Cessna 150 N7UT accident near Hohenwald, Tennessee

Probable cause

The pilot’s failure to use carburetor heat in conditions conducive to the formation of carburetor ice, which resulted in a partial loss of engine power due to fuel starvation. Contributing to the outcome was her failure to attain a proper touchdown point during the subsequent diversionary landing, which resulted in a runway excursion.

NTSB analysis

The student pilot was on a solo cross-country flight when the accident occurred. She noticed no irregularities during the preflight inspection, engine run-up, or climb out. About 80 nautical miles (nm) into the flight, while operating at 2,500 ft mean sea level, the engine began to run rough. The pilot moved the throttle and mixture to full, but the engine continued to progressively operate rougher with a subsequent decrease in engine rpm. Unable to maintain altitude, the pilot diverted to the nearest airport. While on final approach, the airplane was high and fast, and she did not believe there was enough altitude to complete a 180° turn to bleed off airspeed, so she continued the approach. The airplane landed long down the runway, exited the paved surface, and collided with a fence resulting in substantial damage to the wings and elevator.

Postaccident examination and a test run of the engine did not reveal evidence of any preexisting anomalies or failures that would have prevented normal operation. The recorded temperature and dew point near the accident site were conducive to “serious icing” at cruise engine power settings. The pilot described the troubleshooting tasks she performed while trying to diagnose the reason for the loss of engine power, but did not report using carburetor heat. Based on this information, carburetor ice likely formed during the cruise portion of the flight, which resulted in a partial loss of engine power and a forced landing. During the approach, the pilot was high, fast, and landed long resulting in a runway excursion.

Text from the NTSB. Open the NTSB docket for ERA24LA087 for the full record.