Narrative:

[I performed a] precautionary landing in a cow pasture after experiencing a rough running engine. [I] checked the fuel for water after landing and for carburetor ice as requested by a local mechanic. [I] found the fuel selector switch positioned between both and right tank. [I am] not sure if this was done during the emergency check or before landing; since all was so quick because of patrol altitude of around 400 ft. [Note that] we have waivers to fly as low as 200 ft. [I] test ran the engine on the ground several minutes with no problems before taking off. [I then] landed at the nearest airport and topped off the fuel. The aircraft still had 10 plus gallons of fuel on board or over one hour of fuel at 8 gallon per hour burn. No damage to aircraft or property.

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Original NASA ASRS Text

Title: The pilot of a C172 performing pipeline inspections experienced a rough running engine and elected to land in a field. He later found that the fuel selector was in a position between both and right; but was unsure how this occurred. He ran up the engine and took off successfully.

Narrative: [I performed a] precautionary landing in a cow pasture after experiencing a rough running engine. [I] checked the fuel for water after landing and for carburetor ice as requested by a Local Mechanic. [I] found the fuel selector switch positioned between both and right tank. [I am] not sure if this was done during the emergency check or before landing; since all was so quick because of patrol altitude of around 400 FT. [Note that] we have waivers to fly as low as 200 FT. [I] test ran the engine on the ground several minutes with no problems before taking off. [I then] landed at the nearest airport and topped off the fuel. The aircraft still had 10 plus gallons of fuel on board or over one hour of fuel at 8 gallon per hour burn. No damage to aircraft or property.

Data retrieved from NASA's ASRS site as of July 2013 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.