Applicability

This regulation introduces the performance rules that apply when operating certain categories of airplanes under Part 135 (commuter and on-demand operations). The specific airplane categories covered are listed in § 135.363.

The regulation defines two critical terms for calculating performance:

Effective runway length is the usable distance for landing, measured from where an imaginary obstruction clearance plane intersects the runway centerline to the runway's far end.

Obstruction clearance plane is an imaginary surface sloping upward at 1:20 from the runway. It starts 200 feet wide (100 feet each side of centerline), widens to 500 feet at 1,500 feet from the runway, then continues at that width along the departure or approach path. This plane must clear all obstacles in the area.

These definitions establish how operators calculate available runway length and ensure adequate obstacle clearance when determining if their aircraft can safely operate from a particular runway.

*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.*