The ATV made its first flight on July 28. This flight consisted of three vertical hops totaling 4 min 40 sec in duration and reaching a maximum altitude of 8 ft (2.4 m). The pilots found the flying extremely challenging for a number of reasons. Visibility in the cockpit was so restricted that the pilots nicknamed it the Batcave. The view of the ground was entirely obstructed, so the pilots had to rely on a sonar altimeter to judge ground proximity. The entire craft had a low rotational inertia, and torque from the spinning rotor blades made the body spin, unless counteracted by yaw thrust in the opposite direction.