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. G-19