Advisory Circular

Advisory Circulars (ACs) are informational documents published by aviation authorities (primarily the FAA) to provide guidance on compliance with regulations, standards, and best practices.

ACs are not legally binding but represent the authority's accepted means of compliance. They cover topics from aircraft maintenance to pilot training and airport design.

• Numbered by subject area (e.g., AC 91-series for general operations)
• Revised periodically to reflect new standards or technology
• Often referenced in practical test standards and training syllabi
• EASA publishes similar guidance as Acceptable Means of Compliance (AMC)