Aviation glossary · Continuing airworthinessWhat is AD?
Airworthiness Directive
A mandatory instruction issued by an aviation authority to correct an unsafe condition in a type of aircraft, engine or component. Compliance is not optional and is usually bounded by a date, flight hours or cycles.
Why it matters
Directives are revised, superseded and cancelled. The risk is rarely missing a directive outright — it is complying with a revision that has since been replaced, and not noticing.
In AerSynx
The EASA library is synchronised every morning and revisions and supersedures are detected automatically; a superseded directive is raised for an analyst rather than silently replaced. AD tracking →