Z  Wind shear.  A sudden, drastic shift in windspeed, direction,  or both that may occur in the horizontal or vertical plane.  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.  Zulu time.  A term used in aviation for coordinated universal  time (UTC) which places the entire world on one time standard.  Winds and temperature aloft forecast (FB).  A twice daily  forecast that provides wind and temperature forecasts for  specific locations in the contiguous United States.  Wings.  Airfoils attached to each side of the fuselage and are  the main lifting surfaces that support the airplane in flight.  Wing root.  The wing root is the part of the wing on a fixed- wing 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.  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.  Wind direction indicators.  Indicators that include a  wind sock, wind tee, or tetrahedron. Visual reference will  determine wind direction and runway in use.  Zone of confusion.  Volume of space above the station where  a lack of adequate navigation signal directly above the VOR  station causes the needle to deviate.  G-35 