Visual Flight Rules (VFR)--Rules that govern the procedures for conducting flight under visual
conditions. Also see Visual Meteorological Conditions.
Visual Meteorological Conditions (VMC)--Weather conditions in which visual flight rules apply;
expressed in terms of visibility, ceiling height, and aircraft clearance from clouds along the path of
flight. When these criteria do not exist, instrument meteorological conditions prevail and instrument
flight rules must be complied with. Also see Visual Flight Rules.
Vertical Sight Distance--The longitudinal distance visible from one location to another. Usually, a
height above the pavement surface is also defined.
V-STOL--A tilt-rotor Vertical Take-Off and Landing Aircraft, that has the ability to operate as either a
fixed- or rotary-wing aircraft.
--A diagram showing the relative frequency
of the wind
in correlation with
runway configuration and in reference to true north. It provides a graphic analysis to obtain the total
wind coverage for any runway direction.
Wind Direction--The direction from which the wind is blowing in reference to true north.