General

This regulation directs Part 121 air carriers to different sets of performance rules based on their aircraft type. Reciprocating-engine airplanes must follow §§121.175-121.187, while turbine-engine airplanes follow §§121.189-121.197, with specific exceptions for certain turboprop conversions and older aircraft. Large nontransport category airplanes certificated before 1965 have their own requirements in §§121.199-121.205.

The regulation establishes that performance calculations must use the Airplane Flight Manual data, allowing interpolation when conditions differ from the manual's baseline. Critically, it prohibits takeoffs in reciprocating-engine airplanes exceeding runway-specific weight limits after accounting for temperature corrections.

The FAA may authorize deviations in operations specifications when literal compliance isn't necessary for safety. Additionally, the standard ten-mile obstacle clearance corridor may be reduced to five miles for up to 20 miles when operating VFR or when navigation aids reliably identify terrain and obstacles.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*