Part 91

Small non-commercial aircraft within the United States

Part 121

Large U.S.-based airlines, regional air carriers, and all cargo operators

Part 129

Foreign air carriers or operators who conduct passenger or cargo operations to, from, and transiting the United States

Part 135

Small single aircraft operators to large operators that often provide a network to move cargo to larger Part 121 air carriers

Part 141

Federal Aviation Administration (FAA)-certificated pilot schools

Part 145

Maintenance facilities that are engaged in the maintenance, inspection, and alteration of aircraft and aircraft products