Abstract: In this paper the mathematical models of the airplane approach flight and the GPS navigation observer are presented, The optimal control for the airplane precision landing approach is established, the stable landing window for Airbus-300 (as an example) is determined, the reachable landing category for various GPS positioning precision is calculated, the influence of sampling period on the landing precision is studied and the effects of atmospheric turbulence and side wind on the landing precision are analysed. Some conclusions are drawn from the results of calculation and numerical simulation.

Key words: GPS/INS navigation, random optimal control, airplane landing approach