Christen Industries Inc A-1 N9609H accident near Twin Falls, Idaho

Probable cause

Partial loss of engine power during a low pass, due to carburetor icing and the pilot’s failure to use carburetor heat during the landing approach.

NTSB analysis

The pilot reported that he was practicing basic flight maneuvers at an altitude of about 3,500 ft agl during a short uneventful local flight. He then reduced engine power to idle and initiated a descent back to the private dirt airstrip with the intention of first performing a low pass to confirm the runway was clear, and then landing. As he flew past the runway, he applied full throttle, but the engine did not respond. He then performed a forced landing into an adjacent wheat field, where the airplane nosed over during the ground roll. The pilot stated that he had not used a checklist during the descent and forgot to apply carburetor heat. The wing lift struts, and the vertical stabilizer were substantially damaged. The pilot reported that there were no mechanical failures or malfunctions with the airplane or engine that would have precluded normal operation.

The carburetor icing chart from FAA Special Airworthiness Information Bulletin CE-09-35 “Carburetor Icing Prevention” indicated a potential for serious icing at glide power for the temperature and dew point depicted at the time of the accident.

Text from the NTSB. Open the NTSB docket for WPR21LA264 for the full record.