Aircraft Accident/Incident Report

Springville, California 93265
Sunday, November 27, 1994 11:15 PST

While on a personal sightseeing flight in the Sierra Nevada Mountains, the aircraft collided with trees at the 8,300-foot level in a box canyon. The floor of the canyon rises steeply from the entrance; about 3,000 feet in 3 miles. The surrounding ridge tops which form the box rise to elevations in excess of 11,000 feet msl. Based on witness and NWS observations along the route of flight, light wind conditions prevailed in and around the accident site with no documented unusual meteorological phenomena. A passenger took videotapes of the accident flight and two previous flights. The parts of the tape with the prior flights showed the aircraft flying extremely low in and out of mountain valleys, along the desert floor, and at wave top level along the beach. The parts of the tape with the accident flight showed the aircraft low flying along the desert floor in a canyon, then buzzing a lake. The remainder of the tape showed the aircraft flying up the river valley which leads to the accident site until it abruptly stops at a damaged portion of the tape. The pilot said he flew up the river valley about 1,800 to 2,000 feet above the river [6,000 to 7,000 feet msl], then turned right at a fork in the river which leads up to the accident site canyon. He said he was at 12,000 feet msl when he turned and was over the surrounding ridges. Nearing the accident site area, the aircraft was suddenly rolled and yawed to the right by very strong turbulence. The pilot said he had the impression that the aircraft was being pushed forward and down towards the ground by some strong force. The aircraft was descending and the pilot said he managed to recover the aircraft to level flight just before colliding with trees.

the pilot's entry into a box canyon at an altitude insufficient to maintain clearance from the surrounding terrain and obstacles. Factors in the accident were the high density altitude condition and the steep, rapidly rising nature of the mountainous terrain.