A cooperative engagement group-position determining system employs a group of at least three cooperative units, for example a group of unmanned aerial vehicles (UAV's), with each unit including a GPS system for determining a GPS-based position, an inter-distance measurement module for measuring a distance of the unit relative to at least one other unit, and a computer having a computer-readable storage medium encoded with a program algorithm for correcting the GPS-based position based on at least one relative distance between two units, providing an improved GPS-based position for the unit and for the group. The system can also include a ground controller, for example, for providing flight control for UAV's.