Runway visual range

RVR is used to determine the landing and takeoff conditions for aircraft pilots, as well as the type of operational visual aids used at the airport.

Because IRVR data are localized information, the values obtained are not necessarily a reliable guide to what a pilot can actually expect to see.

This can easily be demonstrated when obscuration such as fog is variable, different values can apply simultaneously at the same physical point.

Similarly, looking forward he or she cannot see the light in the rollout area, but according to the rollout RVR of 900m, the light there is visible and has already been so for the last 200 m. RVR is used as one of the main criteria for minima on instrument approaches, as in most cases a pilot must obtain visual reference of the runway to land an aircraft.

RVR is also the main criterion used to determine the category of visual aids that are installed at an airport.