What does the "CAVOK" group in a METAR report indicate?
ACeiling and visibility are OK: meaning visibility ≥10 km, no cloud below 5,000 feet or MSA, and no significant weather.✓
BClear air with very low ozone: indicating stable atmosphere above 10,000 feet.
CCeiling And Visibility OK at reporting station only: conditions apply within 5 nautical miles of the station.
Why →CAVOK (Ceiling And Visibility OK) is an international METAR code meaning: visibility is 10 km or more, there are no clouds below 5,000 feet (or Minimum Sector Altitude if higher), no cumulonimbus at any height, and no significant weather phenomena. CAVOK is used outside the U.S.; domestic METARs typically use SKC (sky clear) or CLR (clear below 12,000 feet) instead.
The trap →CAVOK carries no geographic qualifier: it describes conditions meeting the standard thresholds, not a radius around the station.
Field note →U.S. METARs don't use CAVOK, but international aviation does, and Part 107 knowledge test questions occasionally include international METAR formats. When you see CAVOK, think ideal VFR conditions worldwide.
SOURCE → FAA Aviation Weather Services (AC 00-45H)CHECKED JUL 16ACS III.A.K1MED