A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Visibility - The ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and prominent lighted objects by night.

a. Flight Visibility−The visibility forward from the cockpit of an aircraft in flight.

b. Ground Visibility−The visibility at an aerodrome as reported by an accredited observer.

c. Runway Visual Range [RVR]−The range over which the pilot of an aircraft on the runway can see the runway surface markings or the

centerline of a lights delineating the runway or identifying its centerline.

Visual approach - An approach by an IFR flight when either part or all of an instrument approach procedure is not completed and the approach is executed in visual reference to terrain.

Visual approach slope indicator - VASI - a system of lights on the side of an airport runway threshold that provides visual descent guidance information during approach. These lights may be visible from up to 8 kilometres (5.0 mi) during the day and up to 32 kilometres (20 mi) or more at night.

visual descent point - VDP - A defined point on the final approach course of a non-precision straight-in approach procedure from which normal descent from the MDA to the runway touchdown point may be commenced, provided the approach threshold of that runway, or approach lights, or other markings identifiable with the approach end of that runway are clearly visible to the pilot.

Visual flight rules - VFR - Rules that govern the procedures for conducting flight under visual conditions. In addition, it is used by pilots and controllers to indicate type of flight plan.

visual meteorological conditions - VMC - Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling equal to or better than specified minima.

VOLMET, or meteorological information for aircraft in flight, is the term applied to a worldwide network of radio stations that broadcast TAF, SIGMET and METAR reports on shortwave frequencies. In some countries, VOLMET stations broadcast on VHF frequencies too