Piper PA-24-180 N7352P accident near Chugiak, Alaska

Probable cause

The flight instructor's inadequate supervision of the pilot during a simulated loss of engine power, and the pilot's failure to use carburetor heat while operating at a reduced engine power while in carburetor icing conditions.

NTSB analysis

The certificated flight instructor (CFI) was administering a biennial flight review to the private pilot/airplane owner whose previous biennial review had expired. The CFI said that while in level flight at 1,600 feet msl, as the airplane approached the accident airport, he closed the engine throttle, and told the pilot that he was simulating an engine failure, then instructed the pilot to make an emergency descent and landing at the airport ahead. During the simulated emergency descent, the CFI momentarily advanced the engine throttle to ensure engine power was still available, and the engine appeared to respond accordingly. As the approach progressed, the pilot lowered the landing gear, and the airplane's descent rate increased significantly. The CFI instructed the pilot to go-around when he realized that the airplane was too low on the approach. The pilot immediately applied full engine throttle, but the engine did not respond, and he selected an area of grass-covered terrain as a forced landing site. During the forced landing the airplane struck a perimeter fence, and the nose and main landing gear collapsed. The airplane sustained substantial damage to the fuselage and wings. An NTSB postaccident inspection disclosed no evidence any preimpact mechanical problems. An aviation weather reporting station indicated that the temperature was 54 degrees F, and the dew point was 32 degrees F. When these values are entered into a carburetor icing probability chart, the results are in the "Serious icing-glide power" category. Both pilots reported that carburetor heat was not used during the simulated emergency descent and approach. A pilot that landed about 15 minutes after the accident reported that while on approach, his airplane's engine developed carburetor ice, which required the use of carburetor heat. Given the lack of any mechanical anomalies it is likely that the formation of carburetor ice resulted in the loss of engine power.

Text from the NTSB. Open the NTSB docket for ANC09LA036 for the full record.