Advisory circular

Advisory circular (AC) refers to a type of publication offered by the Federal Aviation Administration (FAA) to provide guidance for compliance with [Airworthiness, pilot certification, operational standards, training standards, and any other rules within the 14 CFR Aeronautics and Space Title.]]. They define acceptable means, but not the only means, of accomplishing or showing compliance with airworthiness regulations. Generally informative in nature, Advisory Circulars are neither binding nor regulatory; yet some have the effect of de facto standards or regulations.

Advisory circulars typically refer to industry standards from SAE and RTCA. Some Advisory circulars are only a few pages long and do little more than reference a recommended standard; for example, AC 20-115B referencing DO-178B. Others, like AC 20-115C, are considerably longer; in this case giving guidance in how to transition from DO-178 revision B to C.

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