Glossary

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A

A/C
Aircraft
AAGR
Annual Average Growth Rate: The average growth each year over a certain period of time.
ABSOLUTE ALTITUDE
The measureable height of an aircraft above the actual terrain.
ABSOLUTE CEILING
The maximum altitude above sea level at which an aircraft can maintain level flight under Standard Air conditions.
ACMI
Leasing operation: One airline (lessor) provides an Aircraft, Crew, Maintenance, and Insurance, (ACMI) to another airline (lessee).
AGL
Above Ground Level, as a measurement of altitude above a specific land mass, and differentiated from MSL.
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. French: aileron small wing, diminutive of aile, from Latin: ala, wing. The word "aisle" also derives from the same root. (Above pic proves that birds invented ailerons long before man did.)
AIR ROUTE TRAFFIC CONTROL CENTER (ARTCC) or "CENTER"
A facility established to provide air traffic control service to aircraft operating on IFR flight plans within controlled airspace and principally during the en route phase of flight. When equipment capabilities and controller workload permit, certain advisory/assistance services may be provided to VFR aircraft.
AIR SPEED INDICATOR
An instrument or device that measures the air speed of an aircraft through an air mass, but not its ground speed.
AIR TRAFFIC CONTROL (ATC)
A service operated by the appropriate authority to promote the safe, orderly, and expeditious flow of air traffic.
AIRFOIL
The shape of any flying surface, but principally a wing, as seen in side view ("cross-section"). Its characteristics are Center of Pressure (CP), DRAG (CD), LIFT (CL), Lift-Drag Ratio (L/D), and Moment (CM).
AIRPORT TRAFFIC CONTROL TOWER (ATCT)
A terminal facility that uses air/ground communications, visual signaling, and other devices to provide ATC services to aircraft operating in the vicinity of an airport or on the movement area. Authorizes aircraft to land or takeoff at the airport controlled by the tower or to transit the Class D airspace area regardless of flight plan or weather conditions (IFR or VFR). A tower may also provide approach control services (radar or non radar).
ALPHABET (PHONETIC)
Devised for reasons of clarity in aviation voice radio, this is the current NATO version in global use: ALFA BRAVO CHARLEY DELTA ECHO FOXTROT GOLF HOTEL INDIA JULIET KILO LIMA MIKE NOVEMBER OSCAR PAPA QUEBEC ROMEO SIERRA TANGO UNIFORM VICTOR WHISKY X-RAY YANKEE ZULU The original, from early in World War 2, was: ABLE BAKER CHARLEY DOG EASY FOX GEORGE HOW ITEM JIG KING LOVE MIKE NAN OBOE PETER QUEEN ROGER SUGAR TARE UNCLE VICTOR WILLIAM X-RAY YOKE ZEBRA
ALTIMETER
An adjustable aneroid
ANGLE OF ATTACK
The acute angle at which a moving airfoil meets the airstream.
ANGLE OF INCIDENCE
The angle at which an airfoil is normally fixed in relation to the longitudinal axis of an aircraft.
ANHEDRAL
The downward angle of a wing in relation to a horizontal cross
APPROACH CONTROL
see RADIO NAVIGATION
APRON
The hard
APU
Auxiliary power unit
ARM
In aircraft weight and balance, as well as load distribution, it is the distance from the CENTER OF GRAVITY (c/g) to some point. For computations, arms measured forward from the c/g are positive (+n) and those measured aft of the c/g are negtive (n).
ASK
Available Seat Kilometres: Total seats available for sale x distance (in km).
ASPECT RATIO
The ratio of the span to the chord of an airfoil—a high aspect ratio wing has wide span and narrow chord, and vice-versa for a low aspect ratio wing.
ATC
(1) Aircraft license as Approved Type Certificate, see ATC; (2) AIR TRAFFIC CONTROL.
ATIS
see AUTOMATIC TERMINAL INFORMATION SERVICE
ATK
Available Tonne Kilometres: Total payload available in metric tonnes x distance (in km)
AUTOMATIC TERMINAL INFORMATION SERVICE (ATIS)
Continuous broadcast of recorded non-control information in selected terminal areas, to improve controller effectiveness and to relieve frequency congestion by automating repetitive transmissions of essential but routine information.
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B

Backlog
Typically, total firm orders minus aircraft deliveries
BLEED AIR
Hot air at high pressure, usually from the bypass section of a gas turbine engine, for deicing, heating, and other uses.
BRIC
Brazil, Russia, India, China
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C

CALIBRATED AIRSPEED (CAS)
The indicated airspeed of an aircraft, corrected for position and instrument error. CAS is equal to true airspeed in standard atmosphere at sea level. Compare INDICATED AIRSPEED and TRUE AIRSPEED.
CAMBER
The convex or concave curvature of an airfoil.
CAT
Clear
CAVU
Ceiling and Visibility Unlimited; ideal flying weather.
CEILING
(1) The heights above the earth's surface of the lowest layer of clouds or obscuring phenomena that is reported as "broken," "overcast," or "obscuration," and not classified as "thin" or "partial". (2) The maximum height above sea level in STANDARD AIR attainable by an aircraft under given conditions—see ABSOLUTE CEILING, SERVICE CEILING.
CENTER
An Air Route Traffic Control Center (ARTCC).
CENTER OF GRAVITY (c/g)
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.
Clustering
Partitioning of a data set into subsets, so that the data in each subset share some common traits.
COMPASS COURSE
A bearing as indicated by the horizontal angle between the compass needle and the centerline of the aircraft. A Compass Course is equal to a True Course ± variation and deviation; also equal to a Magnetic Course ± deviation.
COMPASS NORTH
The North point at which a liquid compass needle points, rather than Geographical, or True, North. Compare MAGNETIC NORTH.
CONTRAIL
Trailing streak of condensed water vapor created in the air by heat from an aircraft engine at high altitudes; aka VAPOR TRAIL.
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. Controlled airspace is also that airspace within which all aircraft operators are subject to certain pilot qualifications, operating rules, and equipment requirements in FAR Part 91. For IFR operations in any class of controlled airspace, a pilot must file an IFR flight plan and receive an appropriate ATC clearance. Each B, C, and D airspace area designated for an airport contains at least one primary airport around which the airspace is designated (for specific designations and descriptions of the airspace classes, refer to FAR Part 71).
Converted aircraft
Converted aircraft are aircraft that were initially configured for passenger or combi (passenger + freight) service and have been modified into freighters.
CRAB
A rudder-controlled yawing motion to compensate for a crosswind in maintaining a desired flight path, as in a landing approach.
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D

DECISION HEIGHT
With respect to the operation of aircraft, the height at which point a decision must be made during an instrument approach to either continue the approach or to execute a missed approach [abort].
DEPARTURE CONTROL
see RADIO NAVIGATION
DIHEDRAL
The acute angle, usually upward, between the wing of an airplane and a horizontal cross-section line. Opposite of ANHEDRAL
Discriminant Analysis
Discriminant analysis is a technique for classifying a set of observations into classes. The purpose is to determine the class of an observation based on a set of variables known as predictors or input variables.
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.
DMU
digital mock up
DRAG
The resisting force exerted on an aircraft in its line of flight opposite in direction to its motion. Compare THRUST.
DRIFT
The angle between the heading of an aircraft and its Track [flight path] over the ground as affected by winds.
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E

EIS
entry to service
ELEVATOR
The movable part of a horizontal airfoil which controls the pitch of an aircraft, the fixed part being the STABILIZER.
ELT
Emergency Locator Transmitter
EMPENNAGE
An aircraft's tail group, includes rudder and fin, and stabilizer and elevator. Old French: empenner, to feather an arrow, from Latin penna, feather.
EN ROUTE AIR TRAFFIC CONTROL SERVICES
Air traffic control services provided aircraft on IFR flight plans, generally by centers, when these aircraft are operating between departure and destination terminal areas. When equipment, capabilities, and controller workload permit, certain advisory/assistance services may be provided to VFR aircraft.
ESAD distance
Equivalent Still Air Distance
ETA
Estimated Time of Arrival.
ETD
Estimated Time of Departure.
Express freight
Next-day freight transported by dedicated freighters
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F

FAIRING
An added streamlining structure or auxiliary member, most often of light metal, whose only purpose is to reduce drag. Fairings are not load bearing and, therefore, are not meant to carry any principal air loads placed on the airplane structure.
FAL
Final Assembly Line
FBO
Fixed-Base Operator. A commercial operator supplying fuel, maintenance, flight training, and other services at an airport.
FIN
The fixed part of a vertical airfoil that controls the yaw of an aircraft; the movable part being the RUDDER. Sometime referred to as Vertical Stabilizer.
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. Also see FOWLER FLAP, SLOTTED FLAP, and SPLIT FLAP.
FLARE
A simple 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 LEVEL (FL)
A level of constant atmospheric pressure related to a reference datum of 29.92 inches of mercury. Each is stated in three digits that represent hundreds of feet—flight level 250 represents a barometric altimeter indication of 25,000', flight level 255 as 25,500'.
FLIGHT PLAN
Specified information relating to the intended flight of an aircraft, filed orally or in writing with an FSS or an ATC facility.
FLIGHT SERVICE STATION (FSS)
Air traffic facilities which provide pilot briefing, enroute communications and VFR search and rescue services, assist lost aircraft and aircraft in emergency situations, relay ATC clearances, originate Notices to Airmen, broadcast aviation weather and NAS information, receive and process IFR flight plans, and monitor NAVAIDs. In addition, at selected locations, FSSs provide Enroute Flight Advisory Service (Flight Watch), take weather observations, issue airport advisories, and advise Customs and Immigration of transborder flights.
FOWLER FLAP
Trademark name of a split-flap attached to a wing's trailing edge with a system of tracks and rollers to roll the FLAP backward and downward, increasing the wing area. Named for its inventor, USAAF engineer Harland D Fowler.
FTK
Freight-tonne kilometres: Total freight metric tonnes actually flown X distance (in km)
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G

GDP
Gross domestic product: the total output of goods and services for final use produced by an economy, by both residents and non-residents. This indicator is often used as an independent variable in forecast traffic growth.
GDP at PPP
Gross domestic product at Power Purchasing Parity: It allows a comparison of GDP between countries by the use of a rate of exchange that accounts for price differences across countries, allowing international comparisons of real output and incomes. At the PPP US$ rate, PPP US$1 has the same purchasing power in the domestic economy as $1 has in the United States.
GLASS COCKPIT
Said of an aircraft's control cabin which has all electronic, digital and computer-based, instrumentation.
GLIDE SLOPE
(1) The angle between horizontal and the glide path of an aircraft. (2) A tightly
Global Hub cities
Main global cities and/or large global hubs. These cities are often major centres of population (mega-cities), tourism, business and decisions largely impacting global affairs. Thirty-two global hub cities worldwide are defined in the GMF for the long haul market.
GMF
Global Market Forecast
GPS
Global Positioning System; satellite
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
GROUNDSPEED
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.
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I

IATA city codes
On certain maps cities are designated by a three-letter code. This code is a unique location identifier officially allocated by the International Air Transport Association.
IFE
in flight entertainment
IFR
Instrument Flight Rules, governing flight under instrument meteorological conditions.
ILS
Instrument Landing System. A radar
INDICATED AIRSPEED (IAS)
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.
INSTRUMENT METEOROLOGICAL CONDITIONS (IMC)
Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling less than minima specified for visual meteorological conditions (VMC).
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J

Jigs
ex structure fusée
JOYSTICK
A single floor or roof mounted control stick—sideways movement produces ROLL, and forward/backward movement produces PITCH (rudder pedals produce YAW).
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K

KNOT
One nautical mile, about 1.15 statute miles (6,080'); eg: 125kts = 143.9mph.
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L

LAMINAR-FLOW AIRFOIL
A low-drag airfoil designed to maintain laminar (smooth, continuous) flow over a high percentage of the CHORD about itself. Often relatively thin, especially along the leading edge, with most of its bulk near the center of the chord.
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.
Load factor
For passenger traffic: Number of passenger / Available seats It is a measure of aircraft seat capacity utilisation. For freight, it is the ratio of freight tonnage carried to available payload
LOAD FACTOR (g)
The proportion between lift and weight commonly seen as g (sometimes capitalized)—a unit of force equal to the force of gravity times one.
LONGERON
A principal longitudinal member of a fuselage's framing, usually continuous across a number of supporting points.
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M

Mach or m.
A number representing the ratio of the speed of an object to the speed of sound in the surrounding air or medium in which it is moving.
MARKER BEACON
see RADIO NAVIGATION
MEAN SEA LEVEL
see MSL
METAR
Acronym in FAA pilot briefings and weather reports simply means an "aviation routine weather report," but nobody seems certain about the original source. The format was introduced by the French on 1 Jan 1968, but was not adopted by USA and Canada until 1 July 1996, and is thought to be a contraction from MÉTéorologique ("Weather") Aviation Règuliére ("Routine"). FAA and NOAA specifically define METAR as "an approximate translation from the French."
MSL
Mean Sea Level. The average height of the surface of the sea for all stages of tide; used as a reference for elevations, and differentiated from AGL.
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N

NACELLE
A streamlined enclosure or housing to protect something such as the crew, engine, or landing gear. French: nacelle, from Latin, navicella, little ship.
NATIONAL AIRSPACE SYSTEM (NAS)
The common network of US airspace; air navigation facilities, equipment and services, airports or landing areas; aeronautical charts, information and services; rules, regulations and procedures, technical information, and human resources and material. Included are system components shared jointly with the military.
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O

O&D (Origin&Destination)
The O&D of a passenger is the point of departure to the final point of destination of her/his air journey.
Organic growth
Growth generated by existing routes.
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P

Passenger and combi aircraft replacement
Passenger and combi (passenger + freight) aircraft that are released by an airline. They can be either recycled into another airlines fleet as passenger aircraft or retired from passenger service. When retired, they are either converted to non-passenger services or definitively withdrawn from use (scrapped).
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.
PAYLOAD
Anything that an aircraft carries beyond what is required for its operation during flight, theoretically that from which revenue is derived, such as cargo and passengers.
PILOT IN COMMAND (PiC)
The pilot responsible for the operation and safety of an aircraft during flight time.
PITCH
(1) Of the three axes in flight, this specifies the vertical action, the up-and-down movement. Compare ROLL and YAW. (2) The angle of a propeller or rotor blade in relation to its arc; also the distance advanced by a blade in one full rotation.
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. The difference in pressures is calibrated as air speed by a panel instrument. Named for French scientist Henri Pitot (1695-1771).
Point to point
Air passengers with origin a point A, and final destination a point B, travel
POSITIVE CONTROL
The separation of all air traffic within designated airspace by air traffic control.
PRC
People
Principal Component Analysis
A way of identifying patterns in data, and expressing the data in such a way to highlight their similarities and differences. PCA looks for combinations that can be used to summarise data, losing in the process as little information as possible.
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R

R&T
research and technology
RADAR APPROACH CONTROL FACILITY (RAPCON)
A terminal ATC facility that uses radar and non-radar capabilities to provide approach control services to aircraft arriving, departing, or transiting airspace controlled by the facility. This facility provides radar ATC services to aircraft operating in the vicinity of one or more civil/military airports in a terminal area. The facility may provide services of a ground-controlled approach (GCA). A radar approach control facility may be operated by FAA or a military service, or jointly. Specific facility nomenclatures are used for administrative purposes only and are related to the physical location of the facility and the operating service generally:
Recycled aircraft
Aircraft resuming service with another airline.
Retired aircraft
Aircraft leaving passenger or combi (passenger + freight) services. They can be then either converted to non-passenger services or definitively withdrawn from use (scrapped).
ROLL
Of the three axes in flight, this specifies the action around a central point. Compare PITCH and YAW.
RPK
Revenue Passenger Kilometres: Total passengers X distance (in km). It is the total number of kilometres travelled by all paying passengers. It is typically the unit being used for passenger traffic forecasts. Therefore to an increasing average distance being flown results an increasing traffic forecast. Note: ASK X Passenger load factor = RPK
RUDDER
The movable part of a vertical airfoil which controls the YAW of an aircraft; the fixed part being the FIN.
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S

Scope clauses
Scope clauses are labour agreements that typically define the size and/or number of aircraft that a carrier or its regional airline partners can operate.
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.
SLATS
Movable vanes or auxiliary airfoils, usually set along the leading edge of a wing but able to be lifted away at certain angles of attack.
SLIPSTREAM
The flow of air driven backward by a propeller or downward by a rotor. Compare DOWNWASH.
SLOTTED FLAP
A flap that, when depressed, exposes a SLOT and increases airflow between itself and the rear edge of the wing.
SMOH
"Since Major Overhaul," an acronym seen in reference to the operating hours, or time remaining, on an engine.
SPLIT FLAP
A FLAP built into the underside of a wing, as opposed to a Full Flap wherein a whole portion of the trailing edge is used.
SPOILER
A long, movable, narrow plate along the upper surface of an airplane wing used to reduce lift and increase drag by breaking or spoiling the smoothness of the airflow.
STABILATOR
A movable horizontal tail that combines the actions of a stabilizer and elevator, increasing longitudinal stability while creating a pitching moment.
STABILIZER
The fixed part of a horizontal airfoil that controls the pitch of an aircraft; the movable part being the ELEVATOR.
STANDARD RATE TURN
A turn in which the heading of an aircraft changes 3° per second, or 360° in two minutes.
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T

TARMAC
(1) A bituminous material used in paving; a trade name for Tar MacAdam. (2) An airport surface paved with this substance, especially a runway or an APRON at a hangar.
TAS
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. Compare CALIBRATED AIR SPEED and INDICATED AIR SPEED.
TCA
see CONTROLLED AIRSPACE
TERMINAL RADAR SERVICE AREA (TRSA)
Airspace surrounding designated airports wherein ATC provides radar vectoring, sequencing, and separation on a full-time basis for all IFR and participating VFR aircraft. Service provided at a TRSA is called Stage III Service. TRSAs are depicted on VFR aeronautical charts. Pilot participation is urged but is not mandatory.
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.
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.
Traffic Flow
Traffic within a defined region or between two specified regions
TRAILING EDGE
The rearmost edge of an AIRFOIL.
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.
TRIKE
Nickname for a weight shift-control aircraft, such as a paraglider.
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.
TRUE AIRSPEED
The speed of an aircraft along its flight path, in respect to the body of air (air mass) through which the aircraft is moving. Also see CALIBRATED AIRSPEED, GROUND SPEED, INDICATED AIRSPEED.
TRUE NORTH
The northern direction of the axis of the Earth; aka "Map North." GEOGRAPHIC NORTH, as opposed to MAGNETIC NORTH.
TURBOJET
An aircraft having a jet engine in which the energy of the jet operates a turbine that in turn operates the air compressor.
TURBOPROP
An aircraft having a jet engine in which the energy of the jet operates a turbine that drives the propeller.
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.
TWILIGHT ZONE
Long before Rod Serling's tv series was this consumer lever definition for a glitch in the ADCOCK RANGE, officially called a Bi-Signal Zone. It was a portion of the overlapping area of a beam where the continuous monotone "on course" signal became temporarily overlayed with the "A" or "N" code signals. Read more here.
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U

ULTRALIGHT
An aeronautical vehicle, operated for sport or recreational purposes, that does not require FAA registration, an airworthiness certificate, or pilot certification. Primarily single-occupant vehicles, although some two-place vehicles are authorized for training purposes. Operation of an ultralight vehicle in certain airspaces requires authorization from ATC.
UNCONTROLLED AIRSPACE
Class G Airspace; airspace not designated as Class A, B, C, D or E.
UNDERCARRIAGE
The landing gear of a land-based aircraft, including struts, frames, and wheels. A very British word that has limited use in the USA.
UNDERSHOOT
To land short of a runwway or planned landing spot. Opposite is OVERSHOOT.
UNICOM
Universal Communication. A common radio frequency (usually 121.0 mHz) used at uncontrolled.
UPWASH
The slight, upward flow of air just prior to its reaching the leading edge of a rapidly moving airfoil.
UPWIND TURN
Long a point of contest among pilots, there is in reality no such thing as far as the airplane is concerned. Proponents claim that airplanes lose air speed when turning upwind, while opponents (and the laws of physics) argue that an airplane, like a boat in a river whose speed is only relative to the water and not the shore, is unaffected within the movement of an air mass and that it loses only ground speed.
USEFUL LOAD
The weight of crew, passengers, fuel, baggage, and ballast, generally excluding emergency or portable equipment and ordnance.
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V

V
Velocity, now used in defining air speeds:
VA
Maneuvering Speed (max structural speed for full control deflection)
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.
VFR ON TOP
Flight in which a cloud ceiling exists but modified VISUAL FLIGHT RULES are in effect if the aircraft travels above the cloud layer.
VISUAL METEOROLOGICAL CONDITIONS (VMC)
Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling equal to or better than specified minima.
VLA
Very Large Aircraft. This category regroups aircraft with a seat capacity above 400 seats.
VLE
Max Landing Gear Extended Speed
VLO
Max Landing Gear Operation Speed
VNE
Never Exceed Speed
VNO
Max Structural Cruising Speed
VOR
VHF OmniRange. A ground-based navigation aid transmitting very high-frequency (VHF) navigation signals 360° in azimuth, on radials oriented from MAGNETIC NORTH. 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.
VORTAC
VOR + TACAN (Tactical Air Navigation); combined radio navigation aids.
VS0
Stalling Speed Landing Configuration
VS1
Stalling Speed in a specified Configuration
VSI
Vertical Speed Indicator. A panel instrument that gauges rate of climb or descent in feet
VX
Best Angle of Climb Speed
VXSE
Best Angle of Climb Speed, one engine out
VY
Best Rate of Climb Speed
VYSE
Best Rate of Climb Speed, one engine out
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W

Wake vortex
Space behind the plane…
WING LOADING
The maximum take
WINGLET
A small, stabilizing, rudderlike addition to the tips of a wing to control or employ air movement.
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Y

Yamoussoukro decision
Liberalization of access to air transport markets in Africa.
YAW
Of the three axes in flight, this specifies the side to side movement of an aircraft on its vertical axis, as in skewing. Compare PITCH and ROLL.
YOKE
The control wheel of an aircraft, akin to a automobile steering wheel.