before powered flights were undertaken, a series of glide flights were conducted. on may 10, 1967, the sixteenth and last glide flight ended in disaster as the vehicle slammed into the lake bed on landing. with test pilot bruce peterson at the controls, the m2-f2 suffered a pilot induced oscillation (pio) as it neared the lake bed. at the core of this problem was the fact that the wings of the m2-f2 (essentially the body of the aircraft) produced considerably less roll authority than most aircraft. this resulted in less force available to the pilot to control the aircraft in roll. as a consequence, when peterson attempted to perform roll maneuvers the response of the vehicle was substantially less than expected, thus lending to a "soft" feel for this control which often leads to pio in the roll axis. the vehicle rolled from side to side in flight as he tried to bring it under control. peterson recovered, but then observed a rescue helicopter that seemed to pose a collision threat. distracted, peterson drifted in a crosswind to an unmarked area of the lake bed where it was very difficult to judge the height over the ground because of a lack of guidance (the markers provided on the lake bed runway).