The measureable height of an aircraft above the actual terrain.

Mechanical and electrical units mounted on an engine necessary for its operation, such as starter, magnetos, fuel pumps, etc.

Automatic Direction Finding via automated radio.

Attitude indicator

The rate at which ascending air cools and descending air warms, given no heat is added or taken away. The rate for dry air is based on 5.4° F per 1000' altitude (1° per 100 meters); saturated rates vary with barometric pressures and temperatures, and must be adjusted for accuracy.

Yaw generated when the ailerons are used. The lifting wing generates more drag, causing an airplane to yaw toward it.

Attitude Heading and Reference System

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.

The area of airspace over land or water, extending upward from the surface, within which the ready identification, the location, and the control of aircraft are required in the interest of national security. Domestic Air Defense Identification Zone - An ADIZ within the United States along an international boundary of the United States. Coastal Air Defense Identification Zone - An ADIZ over the coastal waters of the United States. Distant Early Warning Identification Zone (DEWIZ) - An ADIZ over the coastal waters of the State of Alaska. ADIZ locations and operating and flight plan requirements for civil aircraft operations are specified in FAR Part 99.

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.

An instrument or device that measures the air speed of an aircraft through an air mass.

An aircraft operator who conducts operations for hire or compensation in accordance with FAR Part 135 in an aircraft with 30 or fewer passenger seats and a payload capacity of 7,500# or less. An air taxi operates on an on demand basis and does not meet the "flight scheduled" qualifications of a commuter

A service operated by the appropriate authority to promote the safe, orderly, and expeditious flow of air traffic.

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).

Trademark name of Alcoa for high-strength sheet aluminum clad with a layer (approximately 5.5% thickness per side) of high-purity aluminum, popularly used in airplane manufacture.

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

An adjustable aneroid-barometic cockpit instrument used to measure an aircraft's altitude.

A SEAPLANE or FLOATPLANE with retractable wheels for use on land, as well. The latter spelling was used in the '20s and '30s but has since fallen out of favor.

The acute angle at which a moving airfoil meets the airstream.

The angle at which an airfoil is normally fixed in relation to the longitudinal axis of an aircraft.

The downward angle of a wing in relation to a horizontal cross-section line; aka CATHEDRAL. SEE DIHEDRAL.

Short for autopilot

The hard-surfaced or paved area around a hangar.

SEE CONTROLLED AIRSPACE

A vacuum-powered panel instrument that displays pitch and roll movements about the lateral and longitudinal axes; aka Attitude Indicator.

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.

SEE CONTROLLED AIRSPACE

SEE AUTOMATIC TERMINAL INFORMATION SERVICE

Automatic rotation of rotary blades from a helicopter in an unpowered glide or the forward movement of an autogyro.

An aircraft, often wingless, with unpowered rotary airfoil blades that auto-rotate and serve as wings as it moves through the air when driven by an engine

Continuous broadcast of recorded noncontrol information in selected terminal areas, to improve controller effectiveness and to relieve frequency congestion by automating repetitive transmissions of essential but routine information.