Primary finding
Probable cause
the pilot's inadequate compensation for wind conditions, and his failure to maintain directional control of the airplane, which resulted in a ground swerve and overload failure of the right main landing gear. Factors related to the accident were: the crosswind, and sudden windshift.
Investigator assessment
Analysis narrative
The pilot was departing to the west from a remote airport in a tail-wheel equipped airplane. He reported that initially, there was a left quartering wind (about 25 degrees left of the runway heading) at about 25 knots. During the takeoff roll, the pilot held the airplane on the ground for about 1,100 feet and attained an airspeed of 70 MPH. He indicated the airplane suddenly veered off the left side of the runway. The right main landing gear collapsed, and the right wing struck the ground. After the accident, the pilot noticed the wind was blowing from the north at an estimated velocity of 25 knots. The Facility Directory for the airport included a caution for strong winds, severe turbulence, and possible wind shear.
Source record
Factual narrative
On August 23, 1997, about 1800 Alaska daylight time, a wheel equipped Cessna 170A airplane, N9540A, crashed during takeoff at the Pedro Bay Airport, about 24 miles east of Iliamna, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight, when the accident occurred. The airplane, operated by the pilot, sustained substantial damage. The certificated private pilot, and the sole passenger, were not injured. Visual meteorological conditions prevailed. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on August 23, 1997, at 1245, the pilot reported he was departing runway 27. He indicated a left quartering wind was present and was estimated at 25 knots. The wind direction was oriented about 25 degrees to the left of the departure runway. During the departure takeoff roll, the pilot held the airplane on the ground for about 1,100 feet and attained an airspeed of 70 MPH. The pilot indicated the airplane suddenly veered off the left side of the runway. He described the sudden change in direction of the airplane as wind shear. The right main landing gear collapsed and the right wing struck the ground. After the accident, the pilot noticed the wind was blowing from the north at an estimated velocity of 25 knots. The Alaska Supplement/Facility Directory listing for the airport states, in part: "High mountainous terrain north of the airport. Ten foot pits south of the runway near the apron. Strong winds create severe turbulence and possible wind shear at the airport." -