Definition
The unique identifier assigned by the FAA to each Airworthiness Directive (AD), formatted as year-week-sequence (for example, AD 2024-15-03), used to track, reference, and verify compliance with that specific directive against an aircraft, engine, propeller, or appliance.
Plain English
It is the official tracking number the FAA puts on every Airworthiness Directive, so a specific safety order can be looked up, recorded in the maintenance logs, and checked off as complied with.
Context Anchor
Seen when checking Airworthiness Directives in FAA records, maintenance logbooks, aircraft records, or aircraft ownership paperwork.
Derivation
AD stands for Airworthiness Directive. The numbering format itself — biweekly issue period plus a sequence number — comes from how the FAA publishes ADs in batches throughout the year.
Why Pilots Care
Ensures the aircraft meets mandatory safety standards by identifying which directives apply and have been complied with.
Intuition Check
Do not read “AD number” as the number of directives that apply to the aircraft. Here it means the specific identifying label for one Airworthiness Directive.
Example Sentence 1
Before the flight, the owner checked the logbook to confirm that AD 2023-08-12 had been complied with at the last annual inspection.
Example Sentence 2
Pilots review the AD number during pre-purchase inspections to identify any outstanding airworthiness requirements.