NTSB Identification: SEA05FA023.
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Accident occurred Saturday, December 04, 2004 in Belgrade, MT
Probable Cause Approval Date: 09/13/2005
Aircraft: Cirrus Design Corp. SR22, registration: N1159C
Injuries: 3 Fatal,1 Serious.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The airplane, flown by a commercial pilot and carrying three passengers, departed in day visual meteorological conditions for a local flight over rugged mountainous terrain. The purpose of the flight was to meet up with a motor glider and make some "flybys" of the glider. The glider pilot was giving a ride to the airplane pilot's friend. The glider pilot reported that the airplane made two passes by the glider. When the airplane passed by the glider for the second time, it was "in coordinated flight," with the flaps up, and it was either flying level or descending slightly. At the time, the glider was at an altitude of about 8,900 feet and had a ground speed of about 57 knots. The glider pilot lost sight of the airplane as it proceeded north into a cirque or bowl formed by a mountain range (peak elevation about 9,600 feet) running north to south and a transverse range (peak elevation 8,916 feet) running west and then hooking south. The glider pilot and passenger did not witness the accident. However, the glider did enter the bowl about 90 seconds after the airplane had passed the glider. The glider pilot executed a left 180 degree turn in the bowl. During the turn, the glider was at altitudes of 9,100 to 9,200 feet and encountered an air mass that was sinking about 100 to 200 feet per minute. The surviving passenger, who was seated in the left rear seat, reported that as the airplane made the second pass on the glider, the stall warning indicator sounded. The pilot dropped the nose to level out, and the stall warning indicator stopped sounding. The passenger heard a high-pitched whine that sounded like a noise he had heard during the preflight check. He thought it was the sound of the flap motor, but when he looked out, he saw that the flaps were not moving. He could not see the pilot moving the flap control, and neither the pilot, nor the other passengers made any comments about the flaps. The pilot then initiated a descending left turn. During this turn, the pilot looked over his shoulder and, in a normal tone of voice, said, "hang on, we might get a couple of trees on this one." It was about 10 to 15 seconds from the time the stall warning horn stopped sounding until they hit the trees. Distribution of the wreckage at the accident site indicated the airplane impacted trees on the transverse ridge at an elevation of 8,553 feet on a southwesterly heading and traveled about 360 feet before coming to rest. Examination of the airframe and engine revealed no evidence of any discrepancies that would have prevented normal operation of the airplane. The flaps were found in the retracted position. Functional testing of the flaps was precluded by impact and fire damage. The pilot who flew the airplane just prior to the accident flight stated that she experienced no problems with the airplane and that the flaps worked normally during her flight. When interviewed 11 days after the accident, the surviving passenger reported that there were no problems with the airplane during the runup or takeoff. About 8 weeks after the accident, he told his attorney that he recalled that the pilot mentioned before takeoff that the flaps were not working.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's failure to maintain altitude/clearance while maneuvering in mountainous terrain, which resulted in an inflight collision with trees and terrain. Contributing factors were the mountainous terrain and the downdraft. Full narrative available
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