IMC

IMC (Instrument Meteorological Conditions) describes weather conditions below the minimum visibility and ceiling requirements for VFR flight. In IMC, pilots must fly under IFR using cockpit instruments for navigation and aircraft control.

General IMC criteria (varies by airspace class): visibility less than 3 statute miles (5 km) or ceiling below 1,000 ft AGL. The opposite is VMC (Visual Meteorological Conditions).