Instrument flight rules (IFR) are a set of regulations governing aircraft operations. IFR permits flying and navigating by instruments alone in conditions where there is no visual reference outside the aircraft.
Instrument flight rules (IFR) are a set of regulations governing aircraft operations. IFR regulations allow a qualified pilot in a suitably equipped aircraft to fly and navigate using only instruments, without any visual reference outside the aircraft.
IFR may be required because of weather conditions, airspace rules or for other reasons, but a pilot may choose to operate a flight under IFR even when there is no requirement to do so.
IFR is usually contrasted with VFR (visual-flight-rules); all flights operate under either IFR or VFR. IFR should not be confused with imc (instrument meteorological conditions), which are weather conditions in which IFR is required.