Vg diagram. A chart that relates velocity to load factor. It is valid only for a specific weight, configuration and altitude and shows the maximum amount of positive or negative lift the airplane is capable of generating at a given speed. Also shows the safe load factor limits and the load factor that the aircraft can sustain at various speeds. 

V$_{NE}$.  See never-exceed speed. 

V$_{NO}$.  See maximum structural cruising speed. 

V$_{S}$. See stalling speed. 

V$_{X}$.  See best angle-of-climb speed. 

V$_{Y}$.  See best rate-of-climb speed. 

Victor airways.  Airways based on a centerline that extends from one VOR or VORTAC navigation aid or intersection, to another navigation aid (or through several navigation aids or intersections); used to establish a known route for en route procedures between terminal areas. 

Visual approach slope indicator (VASI).  A visual aid of lights arranged to provide descent guidance information during the approach to the runway. A pilot on the correct glideslope will see red lights over white lights. 

Visual flight rules (VFR) . Rules in the Code of Federal Regulations that govern the procedures for conducting flight under visual conditions. 

Visual meteorological conditions (VMC).  Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling meeting or exceeding the minimums specified for VFR. 

VSI. See vertical speed indicator. 

Wake turbulence.  Wingtip vortices that are created when an aircraft generates lift. When an aircraft 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. 

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

Washout. The design of the WSC wing in which a wing is twisted so its angle of attack is less at the tip than at the root. Washout decreases the lift the wing produces at the tip to improve the stall characteristics of the wing. Also called twist. 

Washout strut.  The structural member attached to the leading edges which holds the tip twist for the wing at low or negative angles of attack. 

WCA.  See wind correction angle. 

Weather briefing. Means for pilots to gather information vital to the nature of the flight from a flight service station specialist. 

Weathervane. The tendency to point into the wind. 

Weight. A measure of the heaviness of an object. One of the four main forces acting on an aircraft. The force by which a body is attracted downward 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. 

Weight-Shift Control Aircraft.  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. 

Whip stall. A pitch attitude that is too high for a WSC, at which the tips would stall from flying outside the WSC limitations or flying in extreme/severe turbulence. 

Wind correction angle.  Correction applied to the course to establish a heading so that track will coincide with course. Also called the Crab angle. 

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

Wind drift correction.  Correction applied to the heading of the aircraft necessary to keep the aircraft tracking over a desired track. Also called the wind correction angle or crab angle. 

