Nontransport category airplanes: En route limitations: One engine inoperative

This regulation sets minimum climb performance requirements for Part 121 operators using nontransport category airplanes when flying with one engine inoperative.

The standard rule requires the airplane to maintain at least a 50 feet-per-minute climb rate with the critical engine out, at an altitude of either 1,000 feet above the highest obstacle within five miles of the route or 5,000 feet—whichever is higher. This ensures the aircraft can safely continue flight after an engine failure.

Alternatively, the FAA may approve a drift-down procedure where the airplane descends (assuming 50 fpm worse than published performance) but still clears all obstacles by 1,000 feet. The FAA evaluates weather reliability, navigation aids, terrain, and other operational factors before approving this option.

Performance calculations assume the critical engine is out, the failed engine's propeller is feathered, flaps and gear are optimally configured, operating engines are at maximum continuous power, and fuel weight decreases during flight.

*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.*