Cessna 172N N6360D accident near El Cajon, California

Probable cause

The loss of engine power due to carburetor ice resulting from the flight instructor's failure to use the carburetor heat when simulating an engine failure. Contributing to the accident were the carburetor icing weather condition and the lack of suitable terrain for the forced landing.

NTSB analysis

During a dual instructional flight, while over a reservoir, the certified flight instructor (CFI) simulated an engine failure by retarding the throttle. After about 1 minute of procedures at idle, the CFI applied power, but the engine did not respond. The CFI performed a forced landing to a field on a ranch. During landing, the left wing tip struck the ground, and the left wing sustained structural damage. The engine operated normally during a post accident test run. The temperature and dew point at the nearest reporting point about 6 nautical miles from the accident site near the time of the accident were recorded as 75 degrees Fahrenheit and 55 degrees Fahrenheit, respectively. Plotting these values on a carburetor icing probability chart indicated that the airplane was operating in the range for serious icing at glide power. According to the operator, the CFI did not apply carburetor heat prior to retarding the throttle during the simulated engine failure.

Text from the NTSB. Open the NTSB docket for LAX08LA206 for the full record.