Abstract: With the continuous opening of plateau routes, how to ensure the flight safety after the engine failure occurs during the cruising process of the aircraft is a new problem faced by various airlines. Taking the air passenger car A319-115 which flies the "Shigatse/Peace-Beijing/Capital" route as a sample, the method of using the drifting net ceiling to check the minimum safe altitude of the route to judge the safety of overcoming obstacles was applied to design the drifting down procedure after an engine fails during cruise, and define the operating steps of the crew. The results show that: plateau routes have high requirements on aircraft performance; design effective and easy-to-operate emergency descent procedures for engine failure and crew operation steps have a positive effect on plateau flight safety; emergency descent procedures must meet the requirements of aircraft over obstacles; for plateau routes with longer voyages, the study of emergency drifting procedures can be completed in the form of sub-segments. The research results have reference significance in the safe flight of similar plateau routes.