Narrative:

Departed on an IFR flight plan to our home base with 4 souls on board. Plane was hangared overnight due continuous rain forecast. Tanks were topped off; preflight; fuel samples and run-up all normal. Take-off normal in rain; low visibility and ceiling. Leveled off at 3000 feet then cleared to 7000 feet. All normal until approaching 5000 feet when engine was not developing climb power. Turned on carb heat with no noticeable change. Turned off carb heat after 4-5 min. Turned on electric fuel pump; changed tanks; adjusted mixture with no change. I did not check the magnetos. Was able to hold altitude at this time but little if no climb. Told ATC we had a problem and wanted to return. He replied that the wx had deteriorated at ZZZ and ZZZ1 had better conditions and was closer. I accepted that recommendation and he began vectoring us to the 14 ILS localizer. Shortly before joining the localizer I turned on carb heat again but engine power continued to worsen. Couldn't hold altitude or airspeed; controller advised he didn't show any roads or fields near our position. Broke out at about 400 feet AGL and landed in a farmer's plowed and very muddy field. No injuries and no damage to the plane. No cause has been determined at this time; but I think carb ice could be a likely reason. Perhaps I missed signs and should've turned it on earlier or left it on longer; or perhaps the carb heat didn't work as designed for whatever reason. Also could be fuel or ignition problems but again my feeling is carb ice.

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Original NASA ASRS Text

Title: PA28 pilot reports departing on an IFR flight plan in IMC. Climbing to 7;000 feet power becomes insufficient to continue climbing. Carb heat is tried along with fuel pump and switching tanks without success. ATC is advised and a diversion planned but the aircraft runs out of altitude before reaching the airport and lands in a muddy field.

Narrative: Departed on an IFR flight plan to our home base with 4 souls on board. Plane was hangared overnight due continuous rain forecast. Tanks were topped off; preflight; fuel samples and run-up all normal. Take-off normal in rain; low visibility and ceiling. Leveled off at 3000 feet then cleared to 7000 feet. All normal until approaching 5000 feet when engine was not developing climb power. Turned on carb heat with no noticeable change. Turned off carb heat after 4-5 min. Turned on electric fuel pump; changed tanks; adjusted mixture with no change. I did not check the magnetos. Was able to hold altitude at this time but little if no climb. Told ATC we had a problem and wanted to return. He replied that the wx had deteriorated at ZZZ and ZZZ1 had better conditions and was closer. I accepted that recommendation and he began vectoring us to the 14 ILS localizer. Shortly before joining the localizer I turned on carb heat again but engine power continued to worsen. Couldn't hold altitude or airspeed; controller advised he didn't show any roads or fields near our position. Broke out at about 400 feet AGL and landed in a farmer's plowed and very muddy field. No injuries and no damage to the plane. No cause has been determined at this time; but I think carb ice could be a likely reason. Perhaps I missed signs and should've turned it on earlier or left it on longer; or perhaps the carb heat didn't work as designed for whatever reason. Also could be fuel or ignition problems but again my feeling is carb ice.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.