Aeronautical Terms beginning with W
Waypoints
Area navigation waypoints are specified geographical locations, or fixes, used to define an area navigation route or the flight path of an aircraft employing area navigation. Waypoints may be any of the following types:predefined, published, floating, user-defined, fly-by, or fly-over.
Waypoint (WP)
A predetermined geographical position used for route/instrument approach definition, progress reports, published VFR routes, visual reporting points or points for transitioning and/or circumnavigating controlled and/or special use airspace, that is defined relative to a VORTAC station or in terms of latitude/longitude coordinates.
Wide Area Augmentation System (WAAS)
A method of navigation based on GPS. Ground correction stations transmit position corrections that enhance system accuracy and add vertical navigation (VNAV) features.
Wake Turbulence
Wingtip vortices that are created when an airplane generates lift. When an airplane generates lift, air spills over the wingtips from the high pressure areas below the wings to the low pressure areas above them. This flow causes rapidly rotating whirlpools of air called wingtip vortices or wake turbulence.
Waste Gate
A controllable valve in the tailpipe of an aircraft reciprocating engine equipped with a turbocharger. The valve is controlled to vary the amount of exhaust gases forced through the turbocharger turbine.
Weathervane
The tendency of the aircraft to turn into the relative wind.
Weight
A measure of the heaviness of an object. The force by which a body is attracted toward the center of the Earth (or another celestial body) by gravity. Weight is equal to the mass of the body times the local value of gravitational acceleration. One of the four main forces acting on an aircraft. Equivalent to the actual weight of the aircraft. It acts downward through the aircraft’s center of gravity toward the center of the Earth. Weight opposes lift.
Weight And Balance
The aircraft is said to be in weight and balance when the gross weight of the aircraft is under the max gross weight, and the center of gravity is within limits and will remain in limits for the duration of the flight.
Wheelbarrowing
A condition caused when forward yoke or stick pressure during takeoff or landing causes the aircraft to ride on the nosewheel alone.
Wind Correction Angle
Correction applied to the course to establish a heading so that track will coincide with course.
Wind Direction Indicators
Indicators that include a wind sock, wind tee, or tetrahedron. Visual reference will determine wind direction and runway in use.
Wind Shear
A sudden, drastic shift in windspeed, direction, or both that may occur in the horizontal or vertical plane.
Windmilling
When the air moving through a propeller creates the rotational energy.
Windsock
A truncated cloth cone open at both ends and mounted on a freewheeling pivot that indicates the direction from which the wind is blowing.
Wing
Airfoil attached to each side of the fuselage and are the main lifting surfaces that support the airplane in flight.
Wing Area
The total surface of the wing (square feet), which includes control surfaces and may include wing area covered by the fuselage (main body of the airplane), and engine nacelles.
Wing Span
The maximum distance from wingtip to wingtip.
Wing Twist
A design feature incorporated into some wings to improve aileron control effectiveness at high angles of attack during an approach to a stall.
Wingtip Vortices
The rapidly rotating air that spills over an airplane’s wings during flight. The intensity of the turbulence depends on the airplane’s weight, speed, and configuration. It is also referred to as wake turbulence. Vortices from heavy aircraft may be extremely hazardous to small aircraft.
Warning area
An area containing hazards to any aircraft not participating in the activities being conducted in the area. Warning areas may contain intensive military training, gunnery exercises, or special weapons testing.
Waypoint
A designated geographical location used for route definition or progress-reporting purposes and is defined in terms of latitude/longitude coordinates.
Weather and radar processor (WARP)
A device that provides real-time, accurate, predictive and strategic weather information presented in an integrated manner in the National Airspace System (NAS).
Weight
The force exerted by an aircraft from the pull of gravity.
Wide area augmentation system (WAAS)
A differential global positioning system (DGPS) that improves the accuracy of the system by determining position error from the GPS satellites, then transmitting the error, or corrective factors, to the airborne GPS receiver.
Wind correction angle (WCA)
The angle between the desired track and the heading of the aircraft necessary to keep the aircraft tracking over the desired track.
Work
A measurement of force used to produce movement.
Working or short-term memory
The portion of the brain that receives information from the sensory register. This portion of the brain can store information in memory for only a short period of time. If the information is determined by an individual to be important enough to remember, it must be coded in some way for transmittal to long-term memory.
Warning area
A warning area is airspace of defined dimensions, extending from 3 nautical miles outward from the coast of the United States, that contains activity that may be hazardous to nonparticipating aircraft. The purpose of such warning areas is to warn nonparticipating pilots of the potential danger. A warning area may be located over domestic or international waters or both.
Weight-shift-control aircraft
A powered aircraft with a framed pivoting wing and a fuselage controllable only in pitch and roll by the pilot’s ability to change the aircraft’s center of gravity with respect to the wing. Flight control of the aircraft depends on the wing’s ability to flexibly deform rather than the use of control surfaces.
Winglet or tip fin
An out-of-plane surface extending from a lifting surface. The surface may or may not have control surfaces.
Wing Chord
A straight-line distance across a wing from leading edge to trailing edge.
Wake turbulence
Turbulence found to the rear of a solid body in motion relative to a fluid. In aviation terminology, the turbulence caused by a moving aircraft.
Wall cloud
The well-defined bank of vertically developed clouds having a wall-like appearance which form the outer boundary of the eye of a well-developed tropical cyclone.
Warm front
Any non-occluded front which moves in such a way that warmer air replaces colder air.
Warm sector
The area covered by warm air at the surface and bounded by the warm front and cold front of a wave cyclone.
Water equivalent
The depth of water that would result from the melting of snow or ice.
Waterspout
A tornado that forms over water.
Water vapor
Water in the invisible gaseous form.
Wave cyclone
A cyclone which forms and moves along a front. The circulation about the cyclone center tends to produce a wavelike deformation of the front.
Weather
The state of the atmosphere, mainly with respect to its effects on life and human activities; refers to instantaneous conditions or short term changes as opposed to climate.
Weather radar
Radar specifically designed for observing weather. Some types are cloud detection radar and storm detection radar.
Weather vane
A wind vane.
Wedge
Same as ridge—an elongated area of relatively high atmospheric pressure; usually associated with and most clearly identified as an area of maximum anticyclonic curvature of the wind flow (isobars, contours, or streamlines).
Wet bulb
Contraction of either wet-bulb temperature or wet-bulb thermometer.
Wet-bulb temperature
The lowest temperature that can be obtained on a wet-bulb thermometer in any given sample of air, by evaporation of water (or ice) from the muslin wick; used in computing dew point and relative humidity.
Wet-bulb thermometer
A thermometer with a muslin-covered bulb used to measure wet-bulb temperature.
Whirlwind
A small, rotating column of air; may be visible as a dust devil.
Willy-willy
A tropical cyclone of hurricane strength near Australia.
Wind
Air in motion relative to the surface of the earth; generally used to denote horizontal movement.
Wind direction
The direction from which wind is blowing.
Wind speed
Rate of wind movement in distance per unit time.
Wind vane
An instrument to indicate wind direction.
Wind velocity
A vector term to include both wind direction and wind speed.
Wind shear
The rate of change of wind velocity (direction and/or speed) per unit distance; conventionally expressed as vertical or horizontal wind shear.
Wake turbulence
Wingtip vortices that are created when an airplane generates lift. When an airplane generates lift, air spills over the wingtips from the high pressure areas below the wings to the low pressure areas above them. This flow causes rapidly rotating whirlpools of air called wingtip vortices or wake turbulence.
Warm front
The boundary area formed when a warm air mass contacts and flows over a colder air mass. Warm fronts cause low ceilings and rain.
Warning area
An area containing hazards to any aircraft not participating in the activities being conducted in the area. Warning areas may contain intensive military training, gunnery exercises, or special weapons testing.
Waste gate
A controllable valve in the tailpipe of an aircraft reciprocating engine equipped with a turbocharger. The valve is controlled to vary the amount of exhaust gases forced through the turbocharger turbine.
Waypoint
A designated geographical location used for route definition or progress-reporting purposes and is defined in terms of latitude/longitude coordinates.
Weather and radar processor (WARP)
A device that provides real-time, accurate, predictive, and strategic weather information presented in an integrated manner in the National Airspace System (NAS).
Weather depiction chart
Details surface conditions as derived from METAR and other surface observations.
Weight
The force exerted by an aircraft from the pull of gravity.
Wide area augmentation system (WAAS)
A differential global positioning system (DGPS) that improves the accuracy of the system by determining position error from the GPS satellites, then transmitting the error, or corrective factors, to the airborne GPS receiver.
Wind correction angle (WCA)
The angle between the desired track and the heading of the aircraft necessary to keep the aircraft tracking over the desired track.
Wind direction indicators
Indicators that include a wind sock, wind tee, or tetrahedron. Visual reference will determine wind direction and runway in use.
Wind shear
A sudden, drastic shift in windspeed, direction, or both that may occur in the horizontal or vertical plane.
Winds and temperature aloft forecast (FD)
A twice daily forecast that provides wind and temperature forecasts for specific locations in the contiguous United States.
Wing area
The total surface of the wing (in square feet), which includes control surfaces and may include wing area covered by the fuselage (main body of the airplane), and engine nacelles.
Wings
Airfoils attached to each side of the fuselage and are the main lifting surfaces that support the airplane in flight.
Wing span
The maximum distance from wingtip to wingtip.
Wingtip vortices
The rapidly rotating air that spills over an airplane’s wings during flight. The intensity of the turbulence depends on the airplane’s weight, speed, and configuration. Also referred to as wake turbulence. Vortices from heavy aircraft may be extremely hazardous to small aircraft.
Wing twist
A design feature incorporated into some wings to improve aileron control effectiveness at high angles of attack during an approach to a stall.
Work
A measurement of force used to produce movement.
World Aeronautical Charts (WAC)
A standard series of aeronautical charts covering land areas of the world at a size and scale convenient for navigation (1:1,000,000) by moderate speed aircraft. Topographic information includes cities and towns, principal roads, railroads, distinctive landmarks, drainage, and relief. Aeronautical information includes visual and radio aids to navigation, airports, airways, restricted areas, obstructions and other pertinent data.
Discontinued on June 25, 2015
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