NTSB Identification: LAX07FA241.
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Accident occurred Sunday, August 05, 2007 in S. Lake Tahoe, CA
Probable Cause Approval Date: 04/30/2008
Aircraft: Piper PA-28-140, registration: N8938C
Injuries: 1 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 single engine airplane appeared to be returning to the airport shortly after takeoff when witnesses saw it descend into trees. The pilot radioed his intentions to perform a downwind departure from runway 18. Approximately 3 minutes later, the pilot made his final radio transmission, stating that he was turning left crosswind. Witnesses reported seeing the airplane in a right turn about 20 feet above the treetops, with a slightly nose low attitude. The airplane then rolled to a level attitude, heading in a northerly direction, and started to descend just prior to its collision with trees. Witnesses also reported hearing the engine at what they described as a high power setting initially, then it dropped to a lower sounding power setting just before the airplane contacted the trees. Postaccident inspection of the airframe and engine revealed no evidence of a mechanical failure or malfunction. The airport is located in a mountain valley with rising terrain immediately to the west, south, and east, and a lake to the north. The elevation is 6,264 feet. The winds were from the south at 16 knots gusting to 31. The density altitude was calculated to be 8,445 feet. Using the airplane's pilot operating handbook (POH) performance charts, the pilot could expect the airplane to be able to maintain a 220 foot per minute rate of climb at 89 miles per hour for this density altitude. The POH published stall speed for zero angle of bank and zero flaps is 55 miles per hour. Advisory Circular AC 00-57 states, "Aircraft that engage in low-level flight operations over mountainous terrain in the presence of strong winds (20 kt or greater at ridge level) can expect to encounter moderate or greater turbulence, strong up-and-downdrafts, and very strong rotor and shear zones." Information available at the airport states that downdrafts are often encountered near the runway abeam the terminal building and west of the golf course, which is along the crosswind and downwind routes for runway 18 departures. The pilot probably encountered turbulence and downdrafts, a reduced rate of climb, and rising terrain to his left shortly after takeoff. It is likely he elected to return to the airport for landing, but was unable to maintain altitude during the turn due to the turbulence/downdrafts, and collided with trees.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's inadequate preflight planning/decision, and his failure to maintain clearance from trees during takeoff-initial climb. Contributing to the accident were turbulence, downdrafts, and rising terrain. Full narrative available
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