Witness Observations
The airplane departed from a private airstrip for a short flight between two airstrips located less than 1 mile apart on opposite sides of a river in rugged mountainous terrain. A witness at the departure airstrip reported an uneventful takeoff. A witness at the destination airstrip heard the airplane fly overhead heading downstream and stated that was the pilot's routine before landing.
Witnesses river rafting less than 1 mile downstream of the destination airstrip observed the airplane fly over them heading downstream at an altitude of about 150 feet above ground level. They reported that the airplane then entered a steep left turn, completed approximately 180 degrees of turn, collided with a tree, and impacted rocky terrain on the river bank.
Mechanical Examination
Examination of the airframe and engine revealed no evidence of any discrepancies that would have prevented normal operation of the airplane.
Pilot Information
The pilot had a history of allergies. Toxicological testing detected brompheniramine, a sedating antihistamine available over the counter, in the pilot's blood at .223 ug/ml. The pilot also had a severe color vision deficiency.
Environmental Conditions
At the time of the accident, skies were clear, and the sun was in the east at an altitude of 34.3 degrees above the horizon. As the pilot turned the airplane left from a downstream (southerly) heading to an upstream (northerly) heading, he would have been heading east directly toward the rising sun approximately midway through the turn.