Incident Overview
A commercial pilot and a passenger were conducting a pipeline patrol aerial observation flight. While maneuvering at 700 feet above mean sea level, the aircraft's engine began running roughly. The pilot responded by applying full carburetor heat and initiating a turn toward an open field, intending to carry out a precautionary landing. However, the engine then stopped running, and the pilot was forced to establish an emergency descent to an open pasture.
Forced Landing and Impact
During the emergency descent, the airplane was unable to clear a line of trees 20 to 30 feet in height that bordered the pasture. The aircraft struck the trees, and the forced landing concluded with the airplane sustaining substantial damage.
Investigation Findings
In a post-accident interview with an FAA inspector, the pilot stated that he normally flew with the carburetor heat partially open. The investigation determined that the pilot's improper use of carburetor heat induced the formation of carburetor ice, which caused the loss of engine power. This improper management of the carburetor heat setting led to ice accumulation in the carburetor, ultimately resulting in the engine failure.