Accident Summary
A pilot reported that while flying at an altitude of approximately 1,300 feet for about 1.5 hours, he encountered snow flurries. Shortly thereafter, the engine began to vibrate and the RPM dropped. Despite the application of carburetor heat, the condition continued to worsen.
Pilot Actions
The pilot elected to perform a 180-degree turn toward an airport located about 10 miles from his position. However, the airplane was unable to maintain altitude, and the pilot executed a forced landing in a field.
Examination Findings
Post-accident examination of the airplane did not reveal any pre-impact mechanical malfunctions. However, it was noted that the spark plugs were heavily sooted.
Weather Conditions
The weather reported at an airport approximately 29 miles north of the accident site included visibility of 2.5 miles with light snow and mist, scattered clouds at 800 feet, a broken ceiling at 2,200 feet, and temperature and dew point of 31°F and 28°F, respectively.
Carburetor Icing Probability
Review of a carburetor icing probability chart placed the reported temperature and dew point in the range indicating moderate icing at cruise power or serious icing at glide power.