Definition
An aircraft instrument, system, or piece of equipment that is not functioning correctly and cannot be relied upon to provide accurate information or perform its intended task. When a component is identified as inoperative, the pilot must determine whether the flight can legally and safely continue, often by referencing the aircraft's Minimum Equipment List (MEL) or applicable regulations.
Plain English
A part of the aircraft that has stopped working properly. The pilot needs to figure out whether they can keep flying without it, and if so, what extra care is required.
Context Anchor
Seen when discussing aircraft system or instrument failures, such as an analog instrument that stops giving reliable information in flight.
Derivation
From Latin 'in-' meaning 'not' and 'operativus' meaning 'working' or 'producing an effect.' Literally 'not working.' The aviation use is the same idea applied formally to aircraft equipment.
Why Pilots Care
Recognition allows the pilot to select alternate instruments or procedures before the loss of information affects aircraft control.
Intuition Check
Do not assume “inoperative” only means completely dead or blank. A component can be inoperative if it gives wrong, stuck, or unreliable information, even if it still appears to be doing something.
Example Sentence 1
The pilot noted that the attitude indicator was inoperative and reverted to the standby instruments to maintain control.
Example Sentence 2
Preflight inspection revealed an inoperative component in the vertical speed indicator before engine start.