Dubois, WY, USA
N945RH
PIPER PA-28-140
The pilot was following a highway to the northwest at 10,000 feet mean sea level. He crossed the mountain pass between 700 and 1,000 feet above ground level climbing slowly. Once on the west side of the pass, approaching the base of some cliffs, they encountered a strong down draft and the airspeed dropped rapidly and the airplane started to descend. The pilot reports that he attempted to keep the airspeed at 85 knots and climb but, that the airplane continued to lose altitude. He checked the engine instruments and did not note any degradation of engine performance. The airplane continued to descend. The pilot executed a forced landing in approximately the center of the valley ahead of them. The pilot reported that there were no preimpact mechanical malfunctions or failures. Based on the temperature and pressure readings from the closest weather reporting station, the density altitude at the accident site was about 9,200 feet.
**Modified on July 2, 2009** On April 13, 2008, at 1510 mountain daylight time, a Piper PA-28-140, N945RH, collided with mountainous terrain 26 miles northwest of Dubois, Wyoming. The private pilot operated the airplane under the provisions of Title 14 Code of Federal Regulations, Part 91. The pilot and passenger received minor injuries, and the airplane was substantially damaged. Visual meteorological conditions prevailed, and a VFR flight plan had been filed. The flight originated at Douglas, Wyoming, at 1300. The pilot reported that he was following Highway 287 to the northwest at 10,000 feet mean sea level (msl). He crossed the Togwatee Pass between 700 and 1,000 feet above ground level (agl), and climbing slowly. Once on the west side of the pass, approaching the base of some cliffs, they encountered a strong down draft and the air speed dropped rapidly and the airplane started to descend. The pilot attempted to keep the airspeed at 85 knots and climb but the airplane continued to lose altitude. He checked the engine instruments and did not note any degradation of engine performance. The airplane continued to descend. The pilot executed a forced landing in approximately the center of the valley ahead of them. The pilot and his passenger broke out a window and egressed the airplane. They hiked to the top of the nearest ridge and called for assistance using a cell phone. The nearest automatic weather observation facility was Jackson Hole Airport, Jackson, Wyoming, which is located 39 miles southwest of the accident location. At 1457, the winds at Jackson Hole were 170 degrees at 18 knots.
The pilot's encounter with a windshear/downdraft that exceeded the climb performance capabilities of the airplane.
Source: NTSB Aviation Accident Database
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