AC 91–57() is an FAA Advisory Circular (AC) (Subject: Exception for Limited Recreational Operations of Unmanned Aircraft ) that provides interim safety guidance to individuals operating unmanned aircraft, commonly known as drones, but inclusive of flying model aircraft, for recreational purposes in the National Airspace System of the United States.

Users are advised to avoid noise sensitive areas such as parks, schools, hospitals, and churches.

Hobbyists are advised not to fly in the vicinity of spectators until they are confident that the model aircraft has been flight tested and proven airworthy.

The FAA expects that hobbyists will operate these recreational model aircraft within visual line-of-sight.

However, under FAA policy, AC 91–57 only applies to modelers, and thus specifically excludes its use by persons or companies for business purposes.