Plain English Meaning

A flight where the pilot flies by the instruments and follows directions from air traffic control, instead of relying on looking out the window. ATC keeps the aircraft separated from other traffic.

Full Definition

A flight conducted in accordance with Instrument Flight Rules, in which the pilot navigates and controls the aircraft primarily by reference to flight instruments rather than by looking outside. The flight is operated under an IFR clearance issued by air traffic control, who provides separation from other IFR traffic and, in controlled airspace, from terrain and obstacles via assigned routes and altitudes.