Accident Overview
On April 14, 2024, at approximately 2008 eastern daylight time, a Cessna 172C, registration N8337X, was substantially damaged in an accident near Manassas, Virginia. The private pilot was not injured, and the passenger sustained minor injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Flight History
The pilot was en route to the destination airport at an altitude of 5,500 feet mean sea level (msl). According to communications information from the Federal Aviation Administration (FAA), air traffic control instructed the pilot to descend to, but remain at or above, 2,600 ft msl. The pilot reported that he reduced throttle but did not apply carburetor heat at any time during the descent. ADS-B data indicated the airplane began a gradual descent from about 5,500 ft after 1959:09. The pilot was later cleared to descend to 2,000 ft msl. While flying at that altitude with the destination airport in sight, he applied throttle to increase engine power, but the engine did not respond. About 2006, he informed the tower controller that the “motor was unresponsive,” and the controller cleared the airplane to land on runway 16R. The airplane touched down in a grassy area on airport property short of the runway, collided with a drainage culvert, and nosed over, resulting in substantial damage to the vertical stabilizer.
Postaccident Examination
A postaccident examination of the engine by an FAA inspector confirmed continuity of the crankshaft, camshaft, and valvetrain. Thumb suction and compression were noted in all cylinders, though compression was low in two cylinders due to leakage past each intake valve. Examination of the air induction, ignition, exhaust, and fuel metering systems revealed no evidence of preimpact failure or malfunction. Impact damage to the carburetor precluded functional testing of the engine.
Atmospheric Conditions
A High Resolution Rapid Refresh (HRRR) model sounding was created for the approximate time and location where the pilot initiated the descent. At 5,069 ft msl, the temperature and dew point were about 16.8°C and about 0.4°C, respectively, with a relative humidity of 33 percent. At 6,076 ft msl, the temperature and dew point were about 13.7°C and about -0.6°C, respectively, with a relative humidity of 37 percent. Review of the icing probability chart contained within FAA Special Airworthiness Information Bulletin CE-09-35 indicated that the atmospheric conditions at the time of the accident were “conducive to serious icing at glide [idle] power.” FAA Advisory Circular 20-113 and the airplane owner’s manual contain recommendations and checklists regarding carburetor heat usage.