Narrative:

I was VFR over the top when the engine of the aircraft starting running excessively rough. I immediately called center and explained my situation; and asked for an IFR clearance to land at a nearby airport. In the process of getting the clearance; I declared an emergency. While being vectored for the approach; the engine started to regain power. I noticed VMC conditions to the north and proceeded to the other airport after canceling IFR. My assumption is that carburetor icing was the cause of my engine troubles. The landing at the other airport was accomplished without further incident.

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Original NASA ASRS Text

Title: A C182 developed a rough running engine at 13;500 FT in marginal weather. The pilot declared an emergency with ATC; safely diverted into a VMC airport; landed with normal engine power and assumed carburetor icing was the earlier problem.

Narrative: I was VFR over the top when the engine of the aircraft starting running excessively rough. I immediately called Center and explained my situation; and asked for an IFR clearance to land at a nearby airport. In the process of getting the clearance; I declared an emergency. While being vectored for the approach; the engine started to regain power. I noticed VMC conditions to the north and proceeded to the other airport after canceling IFR. My assumption is that carburetor icing was the cause of my engine troubles. The landing at the other airport was accomplished without further incident.

Data retrieved from NASA's ASRS site as of April 2012 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.