When the following conditions occur simultaneously:
1. Visibility equal or greater than 10 km
2. No clouds below 5000 ft or below the highest minimum sector safe altitude (MSA), whichever is the greater, and no cumulonimbus clouds at any altitude
3. No precipitation, thunderstorms, shallow fog, or low drifting snow then the term CAVOK is used to replace visibility, RVR, weather, and clouds in meteorologic reports and forecasts.
Note: CAVOK does not mean clear blue skies.