Primary finding
Probable cause
The first pilot's failure to maintain clearance with a tree. Factors in the accident were the first pilot's inadequate preflight planning and preparation and soft snow conditions.
Investigator assessment
Analysis narrative
The certificated private pilot (first pilot), occupying the left seat, and a certificated airline transport pilot/flight instructor (second pilot), occupying the right seat, were departing a remote airstrip that was a 1,400 feet long area of compacted snow. The surface of the snow was soft and rough. By mutual agreement, the first pilot agreed to maintain directional control of the airplane during the takeoff roll. The second pilot agreed to manipulate the flaps to shorten the airplane's takeoff roll. During the takeoff roll, both pilots were focused in front of the airplane, and the left wing struck a tree, damaging the wing spar. The second pilot reported that the wind was from the east about 10 knots. The temperature was about 40 degrees F and the takeoff area sloped uphill about 1.5 degrees.
Source record
Factual narrative
On April 17, 1996, about 1400 Alaska daylight time, a wheel/ski equipped Cessna 170B, N39781, collided with a spruce tree during takeoff from a remote area, about 23 miles west of Chicken, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight when the accident occurred. The airplane, registered to the first pilot, sustained substantial damage. The certificated private pilot (first pilot), occupying the left seat, and a certificated airline transport pilot/flight instructor (second pilot), occupying the right seat, were not injured. Visual meteorological conditions prevailed. The first pilot reported that he had established a 1,400 feet long area of compacted snow to support his mining operation in the area of Gold Creek. He was planning to fly the second pilot to Chicken, Alaska. The takeoff area is located at 3,700 feet mean sea level and is oriented in a northeast/southwest direction. The surface of the snow was soft and rough. The first pilot indicated that by mutual agreement, he would maintain directional control of the airplane during the takeoff roll. The second pilot would manipulate the flaps to shorten the airplane's takeoff roll. During the takeoff roll to the northeast, the first pilot reported that both pilots were focused in front of the airplane, but the left wing struck a tree, damaging the wing spar. The second pilot reported that the wind was from the east about 10 knots. The temperature was about 40 degrees F and the takeoff area sloped uphill about 1.5 degrees. -