Sequence of Events
Witnesses observed the aircraft for approximately 8 minutes as it executed erratic diving, climbing, and steep-turning maneuvers. The sequence culminated in a 12° descent to the ground. Throughout the maneuvers, the engine was heard running, and evidence indicated engine power at impact.
Impact and Damage
The aircraft struck trees, a farm building, farm equipment, and a vehicle before bursting into flames. The wreckage was strewn along a 320-foot path. Examination of the wreckage revealed no evidence of flight control malfunction.
Pilot Communications and Condition
Before the flight, the pilot reported an upset stomach. During radio transmissions, the pilot's speech was slurred. The pilot did not respond to the last radio call from Sioux Falls tower. No emergency or distress calls were received from the pilot.
Postmortem Examination
The postmortem examination of the pilot did not identify specific impairment but was limited due to the severity of the impact and fire damage.
Probable Cause Findings
Occurrence #1: In-flight collision with terrain/water during maneuvering. Findings: (1) The pilot performed an improper maneuver. (2) The pilot did not maintain aircraft control. (3) Physical impairment was present. (4) Objects involved included trees, a nonresidential building, and a vehicle.