What happened
The pilot-in-command, who was also a certified flight instructor, reported that he failed to apply carburetor heat while descending in the aircraft. As a result, the engine lost power completely. To avoid a more severe outcome, the pilot initiated a forced landing into an open field. During the landing roll, the airplane nosed over.
The investigation
An examination of the conditions on the day of the accident revealed that the temperature and dewpoint were consistent with the FAA icing probability charts. These charts indicated a high probability of serious carburetor icing occurring during glide power operations under those specific atmospheric conditions.
Findings
The loss of engine power was directly attributed to carburetor icing. The pilot's decision not to use carburetor heat during the descent allowed ice to accumulate in the carburetor, leading to the power failure. The subsequent nosing over was a consequence of the forced landing attempt.
Safety message
Pilots must monitor weather conditions closely and use carburetor heat as required, even during glide phases, when temperature and dewpoint spreads indicate a risk of serious carburetor icing.