Airworthiness Directive (AD)
An Airworthiness Directive (AD) is a legally enforceable regulation issued by Transport Canada (or a foreign authority whose ADs TC recognizes) requiring corrective action on an unsafe condition found in an aircraft, engine, propeller, or appliance. Compliance with applicable ADs is mandatory — there are no exceptions.
Types of ADs
- Emergency ADs: Issued immediately for urgent unsafe conditions; effective upon publication — may require immediate grounding
- Priority-one ADs: Require action before the next flight
- Recurring ADs: Require repetitive inspections or maintenance at specified intervals (e.g., every 100 hours)
- One-time compliance ADs: Single action required — inspection, modification, or part replacement
How ADs Are Generated
ADs typically originate from in-service problems reported through the Service Difficulty Reporting System, accident/incident investigation findings, or manufacturer service bulletins that identify safety-critical issues. Foreign ADs (FAA, EASA) are often adopted by TC for aircraft certificated under bilateral agreements.
Responsibility
The aircraft owner/operator is responsible for ensuring all applicable ADs are complied with. The PIC has the legal obligation to confirm airworthiness before flight. An aircraft with a non-complied AD is not airworthy and must not be flown.
On the TC Written Exam
ADs are mandatory, not optional. The aircraft owner is responsible for compliance. Non-compliance renders the aircraft unairworthy. ADs are tracked in the aircraft maintenance records and can be found on the TC website.
Related Terms
See also: Airworthy, Certificate of Airworthiness.