Plain English Meaning

The aircraft has the gear on board — and the required inspections — that allow it to be legally flown in the clouds or in low visibility, relying on instruments instead of looking outside.

Full Definition

Describes an aircraft fitted with the instruments, avionics, and certifications required to be flown legally under Instrument Flight Rules (IFR). This typically includes a functioning attitude indicator, heading indicator, navigation radios suitable for the route, a current pitot-static and transponder check, and any equipment specified by the regulations for the of operation and .