Incident Overview
During a visual flight rules (VFR) flight, the pilot reported that the engine began to run roughly between 30 minutes and 1 hour after departure. The pilot responded by applying carburetor heat, but the engine roughness worsened, prompting him to turn the carburetor heat off after approximately one minute. Subsequently, the pilot decided to take emergency action and executed a forced landing to the top of a nearby mountain.
Weather Conditions
Weather conditions reported about 17 nautical miles west of the accident site—located between the accident site and the destination airport—were well below the minimums for VFR flight. When asked about the weather during the flight, the pilot stated that visibility was at least 1 mile and that he stayed clear of clouds, noting that he was operating in Class G airspace.
Carburetor Icing Considerations
Interpolation of a carburetor icing probability chart indicated that atmospheric conditions were conducive to moderate icing at cruise power or serious icing at glide power. An FAA publication provides pilots with warning signs of carburetor icing, including a loss of engine revolutions per minute (RPM) in airplanes equipped with a fixed-pitch propeller. The publication recommends that pilots apply full carburetor heat immediately when carburetor icing is suspected, noting that the engine may run rough initially for a short time while ice melts.
Response and Outcome
The pilot's actions—turning off carburetor heat after a brief application—contrasted with the FAA publication's guidance to maintain full heat until ice clears. The forced landing resulted in the aircraft coming to rest on the mountain top. No further details about injuries, aircraft damage, or subsequent events are provided in the source.