Flight History
A non-instrument-rated private pilot departed after a delay and was in a hurry to return home. He elected to fly over mountainous terrain in dark, nighttime conditions. Recorded radar data indicate that after approximately two hours of cruising, the airplane began a slow descent from 12,600 to 11,100 feet mean sea level.
Accident Sequence
The radar track then showed the airplane commencing a clockwise turn while continuing to descend. While reversing course, the pilot became spatially disoriented, and the airplane rapidly descended, as evidenced by its sudden disappearance from radar. During the descent, the airplane broke apart.
Wreckage Examination
Wreckage was located on a 6,400-foot mountain and was scattered over a 950- by 350-foot oval area. Major components that separated included the horizontal stabilator, vertical tail surfaces, and the 6-foot-long outboard span of both wings. The propeller blades exhibited signatures consistent with absorption of rotational energy during ground impact. Examination revealed no preimpact anomalies; all fractures were overload in character.
Conclusions
The descending flight profile, followed by a course reversal away from the destination, was consistent with a spiral maneuver. The structural breakup resulted from aerodynamic forces induced by the pilot's recovery attempts that exceeded the airframe's strength.