Plain English Meaning

Weather that is too poor to fly by looking outside. The pilot can no longer rely on what they see through the windscreen and must fly using only the instruments on the panel.

Full Definition

Weather conditions expressed in terms of visibility, distance from cloud, and ceiling that are less than the minimums specified for visual flight. When IMC exists, flight must be conducted by sole reference to the aircraft instruments under instrument flight rules.

Context Anchor

Pilots see IMC in weather reports, flight planning, instrument training, air traffic control discussions, and .