PHAK Glossary — W

See wide area augmentation system.

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.

The boundary area formed when a warm air mass contacts and flows over a colder air mass. Warm fronts cause low ceilings and rain.

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.

See weather and radar processing.

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.

A designated geographical location used for route definition or progress-reporting purposes and is defined in terms of latitude/longitude coordinates.

See wind correction angle.

A device that provides real-time, accurate, predictive, and strategic weather information presented in an integrated manner in the National Airspace System (NAS).

Details surface conditions as derived from METAR and other surface observations.

The force exerted by an aircraft from the pull of gravity.

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.

The angle between the desired track and the heading of the aircraft necessary to keep the aircraft tracking over the desired track.

Indicators that include a wind sock, wind tee, or tetrahedron. Visual reference will determine wind direction and runway in use.

A sudden, drastic shift in windspeed, direction, or both that may occur in the horizontal or vertical plane.

A twice daily forecast that provides wind and temperature forecasts for specific locations in the contiguous United States.

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.

Airfoils attached to each side of the fuselage and are the main lifting surfaces that support the airplane in flight.

The wing root is the part of the wing on a fixedwing aircraft that is closest to the fuselage. Wing roots usually bear the highest bending forces in flight and during landing, and they often have fairings to reduce interference drag between the wing and the fuselage. The opposite end of a wing from the wing root is the wing tip.

The maximum distance from wingtip to wingtip.

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.

A design feature incorporated into some wings to improve aileron control effectiveness at high angles of attack during an approach to a stall.

A measurement of force used to produce movement.

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.