the two that extends outward from
the runway end. - ALT – Short term for Altitude.
- Altimeter – An onboard instrument which senses air pressure
in order to gauge altitude. - Altimeter Setting – The
barometric pressure reading used to adjust a pressure altimeter for
variations in existing atmospheric pressure. - Altitude
- Height of an aircraft, usually with respect to the terrain below. - Angle of Attack – The angle between the chord line of the
wing of an aircraft and the relative wind. - Annual -
Mandatory inspection of airframe and power plant that occurs every
12 months. - AO – Aircraft Operator.
- AOPA
- Aircraft Owner and Pilot’s Association. - APP -
Approach (Control). - Approach Speed – The recommended
speed contained in aircraft manuals used by pilots when making an
approach to landing. - ARCID – Aircraft Identification.
- ATA – Actual Time of Arrival. As opposed to ETA
(Estimated Time of Arrival) used in filing a flight plan.
ATD – Actual Time of Departure. As opposed to ETD (Estimated
Time of Departure) used in filing a flight plan.- ATIS – Automated Terminal Information
Service usually containing vital information on wind
direction, velocity, pressure readings, and active runway
assignment for that particular airport. - Attitude
- The primary aircraft angles in the state vector; pitch,
roll, and yaw. - Attitude Indicator – A vacuum
powered instrument which displays pitch and roll movement
about the lateral and longitudinal axes. - ADF -
Automatic Direction Finding – A basic guidance mode,
providing lateral guidance to a radio station. Equipment
that determines bearing to a radio station.
Autopilot – A method of an automatic flight control
system which controls primary flight controls to meet
specific mission requirements.- Autorotation -
A rotorcraft flight condition in which the lifting rotor is
driven entirely by action of the air when the rotorcraft is
in motion. - AVGAS – Aviation Gasoline (piston aircraft fuel).
- Bernoulli Effect – Airflow over the upper surface of an
airfoil causes suction (lift) because the airstream has been speeded
up in relation to positive pressure of the airflow on the lower
surface. - CAS – Calibrated Airspeed – The indicated
airspeed of an aircraft, corrected for position and instrument
error. CAS is equal to true airspeed in standard atmosphere at sea
level. - Camber – The convex or concave curvature of an
airfoil. - CAT – Clear Air Turbulance.
- CAVU
- Ceiling and Visibility Unlimited; ideal flying weather.
Ceiling – The heights above the earth’s surface of the lowest
layer of clouds or obscuring phenomena that is reported as “broken,”
“overcast,” or “obscured”.- CG – Center of Gravity -
The longitudinal and lateral point in an aircraft where it is
stable; the static balance point. - Chord – The
measurable distance between the leading and trailing edges of a
wingform. - CTAF – Common Traffic Advisory Frequency – A
frequency designed for the purpose of carrying out airport advisory
practices while operating to or from an airport without an operating
control tower. The CTAF may be a UNICOM, Multicom, FSS, or tower
frequency and is identified in appropriate aeronautical
publications. - Controlled Airspace – An airspace of
defined dimensions within which air traffic control service is
provided to IFR flights and to VFR flights in accordance with the
airspace classification. Controlled airspace is a generic term that
covers Class A, B, C, D, and E airspace. - Crabbing – A
rudder-controlled yawing motion to compensate for a crosswind in
maintaining a desired flight path, as in a landing approach. - Dead Reckoning – The process of estimating one’s current
position based upon a previously determined position, or fix, and
advancing that position based upon known speed, elapsed time, and
course. - Deadstick – Descending flight with engine and
propeller stopped. - Departure Stall – A stall in the
takeoff configuration with power. - Deviation (Magnetic)
- The error of a Magnetic Compass due to inherent magnetic
influences in the structure and equipment of an aircraft.
Directional Gyro – A panel instrument providing a gyroscopic
reading of an aircraft’s compass heading.- DME -
Distance Measuring Equipment, a radio navigation device that
determines an aircraft’s distance from a given ground station, as
well as its groundspeed and time to/from the station. - Drag
- The resisting force exerted on an aircraft in its line of flight
opposite in direction to its motion. - Dry Weight – The
weight of an engine exclusive of any fuel, oil, and coolant. - Elevator – The movable part of a horizontal airfoil which
controls the pitch of an aircraft, the fixed part being the
Stabilzer. - ETA – Estimated time of arrival.
ETD – Estimated time of departure.- FBO -
Fixed-Base Operator. A commercial operator supplying fuel,
maintenance, flight training, and other services at an airport. - FAR – Federal Air Regulations.
- Flap – A
movable, usually hinged airfoil set in the trailing edge of an
aircraft wing, designed to increase lift or drag by changing the
camber of the wing or used to slow an aircraft during landing by
increasing lift. - Flare – A control wheel maneuver
performed moments before landing in which the nose of an aircraft is
pitched up to minimize the touchdown rate of speed. - Flight
Envelope – An aircraft’s performance limits, specifically the
curves of speed plotted against other variables to indicate the
limits of speed, altitude, and acceleration that a particular
aircraft cannot safely exceed. - Flight Plan – Specified
information relating to the intended flight of an aircraft, filed
orally or in writing with an FSS or an ATC facility. - FSS -
Flight Service Station – Air traffic facilities which provide
pilot briefing, enroute communications and VFR search and rescue
services, and assist lost aircraft. - Fuselage – An
aircraft’s main body structure housing the flight crew, passengers,
and cargo and to which the wings, tail and, in most single-engined
airplanes, engine are attached. - GA – General Aviation
- That portion of civil aviation which encompasses all facets of
aviation except air carriers holding a certificate of public
convenience and necessity from the Civil Aeronautics Board and large
aircraft commercial operators. - Glass Cockpit – Said of
an aircraft’s control cabin which has all-electronic, digital and
computer-based, instrumentation. - Glider – An unpowered
aircraft capable of maintaining altitude only briefly after release
from tow, then gliding to earth. - Glide Scope – (1) The
angle between horizontal and the glide path of an aircraft. (2) A
tightly-focused radio beam transmitted from the approach end of a
runway indicating the minimum approach angle that will clear all
obstacles; one component of an instrument landing system (ILS). - GPS – Global Positioning System; satellite-based
navigation, rapidly replacing dead reckoning methods.
Gross Weight – The total weight of an aircraft when fully
loaded, including fuel, cargo, and passengers; aka Takeoff Weight.- Ground Control – Tower control, by radioed instructions
from air traffic control, of aircraft ground movements at an
airport. - Ground Effect – Increased lift generated by
the interaction between a lift system and the ground when an
aircraft is within a wingspan distance above the ground. It affects
a low-winged aircraft more than a mid- or high-winged aircraft
because its wings are closer to the ground. - Ground Speed
- The actual speed that an aircraft travels over the ground its
“shadow speed”; it combines the aircraft’s airspeed and the wind’s
speed relative to the aircraft’s direction of flight. - IFR
- Instrument Flight Rules, governing flight under instrument
meteorological conditions. - ILS – Instrument Landing
System. A radar-based system allowing ILS-equipped aircraft to find
a runway and land when clouds may be as low as 200′ (or lower for
special circumstances). - IAS – Indicated Air Speed – A
direct instrument reading obtained from an air speed indicator
uncorrected for altitude, temperature, atmospheric density, or
instrument error. Compare calibrated airspeed and true airspeed. - IMC – Instrument Meterological Conditions -
Meteorological conditions expressed in terms of visibility, distance
from clouds, and ceiling less than minimal specified for visual
meteorological conditions (VMC). - Knot – One nautical
mile, about 1.15 statute miles (6,080′); eg: 125kts = 143.9mph. - Lift – The force exerted on the top of a moving airfoil
as a low-pressure area [vacuum] that causes a wingform to rise.
airfoils do not “float” on air, as is often assumed – like a boat
hull floats on water – but are “pulled up” (lifted) by low air
pressures trying to equalize. - Lift-Drag Ratio – The
lift coefficient of a wing divided by the drag coefficient, as the
primary measure of the efficiency of an aircraft; aka L/D ratio. - Liquid Compass – A non-electronic, calibratable compass
floating in a liquid as a panel instrument; aka wet compass. - Load Factor – The proportion between lift and weight commonly
seen as g (sometimes capitalized) – a unit of force equal to the
force of gravity times one. - LORAN – Long Range Navigation
System – Utilizes timing differences between multiple
low-frequency transmissions to provide accurate latitude/longitude
position information to within 50′. - LTA -
Lighter-than-air craft, generally referring to powered blimps and
dirigibles, but often also includes free balloons.
Magnetic Compass – The most common liquid-type compass, capable
of calibration to compensate for magnetic influences within the
aircraft.- Magnetic Course – Compass course + or -
deviation. - Magnetic North – The magnetic North pole,
located near 71° North latitude and 96° West longitude, that
attracts a magnetic compass which is not influenced by local
magnetic attraction. - MAG – Magneto – An accessory that
produces and distributes a high-voltage electric current for
ignition of a fuel charge in an internal combustion engine. - MSL – Mean Sea Level. The average height off the surface of
the sea for all stages of tide; used as a reference for elevations,
and differentiated from AGL. - METAR – Acronym in FAA
pilot briefings and weather reports simply means an “aviation
routine weather report”. - NDB – Non Directional Beacon
- An LF, MF, or UHF radio beacon transmitting non-directional
signals whereby the pilot of an aircraft equipped with direction
finding equipment can determine his bearing to or from the radio
beacon and “home” on or track to or from the station. - PAR
- Precision Approach Radar, a ground-radar-based instrument approach
providing both horizontal and vertical guidance. - Pattern
- The path of aircraft traffic around an airfield, at an established
height and direction. At tower-controlled fields the pattern is
supervised by radio (or, in non-radio or emergency conditions by red
and green light signals) by air traffic controllers. Flying an
entire pattern is called a ‘Circuit’. - PIC – Pilot in
Command – The pilot responsible for the operation and safety of
an aircraft during flight time. - Pitch – Of the three
axes in flight, this specifies the vertical action, the up-and-down
movement. - Pitot Tube – More accurately but less
popularly used, Pitot-Static Tube, a small tube most often mounted
on the outward leading edge of an airplane wing (out of the
propeller stream) that measures the impact pressure of the air it
meets in flight, working in conjuction with a closed, perforated,
coaxial tube that measures the static pressure. - Roll -
Of the three axes in flight, this specifies the action around a
central point. - Rotorcraft – A heavier-than-air
aircraft that depends principally for its support in flight on the
lift generated by one or more rotors. Includes helicopters and
gyroplanes. - Rudder – The movable part of a vertical
airfoil which controls the YAW of an aircraft; the fixed part being
the fin. - Scud – A low, foglike cloud layer.
Service Ceiling – The height above sea level at which an
aircraft with normal rated load is unable to climb faster than 100′
per minute under Standard Air conditions.- Sideslip – A
movement of an aircraft in which a relative flow of air moves along
the lateral axis, resulting in a sideways movement from a projected
flight path, especially a downward slip toward the inside of a
banked turn. - Sink, Sinking Speed – The speed at which
an aircraft loses altitude, especially in a glide in still air under
given conditions of equilibrium. - Skid – Too shallow a
bank in a turn, causing an aircraft to slide outward from its ideal
turning path. - Slip – Too steep a bank in a turn,
causing an aircraft to slide inward from its ideal turning path. - Slipstream – The flow of air driven backward by a
propeller or downward by a rotor. - Squawk Code – A
four-digit number dialed into his transponder by a pilot to identify
his aircraft to air traffic controllers. - Stabilizer -
The fixed part of a horizontal airfoil that controls the pitch of an
aircraft; the movable part being the elevator. - Stall -
(1) Sudden loss of lift when the angle of attack increases to a
point where the flow of air breaks away from a wing or airfoil,
causing it to drop. (2) A maneuver initiated by the steep raising of
an aircraft’s nose, resulting in a loss of velocity and an abrupt
drop. - TAS – True Air Speed – True Air Speed. Because
an air speed indicator indicates true air speed only under standard
sea-level conditions, true air speed is usually calculated by
adjusting an Indicated Air speed according to temperature, density,
and pressure. - Thrust – The driving force of a
propeller in the line of its shaft or the forward force produced in
reaction to the gases expelled rearward from a jet or rocket engine.
Opposite of drag. - Torque – A twisting, gyroscopic
force acting in opposition to an axis of rotation, such as with a
turning propeller; aka Torsion. - Touch-and-Go – Landing
practice in which an aircraft does not make a full stop after a
landing, but proceeds immediately to another take-off.
Transponder – An airborne transmitter that responds to
ground-based interrogation signals to provide air traffic
controllers with more accurate and reliable position information
than would be possible with “passive” radar; may also provide air
traffic control with an aircraft’s altitude.- Trim Tab
- A small, auxiliary control surface in the trailing edge of a
wingform, adjustable mechanically or by hand, to counteract (“trim”)
aerodynamic forces on the main control surfaces. - Turn &
Bank Indicator – Primary air-driven gyro instrument, a combined
turn indicator and lateral inclinometer to show forces on an
aircraft in banking turns. Also referred to as “needle & ball”
indicator, the needle as the gyro’s pointer and a ball encased in a
liquid-filled, curved tube. - Uncontrolled Airspace -
Class G Airspace; airspace not designated as Class A, B, C, D or E. - UNICOM – Universal Communication – A common radio
frequency (usually 121.0 mHz) used at uncontrolled (non-tower)
airports for local pilot communication. - Useful Load -
The weight of crew, passengers, fuel, baggage, and ballast,
generally excluding emergency or portable equipment and ordnance. - V- Velocity – Used in defining air speeds, listed below:VA = Maneuvering Speed (max structural speed for full
control deflection)
VD = Max Dive Speed (for
certification only)
VFE = Max Flaps Extended Speed
VLE
= Max Landing Gear Extended Speed
VLO = Max Landing Gear
Operation Speed
VNE = Never Exceed Speed
VNO
= Max Structural Cruising Speed
VS0 = Stalling Speed
Landing Configuration
VS1 = Stalling Speed in a
specified Configuration
VX = Best Angle of Climb SpeedVXSE = Best Angle of Climb Speed, one engine out
VY
= Best Rate of Climb Speed
VYSE = Best Rate of Climb
Speed, one engine out - VASI – Visual Approach Slope
Indicator – A system of lights on the side of an airport runway that
provides visual descent guidance information during the approach to
a runway. - Venturi Tube – A small, hourglass-shaped
metal tube, usually set laterally on a fuselage in the slipstream to
create suction for gyroscopic panel instruments. Now outdated by
more sophisticated means. - VFR – Visual Flight Rules
that govern the procedures for conducting flight under visual
conditions. The term is also used in the US to indicate weather
conditions that are equal to or greater than minimum VFR
requirements. Also used by pilots and controllers to indicate a
specific type of flight plan. - VMC – Visual
Meteorological Conditions – Expressed in terms of visibility,
distance from clouds, and ceiling equal to or better than specified
minima. - VOR – VHF OmniRange – A ground-based
navigation aid transmitting very high-frequency (VHF) navigation
signals 360° in azimuth, on radials oriented from magnetic nort. The
VOR periodically identifies itself by Morse Code and may have an
additional voice identification feature. Voice features can be used
by ATC or FSS for transmitting information to pilots. - VSI
- Vertical Speed Indicator. A panel instrument that gauges rate of
climb or descent in feet-per-minute (fpm). Also called the Rate Of
Climb Indicator. - Yaw – Of the three axes in flight,
this specifies the side-to-side movement of an aircraft on its
vertical axis, as in skewing. - Yoke – The control wheel
of an aircraft, akin to a automobile steering wheel.