American AA-1 N5909L accident near Truckee, California

Probable cause

The pilot's failure to lean the fuel mixture during takeoff in high-density altitude conditions, which resulted in a loss of engine power.

NTSB analysis

The private pilot was conducting a ferry flight for the airplane's owner. The pilot reported that, before takeoff, he leaned the fuel mixture for taxi but that, on takeoff, the mixture was full rich. During the initial climb, the engine lost power; the pilot stated that he did not remember anything after the loss of power occurred. The airplane subsequently collided with trees about 8 miles east of the airport, which is at an elevation of 5,901 ft and surrounded by mountainous terrain. Postaccident examination of the airframe and engine revealed no mechanical anomalies that would have precluded normal operation.

According to the airplane owner's manual, during takeoff or climb from high-altitude airports, the engine should be leaned to achieve maximum rpm; the calculated density altitude at the time of the accident was about 6,552 ft. The manual further stated that, at full throttle climb at altitudes above 5,000 ft, the fuel mixture should be leaned for smooth engine operation. The manual noted that a rough-running engine can result from an improper fuel/air mixture.

Text from the NTSB. Open the NTSB docket for WPR13LA251 for the full record.