The problem of constructing an optimal route for overflying unprepared landing pads by the unmanned aerial vehicle (UAV) helicopter type in purpose to choose a useful unprepared landing to make an emergency landing is considered. The description of mathematical models that form the basis of the optimal algorithm of unprepared landing pads overflying is given. The decision to fly to an unprepared landing pad is based on the probabilistic criterion that considers the next following information: the probability of availability of an unprepared landing pad, the probability of failure of the UAV’s helicopter type onboard system, the error of a digital elevation map (DEM) positional information, the error of the UAV’s helicopter type coordinates information and the flight specifications of the UAV helicopter type.The comparison of the computational time of the algorithms of unprepared landing pads overflying is completed. The combined approach to find an optimal route for overflying unprepared landing pads depending on the computational time to solve it is proposed to use. The results of a simulation modelling of the proposed optimal algorithm for the estimation of its efficiency under conditions of variability of parameters of the probabilistic loss function are presented.