Definition
An Advisory Circular (AC) is a non-regulatory document issued by the FAA to provide guidance, recommended practices, methods, or information on a specific aviation subject. ACs are numbered to correspond with the relevant subject area of the Federal Aviation Regulations and, while generally not mandatory, often describe an acceptable means of complying with a regulation.
Plain English
An FAA-published guide that explains how to do something, or how the FAA expects something to be done, without itself being a rule you must follow.
Context Anchor
You will see ACs referenced in FAA handbooks, training materials, maintenance guidance, and discussions about how to comply with FAA rules.
Derivation
‘Advisory’ comes from the Latin advisare, meaning ‘to consider or counsel.’ ‘Circular’ refers to a document circulated for general distribution. Together: a counseling document distributed to the aviation community.
Why Pilots Care
ACs give pilots clear FAA-recommended procedures that support safe operations and help meet regulatory expectations during training, checkrides, and everyday flying.
Intuition Check
Do not assume advisory means unimportant. Here, it means FAA guidance that may strongly shape safe and accepted practice, even when it is not a regulation by itself.
Example Sentence 1
Before her checkride, she reviewed the Advisory Circular on weight and balance to make sure her calculations matched the FAA’s recommended method.
Example Sentence 2
An instructor referred to an AC to clarify proper techniques for entering Class D airspace.