Plain English Meaning

A flight where the pilot flies by the instruments instead of by looking outside, follows ATC instructions the whole way, and operates under a stricter set of rules that allow flight in clouds and low visibility.

Full Definition

A flight conducted under Instrument Flight Rules, in which the pilot operates the aircraft by reference to cockpit instruments rather than outside visual cues, and navigates and is separated from other traffic under the direction of Air Traffic Control. IFR flight requires an instrument rating, a properly equipped aircraft, and an ATC clearance, and may be conducted in either instrument or visual meteorological conditions.