What does RVR stand for?

RVR stands for Runway Visual Range, which is a critical measurement in aviation that indicates the horizontal distance a pilot can see down the runway in the direction of takeoff or landing. This measurement is significant for assessing visibility conditions, particularly during low visibility situations, such as fog or heavy rain. RVR is used in conjunction with other weather conditions to determine if it is safe for aircraft to land or take off, as it provides pilots with essential information about their ability to see runway markings and lighting. This knowledge helps ensure the safety of both the aircraft and its passengers during critical phases of flight.

The other options do not accurately represent the standard terminology used in aviation and thus do not convey the same specific meaning related to visibility and operational safety.