This article addresses the problem of optimal flight path planning when surveying the field using several unmanned aerial vehicles (UAVs). The trajectories of the drones are configured in order to minimize the time of the sub-areas coverage (assigned to each drone in the group), provided that the whole field is completely covered. The algorithm consists of four stages: converting the coordinates of a given field into Cartesian (metric system); splitting the field into sub-areas assigned to be covered by each drone in the group; forming the flight trajectory (plan) for each drone; and iterative minimization of the maximum time needed to cover the assigned sub-areas. The algorithm for optimal flight path planning is more time-effective than the ones where the drone moves straight from one end of the field to the other with shifts (moving along the boundary of the field at a certain distance). To implement the developed, an additional software module of the virtual simulator has been developed. The workability and the adequacy of the proposed algorithm were experimentally confirmed using a three-dimensional model of a real agriculture field in the virtual simulator.