This May 2009 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Aircraft: Cessna 150. Injuries: 2 Minor. Location: Baton Rouge, La. Aircraft damage: Substantial.
What reportedly happened: The student pilot and CFI were conducting a cross-country flight at night. Weather conditions were conducive to carburetor icing at both cruise and descent power settings. When the airplane was about seven miles from the first destination, the engine’s performance began to decay. The student suggested that they apply carburetor heat, but instead the CFI elected to turn around and fly approximately 16 miles back to the departure airfield. The engine performance continued to decay. The CFI took command of the airplane and did a forced landing about four miles from the airport. During landing, the airplane flipped over on its back.
The post-accident investigation did not find any mechanical issues with the airplane. The fuel was also free of contaminants.
Probable cause: The partial loss of engine power due to the instructor pilot’s failure to use carburetor heat while operating in conditions conducive to carburetor icing. Contributing to the accident was the instructor pilot’s decision to attempt a return to the departure airport with degraded engine performance.
For more information: NTSB.Gov