Inoperable instruments and equipment

This regulation governs when Part 121 air carriers can fly with broken instruments or equipment. The basic rule is you cannot take off with inoperable items unless the aircraft has an FAA-approved Minimum Equipment List (MEL) and the airline's operations specifications authorize its use.

The MEL specifies which items can be inoperable and under what conditions the aircraft can still fly safely. The flight crew must have access to this information before every flight, and records of inoperable items must be available to the pilot.

However, certain items can never be included in an MEL: equipment specifically required by the aircraft's type certificate that's essential for safe operation, items required operable by airworthiness directives (unless the AD says otherwise), and equipment required by other Part 121 regulations.

As a special exception, an aircraft may fly with inoperable equipment under a special flight permit for repositioning or repair purposes.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*