In the operation of high-altitude/complex terrain airports of western China, one engine inoperative departure(OEI) flight path often extends to hundreds of kilometers or even further, the traditional method of calculating takeoff analysis charts cannot handle such remote obstacle clearance properly. At present, for this problem, there is not only ambiguity in regulations and standards, but also ambiguity in concepts and technical methods. Manufacturer performance software including Boeing and Airbus, do not export 3rd net path length of the takeoff flight path (TOFP), which is necessary for remote obstacle assessment. This article first summarizes the regulations and standards involved in remote obstacles clearance, then proposes a method to calculate TOFP 3rd net length under complex situations, include turn flight, extended 2nd segment and any TOGA/MCT engine thrust combination. By using airbus performance software, A319 aircraft OEI gross departure paths at Lhasa and Mangshi airports are calculated, and the corresponding remote net flight paths under 3 different regulation item are constructed. Combined these remote gross/net paths with the terrain profile within path protection area processed from SRTM 30 m DEM, remote obstacle clearance methods are comprehensive discussed and demonstrated, result shows that different regulations and standards have different applicable scopes, and suggestions have also been made for the revision of relevant regulations and standards.