CAVOK

CAVOK (Ceiling And Visibility OK) is a METAR/TAF abbreviation used when all of the following conditions are met simultaneously:

• Visibility is 10 km or more
• No clouds below 5,000 ft or below the highest minimum sector altitude, whichever is greater, and no cumulonimbus or towering cumulus at any level
• No significant weather phenomena (no precipitation, thunderstorms, fog, etc.)

When CAVOK applies, it replaces the visibility, weather, and cloud groups in the METAR report. It indicates excellent visual conditions for flight operations.