Definition
Legally binding notices issued by the FAA that require specific inspections, repairs, modifications, or operating limitations on an aircraft, engine, propeller, or component when an unsafe condition has been identified that is likely to exist or develop in other aircraft of the same design. Compliance with applicable ADs is mandatory before further flight, unless the AD itself permits continued operation under stated conditions.
Plain English
An AD is an FAA order telling owners they must fix or check something on their aircraft because a safety problem has been found. If an AD applies to your aircraft, you must follow it — it is not optional.
Context Anchor
Pilots usually encounter ADs when reviewing maintenance records, checking whether an aircraft is legal to fly, or discussing required maintenance with a mechanic.
Derivation
‘Airworthiness’ combines ‘air’ with ‘worthiness’ — fit or suitable to be in the air. ‘Directive’ comes from the Latin ‘dirigere,’ meaning to direct or guide. Together: a binding instruction that keeps the aircraft fit to fly.
Why Pilots Care
Complying with ADs is required by regulation; failure to do so can ground the aircraft and create serious safety risks from known defects.
Intuition Check
An AD is not a suggestion, service tip, or optional maintenance note. If an AD applies, it is a mandatory requirement that must be complied with as stated.
Example Sentence 1
Before signing off the annual inspection, the mechanic verified that all applicable Airworthiness Directives had been complied with and recorded in the logbook.
Example Sentence 2
Before the cross-country flight, the pilot confirmed with the mechanic that all applicable Airworthiness Directives for the Light-Sport Aircraft were current.