Accident Details
On the day of the accident, an instructional flight was on base leg turning to final approach at a desert airport. The air traffic control tower authorized the flight to perform s-turns for spacing due to another aircraft stopped in position on the runway and starting the takeoff roll. Witnesses observed the aircraft's wings rock steeply right and left before the aircraft dove nose-first to the ground from about 250 feet above ground level.
Aircraft and Personnel
The flight instructor was recently certificated and had been working as an instructor for about one month, with a total of 363 flight hours. The student was on his first fixed-wing aircraft instructional flight, though he had approximately 60 hours of experience in helicopters and held the foreign equivalent of a private pilot certificate.
Weather and Environmental Factors
Witnesses reported that surface wind varies greatly in the area near the accident site. Two witnesses, one located half a block south and another two blocks east of the accident site, reported calm surface wind. A third witness, located two blocks north, reported wind blowing at about 40 knots; she stated that when she arrived at the accident site soon after the accident and exited her car, the wind blew her hat off across the street. Ten minutes later, the wind stopped and became completely still. At the airport, approximately one mile southeast of the accident location, the surface wind remained less than 12 knots from two hours before to about two hours after the accident. Several pilots reported that wind shear is common in the area due to terrain-induced eddies from nearby mountains. The airport did not have a low-level wind shear alert system.
Post-Accident Examination
One witness reported that the engine was 'sputtering,' and another described it as silent. However, at the accident site, the propeller exhibited deep leading edge damage, torsional twisting, and chordwise striations on the front face. No mechanical anomalies were found during the examination.