What happened
The Cessna aircraft departed for a short flight between two private airstrips located less than one mile apart on opposite sides of a river in rugged mountainous terrain. A witness at the departure site reported that the takeoff was uneventful. Upon reaching the destination airstrip, witnesses observed the aircraft flying downstream, which was described as part of the pilot's routine before landing.
While river rafting less than one mile downstream from the destination airstrip, witnesses observed the airplane fly over at an altitude of approximately 150 feet AGL. During this maneuver, the aircraft entered a steep left turn and completed approximately 180 degrees of the turn before colliding with a tree. The aircraft then impacted rocky terrain on the river bank. There were no fatalities reported in the accident.
The investigation
Examination of the airframe and engine revealed no evidence of any discrepancies that would have prevented normal operation of the aircraft. Environmental conditions at the time of the accident included clear skies, with the sun positioned in the east at an altitude of 34.3 degrees above the horizon. As the pilot transitioned from a southerly heading to a northerly heading during the left turn, the aircraft would have been heading directly toward the rising sun midway through the maneuver.
Findings
Toxicological testing of the pilot's blood detected brompheniramine, a sedating antihistamine available over the counter, at a concentration of .223 ug/ml. Additionally, the pilot had a history of severe color vision deficiency.