Definition
The authorized practice of postponing the repair or replacement of inoperative equipment on an aircraft, allowing continued flight operations under specific conditions defined by the Minimum Equipment List (MEL), the FAA-approved Letter of Authorization, or the regulations governing operation with inoperative instruments and equipment under 14 CFR 91.213.
Plain English
Putting off the repair of a broken item on the aircraft, where the rules allow you to keep flying with it broken as long as you follow specific procedures.
Context Anchor
Pilots encounter maintenance deferrals during preflight planning, aircraft logbook review, and decisions about whether an airplane with an item not working may legally be flown.
Derivation
From the Latin differre, meaning 'to carry apart' or 'to put off until later.' A deferral is a delay -- the repair is not skipped, just postponed under controlled conditions.
Why Pilots Care
Determines whether an aircraft can be legally dispatched, directly affecting scheduling, passenger service, and compliance with safety regulations.
Intuition Check
Do not read “deferral” as “we can just ignore it.” In aviation, a maintenance deferral is only acceptable when an approved rule or procedure allows the repair to wait.
Example Sentence 1
The mechanic processed a maintenance deferral for the inoperative landing light, placarded it INOP, and entered the deferral in the aircraft's logbook.
Example Sentence 2
All maintenance deferrals must be logged so the next inspection can verify the repairs were completed on time.