NTSB Identification: SEA97LA163.
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Accident occurred Saturday, July 05, 1997 in BIG CREEK, ID
Probable Cause Approval Date: 01/28/2000
Aircraft: Piper PA-18-150, registration: N4249Z
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

While circling the Mile Hi United States Forest Service emergency airstrip to look at another aircraft accident, the pilot encountered lee side winds (downdraft), lost altitude and 'wound up having to flare to land.' The pilot intended to coast upslope and southbound over the ridge on which the north/south strip is situated, and take off on the upwind side. When the aircraft reached the top of the ridge the aircraft encountered an upslope wind which yawed the aircraft right. The aircraft then became airborne, crossing the top of the ridge and impacting the left main landing gear which then collapsed. The pilot estimated the winds at the accident site as 130-140 degrees at 5 to 10 knots, and the temperature at 80 degrees Fahrenheit. The approximate density altitude based on that temperature and elevation was 8,700 feet.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot-in-command's inadequate terrain clearance and failure to maintain directional control. Also, the overload of the aircraft's left main landing gear strut assembly. Factors contributing to the accident were high density altitude conditions, downdrafts (associated with the lee side of mountain flying), and crosswinds.

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