Visibility is an important factor in all phases of flight, but especially when the aircraft is manoeuvring on or close to the ground, i.e.
Visibility and/or RVR are reported in routine and special reports using abbreviated plain language, or the Meteorological Terminal Air Report (METAR) or SPECI code at aerodromes, visibility and RVR is also reported in abbreviated plain language in Automated Terminal Information Service (ATIS) transmissions. Visibility is measured in metres (or kilometres) or in Statute Miles, depending on the country concerned. Runway Visual Range (RVR) is the range over which the pilot of an aircraft on the centre line of a runway can see the runway surface markings or the light delineating the runway or identifying its centre line. the greatest distance at which lights in the vicinity of 1000 candelas can be seen and identified against an unlit black background.the greatest safe distance at which a black object of suitable dimensions, situated near the ground, can be seen and recognised when observed against a bright background.Visibility for aeronautical purposes is the greater of: Visibility is affected by the presence of fog, cloud, haze and precipitation. Visibility may vary according to the direction and angle of view, and the height of the observer. Visibility is a measure of the distance at which an object or light can be clearly discerned.