This paper presents Modified Artificial Potential Field (MAPF) approach application for decentralized formation control of multiple Unmanned Aerial Vehicles (UAVs) flying through dynamic environment. MAPF is based on Formation Potential Field (FPF) and it allows preventing mid-air collisions within defined security zone around multiple UAVs. This technique combines issue resolution connected with oscillation effects produced by potential fields, UAV fixed-wing type specification with the respect to application in the dynamic environment. Based on measured ranges between Remotely Piloted Aircraft (RPA) and obstacles (buildings, restricted areas), attraction and repulsion forces are formulated and are converted to aircraft flight control commands via rudder, aileron trims and engine throttle. The simulation results are used to validate and verify a given approach of real application, provision of optimal, collision-free, and safety flight path between initial UAVs positions and destination area.