Cessna 172 N6922A accident near Glendora, California

Probable cause

The flight crew's failure to maintain adequate terrain clearance while maneuvering in downdraft conditions over mountains.

NTSB analysis

The flight instructor reported that he and the commercially certificated student flew to mountainous terrain to practice using orographic lift. The flight instructor stated that the lift they were flying in began to dissipate so he took the flight controls and added full power to depart the area. Suddenly, they encountered a strong downdraft and moments later they impacted the terrain. It is likely that the airplane was not at a sufficient altitude for the pilot to recover from the downdraft encounter and clear the terrain. The flight instructor told local authorities at the time of his rescue that there were no problems with the airplane. A postaccident examination revealed no evidence of any preimpact mechanical anomalies with the airframe or engine that would have precluded normal operation.

Text from the NTSB. Open the NTSB docket for WPR11FA117 for the full record.