Plain English Meaning
Rules that airlines and commercial operators must follow to make sure their planes can safely climb over and stay above mountains, buildings, and other obstacles during every phase of flight. These rules dictate how heavy the plane can be, how steeply it must climb, and how much room it must leave between itself and obstacles below.
Full Definition
The set of FAA-mandated rules that air carriers operating under 14 CFR Parts 121 and 135 must follow to ensure their aircraft can safely clear terrain and obstacles during takeoff, departure, en route, and landing phases. These requirements specify minimum climb performance, , and margins that must be met based on , , and operating environment.