RVR (Runway Visual Range) is considered to be better representation of expected distance that the pilot may acquire visual cues on approach than meteorological office reported horizontal visibility. Effect of lighting intensities and background luminescence play a role when establishing an RVR.
Due to commercial or other reasons RVR may not be available at all the airports and in such cases pilot may derive RVR/CMV-Converted Meteorological Visibility by using mathematical conversions depending upon the type of approach lighting and day/night conditions.
Following table is used to calculate CMV.
Conversion of meteorological visibility to RVR is not be used:
- for takeoff,
- for calculating any other requred RVR minimum less than 800 m,
- for visual/circling approaches,
- or when reported RVR is available