American AA-1 N5796L accident near Llano, Texas

Probable cause

The flight instructor’s delayed remedial action and inadequate supervision during practice traffic pattern work. Contributing to the accident was the flight instructor’s use of sedating medication on the day of the accident and airplane’s high angle of attack at a low altitude during the traffic pattern turn, which prevented recovery during an aerodynamic stall.

NTSB analysis

The flight instructor and student pilot departed for an instructional flight to perform traffic pattern work. A witness saw the airplane on the downwind leg of the traffic pattern and thought the airplane was operating at a very high angle-of-attack. He observed the airplane again a few minutes later, in the same location and operating in the same manner. A helicopter pilot reported that he saw a “flash” of an airplane wing, and then the accident airplane quickly departed controlled flight and descended to the ground. The airplane wreckage was located about 1 mile southeast of the airport. The examination of the engine and airframe did not reveal any additional abnormalities that would have precluded normal operation.

A review of the student pilot’s logbook revealed that he had a total of 14.7 flight hours, including 12.5 hours in the accident airplane. His logbook’s last five entries were annotated as patterns and touch-and-go takeoffs; there was no record of any stall or spin avoidance training noted in his logbook.

The airplane’s stall warning switch, located in the wing, did not indicate any electrical continuity when activated; a small amount of corrosion was observed under the terminal ends of the wires and the wire contact area. The wiring and screws were reassembled and the test was repeated; when activated, electrical continuity was noticed on the meter. The student pilot (who was the airplane owner) had told family members that the stall warning switch was not working properly, so the flight instructor would disable it for each flight. However, even with the stall switch disabled, the instructor should have noticed that the airplane was operating at low speed and high angle of attack yet he did not take corrective action. Based on the circumstances surrounding the accident, it is likely that the student pilot stalled the airplane while performing a high angle-of-attack turn to the downwind leg in the traffic pattern. The airplane’s low altitude would not have provided the pilots with sufficient time or altitude to recover.

Additionally, toxicological testing on the flight instructor detected an antihistamine that is commonly used as a sleep aid in the liver and blood at a potentially impairing level; the antihistamine has potential side effects including cognitive and psychomotor impairment. It is likely that the flight instructor’s use of the sedating medication contributed to his failure to take remedial action when the student flew the airplane at such a high angle of attack at a low altitude.

Text from the NTSB. Open the NTSB docket for CEN12FA570 for the full record.