NTSB Identification: LAX99FA266.
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Accident occurred Tuesday, August 10, 1999 in BOULDER CITY, NV
Probable Cause Approval Date: 04/06/2001
Aircraft: Cessna 177, registration: N29437
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 purpose of the flight was to provide airplane familiarization to the pilot who had recently purchased the airplane. Winds were from the southeast at 20 knots gusting to 25 knots. The CFI flew with the owner's son an hour prior to the accident with no discrepancies noted with the airframe or powerplant. On their flight, the CFI had the son do a simulated engine-out procedure in the box canyon where the accident subsequently occurred; the flight profile was similar to the one described by witnesses for the accident sequence. The son terminated the procedure and informed the CFI that he was uncomfortable with being so low over the canyon. A witness to the accident saw the airplane turn into the box canyon flush with the top of a bluff, approximately 100 feet above the canyon floor, and then make a tight left turn; the turn was followed by a dust cloud from the impact. He did not hear a sound change or sputtering from the engine, and described the engine as producing power. Emergency response personnel who flew to the accident site within an hour of the crash reported encountering swirling, turbulent winds as they descended below the canyon rim that made their approach into the box canyon very difficult. After obtaining witness statements, the flight crew flew the described flight path. They noted that as they initiated and subsequently completed the turn, the helicopter was pushed by the winds down and towards the accident site. The airframe and powerplant were inspected with no discrepancies noted.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The flight instructor's inadequate supervision of the flight and his failure to maintain an adequate airspeed and altitude margin while conducting low altitude maneuvers in an area of strong gusty winds and terrain-induced turbulence likely to contain wind shear conditions. Full narrative available
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