Visibility [ICAO]

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.
  1. Flight Visibility- The visibility forward from the cockpit of an aircraft in flight.
  2. Ground Visibility- The visibility at an aerodrome as reported by an accredited observer.
  3. Runway Visual Range [RVR]- The range over which the pilot of an aircraft on the centerline of a runway can see the runway surface markings or the lights delineating the runway or identifying its centerline.

Source: Pilot Contoller Glossary (PCG)