Airplanes: Turbine engine powered: En route limitations: One engine inoperative

This regulation limits the takeoff weight of turbine-powered airplanes to ensure they can safely continue flying if one engine fails en route. The airplane must be light enough that, using the one-engine-inoperative performance data from its flight manual, it can either:

1. Maintain a positive climb gradient at least 1,000 feet above all terrain within five miles of the route (1,500 feet above the landing airport for newer aircraft), or

2. Descend from cruise altitude to a suitable airport while clearing all terrain by at least 2,000 feet vertically, then maintain a positive climb at 1,000 feet above that airport (1,500 feet for newer aircraft).

The calculation assumes the engine fails at the worst possible point, accounts for adverse winds and fuel consumption, and requires the alternate airport to meet weather minimums. This ensures the flight can safely reach an airport even after losing an engine.

*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.*