A glossary of terms used in relation to aircraft, in alphabetical order.

For specific makes and models, see List of aircraft manufacturers and List of aircraft.

aerodyne

A heavier-than-air craft, deriving its lift from motion.

aeronaut

Pilot or crew of lighter-than-air craft.

aeroplane

A power driven heavier than air aircraft that derives surport in the atmosphere from the reactions of the air on its surfaces that remain fixed under given conditions of flight.(Also airplane)

aerostat

A lighter-than-air craft, such as a balloon or airship. Its lift is caused by buoyancy relative to surrounding air.

ailerons

On an aeroplane, the ailerons are a control surface usually on the trailing edge of the wings. The airlerons are used to control roll.

aircraft

A vehicle that can travel through the air.

airplane

A powered aircraft that derives its lift from the movement of air over fixed lifting surfaces. (Also aeroplane)

airship

A lighter-than-air craft that can be steered and propelled through the air. (Also dirigible)

autogyro

A rotor-craft with unpowered blades - it requires a separate engine to provide forward motion before lift is developed.

aviator

Pilot or crew member of an aircraft.

aviatrix

Female aviator (Obsolete, potentially offensive in modern use.)

balloon

An unpowered lighter-than-air craft.

biplane

An aeroplane with two similar-sized wings (or pairs of wings), exactly or approximately in vertical alignment.

blimp

Non-rigid airship. Its shape is maintained by internal pressure.

Camber

The curved upper surface of the wing.

control surface

Any moveable surface on an aircraft which controls its motion about one of the three principal axes. Ailerons, elevators, and the rudder are examples of control surfaces.

course

The direction in which the aircraft is moving, not to be confused with the heading which is the direction the aircraft is pointing. The course and heading will usually differ because of crosswinds (see crab). The course is also different from the track which is properly the path over the ground that the aircraft has already flown (although course and track are sometimes used synonomously).

crab

A crab is a manoever used to eliminate the drift of an aircraft caused by wind. The pilot will offset the heading of the aircraft from the desired track by a calculated amount, and the aircraft's velocity combined with the wind through vector addition will give a net movement in the desired direction.

chord

The dimension of a wing parallel to the direction of motion.(Compare with span and thickness.)

dihedral angle

The angle that an aeroplane's wings make with a horizontal plane. A larger dihedral angle gives greater roll(lateral) stability at the cost of efficiency.

dirigible

A lighter-than-air craft that can be steered and propelled through the air. From the French word dirigeable meaning steerable. (This term is generally considered out-of-date. The modern term is airship.)

elevons

On an aeroplane, elevons are a single control surface which combines the function of the elevators and ailerons in one. They are usually seen on delta-wing aircraft.

elevators

On an aeroplane, the elevators are a control surface usually on the trailing edge of the horizontal stabilizer. The elevators are used to control pitch.

feather

To rotate the pitch of the propeller blades until they are oriented directily into the airflow, providing the least air resistance and no thrust. The propeller is usually feathered when an engine fails.

glider

An unpowered fixed-wing heavier-than-air craft. (Also sailplane)

heading

The direction in which an aircraft is pointing measure clockwise in degrees from North. Note that this is not necessarily the same as the aircraft's track because of wind.

helicopter

A rotor craft with one or more sets of powered blades.

IFR

Instrument flight rules; a regulatory term describing a flight which may be conducted in conditions where the pilot cannot see outside the aircraft (e.g. in cloud and fog) and must fly only by his instruments. Compare to VFR.

monoplane

An aeroplane with one wing (or pairs of wings).

pitch

A measure of the degree to which an aircraft's nose tilts up or down. Also a measure of the angle of attack of a propeller.

powerplant

A powered aircrafts source of power, usually either a jet engine or a conventional engine and propeller.

roll

Rotation about an axis aligned with the direction in which the aircraft is flying. This axis is also known as the longitudinal axis.

rotorcraft

An aircraft that derives its lift from rotating lifting surfaces (usually called blades)

rudder

On an aeroplane, the rudder is a control surface usually on the trailing edge of the vertical stabilizer or fin. The rudder is used to control yaw.

ruddervators

On an aeroplane, ruddervators are a single control surface which combine the function of the rudder and elevators in one. They are usually seen on V-tail aircraft.

sailplane

An unpowered fixed-wing heavier-than-air craft. (Also glider)

sesquiplane

An aeroplane with two wings (or pairs of wings), where one (often the lower) is significantly smaller than the other in span and/or chord.

slip

A manoevre where an aeroplane pilot rolls the aircraft in one direction with the ailerons and yaws it in the opposite direction with the rudder. This results in the aircraft continuing to move forward but presenting a larger cross-section to the oncoming air - thereby creating drag and causing the aeroplane to lose altitude rapidly in a controlled manner.

span

The dimension of a wing perpendicular to the direction of motion. (Compare with chord and thickness.)

stabilator

On an aeroplane, a stabilator is a surface which combines the function of the horizontal stabilizer and elevators in one by allowing the entire horizontal stabilizer to move and control the pitch of the aircraft.

stall

a condition of an airplane or an airfoil in which lift decreases and drag increases due to the separation of airflow.

track

The path on the ground over which an aircraft has flown. Also used synonomously with course, the direction in which an aircraft is moving relative to the ground. Note that this is not neccesarily the same as the aircraft's heading.

thickness

The vertical dimension of a wing. (Compare with span and chord.)

threshold

The beginning of the part of the runway usable for landing

touchdown zone (TDZ)

The first 3000 feet of the runway or the first third of the runway, whichever is less, measured from the threshold

triplane

An aeroplane with three similar-sized wings (or pairs of wings), exactly or approximately in vertical alignment.

Ultralight

A small, powered aircraft which is extremely light and seats only one or two occupants. Ultralights are popular among hobbyists for being cost-effective and having lenient regulation.

VFR

Visual flight rules; a regulatory term describing flights that are conducted only in conditions where the pilot can see the ground, or in some instances is flying in the free space above a cloud. Compare to IFR.

wing

A lifting surface of an airplane/aeroplane or sailplane.

yaw

Rotation in a horizontal plane about the normally vertical axis - turning to left or right.