Using the AIM and FAA Advisory Circulars

Think of your FAA references as three layers. The Code of Federal Regulations (14 CFR) is the binding law — it states the requirement. The Aeronautical Information Manual (AIM) is the FAA’s official guide to basic flight information and air traffic control procedures for the National Airspace System; it explains how things are actually done and contains the fundamentals required to fly in the NAS, plus medical facts, flight-safety information, a Pilot/Controller Glossary of ATC terms, and safety and hazard reporting guidance. The AIM is not itself regulatory, but it reflects operating techniques and procedures that may be requirements in other publications, so pilots treat it as authoritative guidance while relying on the CFR for the legal requirement. The AIM is organized into numbered chapters — for example Chapter 3 is Airspace and Chapter 4 is Air Traffic Control — each divided into sections and paragraphs numbered chapter-section-paragraph (a citation like 3-2-3 means Chapter 3, Section 2, paragraph 3). To find the applicable portion you use the table of contents and that chapter/section structure, and you use the Pilot/Controller Glossary to look up unfamiliar terms and phraseology. The third layer is the FAA advisory circular (AC). The FAA issues ACs to inform the aviation public in a systematic way of nonregulatory material; unless an AC is incorporated into a regulation by reference, its contents are not binding. ACs are numbered in a subject system that corresponds to the subject areas of the CFR, so the leading number points you toward the related regulatory subject: 00-series ACs are general (for example AC 00-45, Aviation Weather Services), and 91-series ACs address the Part 91 operating environment (for example AC 91-74, Pilot Guide: Flight in Icing Conditions). Current ACs are published on the FAA website. In practice a pilot moves between the layers: the CFR to confirm what is required, the AIM for the procedure and phraseology, and the applicable AC for expanded, plain-language guidance on a subject.