The article is devoted to the development and research the unmanned aerial vehicle safe flight trajectory calculation and adjustment process imitation model. The main distinguishing feature of the presented model is taking into account the signals of radar stations during the determination and adjustment the location of the aerial vehicle in the case of an autonomous flight and adapting the route based on possible obstacles and deviations. This will improve the safety of the unmanned aerial vehicle flight trajectory. Main studies of path planning methods approaches are analyzed. It was concluded that two-dimensional representation and visualization has disadvantages. Based on disadvantages, the three-dimensional calculated trajectory visualization of a flight mission by an unmanned aerial vehicle simulation model is developed. The simulation model combines the solution of following subtasks: a) modeling a three-dimensional environment with obstacles; b) building an unmanned aerial vehicle trajectory in such environment with avoidance the obstacles. Missions simulation is performed based on developed software system, sequentially, step by step. The following results of the simulation are achieved: 1) a special graphical interface for entering input data and displaying the results is developed; 2) the subsystem for simulation the space for performing a flight task taking into account the location and signals of external influences (for example, radar stations) was developed; 3) the subsystem for flight trajectory simulation calculation and visualization is developed. The software system is built using Delphi based on modular basis. The functional software system structure and the order of each functional module operation are described in article. The system’s graphical interface structure is discussed separately. An example of calculating and adjusting the safe flight trajectory of an unmanned aerial vehicle is illustrated.