Definition
Airworthiness Directives are legally enforceable regulations issued by the FAA to correct an unsafe condition that exists in an aircraft, engine, propeller, or appliance. When the FAA identifies a defect, design flaw, or safety issue likely to exist in other aircraft of the same type, it issues an AD that mandates specific inspections, repairs, modifications, or operating limitations. Compliance is mandatory before further flight, by a stated deadline, or on a recurring basis, depending on how the AD is written.
Plain English
An Airworthiness Directive is an official FAA order telling owners and operators that something on a particular aircraft or part has been found unsafe and must be fixed, inspected, or limited in how it can be used. Following the directive is not optional — the aircraft is not legal to fly until the directive's requirements are met.
Context Anchor
Pilots encounter ADs when reviewing aircraft records, checking whether an airplane is legal to fly, or learning how the FAA keeps aircraft safe after they are certified.
Derivation
Airworthy' combines 'air' with 'worthy,' meaning fit or suitable for flight. A 'directive' comes from Latin 'dirigere,' to direct or steer. Together the term means an official instruction that must be followed to keep an aircraft fit for flight.
Why Pilots Care
Compliance with ADs is required by law. Non-compliance can result in the aircraft being unairworthy and grounded, and may affect insurance or legal operation.
Intuition Check
Do not read “directive” as a recommendation. In this context, an Airworthiness Directive is a mandatory FAA safety order.
Example Sentence 1
Before buying the used Cessna, the pilot reviewed the maintenance logs to confirm all applicable ADs had been complied with.
Example Sentence 2
An Airworthiness Directive required replacement of the fuel pump on this model after several incidents.