NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
As the airplane neared the destination airport in dark night visual meteorological conditions at the conclusion of a cross-country flight, the private pilot reported a partial loss of engine power. The air traffic controller provided the pilot with a vector and information for the nearest airport, which, according to his display, was equipped with a lighted, grass runway. Although the airport was equipped with a rotating beacon and runway lighting, these lights could not be pilot-operated and required manual activation by the airport owner. This information was not available to the controller. In attempting to assist the pilot in restoring engine power, the pilot-rated controller suggested that the pilot turn off the carburetor heat. Eventually, radar contact with the airplane was lost, and the controller continued to provide vectors to the pilot while also attempting to obtain more information about the airport, including a common traffic advisory frequency to activate the lighting system. Radio contact was lost with the airplane about 7 minutes after the loss of radar contact.The airplane impacted trees and terrain about 1 nautical mile from the diversionary airport. All of the engine’s spark plugs displayed carbon fouling, consistent with an overly rich fuel-air mixture. No other anomalies were detected with the airframe or engine that would have precluded normal operation. Although the airplane was operating in an area conducive to the formation of carburetor icing at glide power, it could not be determined if the engine experienced carburetor icing at the time the pilot reported that she had engine problems because she had the carburetor heat on and was likely operating at cruise power. Additionally, the effect of the controller’s suggestion to turn off the carburetor heat could not be determined.