Definition
Aircraft instruments, systems, or components that are not functioning, are missing, or are otherwise unserviceable at the time of flight. Whether the aircraft may legally and safely be flown with these items inoperative is governed by 14 CFR 91.213, which requires the pilot to determine airworthiness using the type certificate, an approved Minimum Equipment List (MEL) if one exists, the Kinds of Operations Equipment List, and the equipment required for the specific flight (day VFR, night VFR, IFR).
Plain English
Parts of the aircraft that are broken, missing, or not working. Before flying, the pilot must check the rules to confirm whether the aircraft is still legal and safe to fly without them, and any unusable item must be properly placarded or removed.
Context Anchor
Pilots encounter this during preflight inspection, aircraft checkout, maintenance writeups, and go/no-go decisions before a flight.
Derivation
Inoperative' comes from Latin 'in-' (not) plus 'operari' (to work). So inoperative literally means 'not working' -- a useful reminder that the term covers anything from a burned-out bulb to a failed vacuum pump, not just dramatic failures.
Why Pilots Care
Directly affects whether a flight can legally and safely depart, influencing go or no-go decisions.
Intuition Check
Do not assume “inoperative” means the whole aircraft cannot fly. It means one or more specific items are not working, and the pilot must verify whether flight is still permitted and safe.
Example Sentence 1
During preflight, the pilot noticed the landing light was inoperative and consulted 14 CFR 91.213 to determine whether the flight could legally continue.
Example Sentence 2
During the inspection the instructor noted the inoperative systems and equipment and explained the impact on the planned lesson.