Definition
A label, typically reading 'INOP' or 'INOPERATIVE,' affixed in the cockpit next to or on the control, gauge, or switch of a piece of equipment that is not working. It serves as a clear visual notice to the pilot that the item must not be used and, where required by regulation, that the aircraft is being operated under approved provisions for inoperative equipment.
Plain English
A small sign placed on or near a broken instrument or control to tell the pilot it isn't working and shouldn't be used.
Context Anchor
Seen during preflight checks, maintenance signoffs, and decisions about flying an aircraft with equipment that is not working.
Derivation
Inoperative' comes from Latin 'in-' (not) + 'operari' (to work). 'Placard' comes from Old French 'plaquier' (to plaster or stick on). Together: a sign stuck on something to say it isn't working.
Why Pilots Care
It keeps the crew aware of limitations, prevents accidental use of faulty systems, and supports legal and safe flight under deferral rules.
Intuition Check
Do not assume the placard is just a reminder sticker. In this context, it is a required warning label for equipment that must not be used. Do not assume the placard alone approves the flight. The aircraft still has to meet the applicable rules for flying with that item not working.
Example Sentence 1
Before departure, the pilot verified that the broken landing light switch carried an INOPERATIVE placard as required by the MEL.
Example Sentence 2
During the preflight walk-around the pilot confirmed the INOPERATIVE placard was still visible on the deferred navigation light.