Large transport category airplanes: Turbine engine powered: Landing limitations: Alternate airports

This regulation sets landing distance requirements for selecting alternate airports when operating turbine-powered large transport category aircraft under Part 135.

For most Part 135 operators, the aircraft must be able to stop within 70% of the effective runway length (turboprops) or 60% (turbojets) at the expected arrival weight. This distance is measured from a point 50 feet above where the obstruction clearance plane meets the runway, using the performance assumptions from §135.385(b).

Eligible on-demand operators get more flexibility: they can use alternates where the aircraft can stop within 80% of the effective runway length (both turboprops and turbojets), using different performance assumptions from §135.385(f).

These requirements ensure adequate safety margins when planning alternates, accounting for the fact that you might arrive in less-than-ideal conditions. The stricter percentages (compared to destination requirements) provide extra cushion since weather or other factors forcing a diversion may also affect landing performance.

*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.*