Incident Overview
On September 13, 2022, at approximately 1132 eastern daylight time, a Cessna 172, registration N388TC, sustained substantial damage when it impacted uneven terrain near Chattanooga, Tennessee. The airline transport pilot and passenger were not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Sequence of Events
According to the pilot, during a previous off-airport landing on an unimproved surface, the right tire struck an object and began losing air pressure. The pilot chose to land at Lovell Field Airport (CHA) in Chattanooga. He declared an emergency with air traffic control and intended to make multiple low passes over a grass area adjacent to runway 20 to assess the best touchdown point. After two low passes, he initiated a go-around. During the subsequent climbout, at an altitude of about 350 feet above ground level and an airspeed of 65 mph, the engine lost power. Power was briefly restored and then lost again. The airplane then struck uneven terrain outside the airport boundary fence.
Damage and Examination
A Federal Aviation Administration inspector examined the airplane and noted substantial damage to the wings and forward fuselage. Fuel was drained from the wings: 7 gallons from the left wing, half a gallon from the right wing. The carburetor contained 5 ounces of fuel. All drained fuel was free of contaminants. A postaccident examination and engine test run revealed no anomalies consistent with a preimpact failure or malfunction.
Carburetor Icing Conditions
According to the carburetor ice probability chart, atmospheric conditions at the time of the accident were conducive to serious icing at glide power. The FAA Special Airworthiness Information Bulletin (CE-09-35) on carburetor icing prevention states that carburetor icing can occur at temperatures above freezing when visible moisture or high humidity is present. The bulletin explains that vaporization of fuel and the Venturi effect cause sudden cooling, potentially leading to ice formation. Carburetor ice may be detected by a drop in rpm in fixed-pitch propeller airplanes and a drop in manifold pressure in constant-speed propeller airplanes, often accompanied by engine roughness.