Accident Overview
On August 17, 2020, at approximately 1715 eastern daylight time, a Cessna 150, registration N45083, sustained substantial damage after ditching in a bay near Surry, Maine. The private pilot and passenger were not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Flight and Loss of Power
The pilot reported an uneventful cross-country flight until about 5 miles from the destination airport. During descent into the traffic pattern, the engine sputtered and lost power at an altitude of approximately 1,500 ft above ground level (agl). Despite pumping the throttle and rocking the wings, engine power was not regained. The pilot added 30° of flaps and maneuvered toward a beach. At about 500 ft agl, he observed that the beach was rocky and elected to ditch in shallow water in a bay. The airplane landed in water, and both occupants egressed and swam to shore.
Radar Data and Recovery
Radar data from the Federal Aviation Administration (FAA) tracked the flight from about 5 nautical miles west of the departure airport at 1521, following a direct route toward the destination. Around 1715, the flight track turned toward the eventual accident site, slowing and descending. The last radar hit at 1715:50 showed the airplane at 89 knots groundspeed and 975 ft mean sea level, about 1.5 nautical miles from the site.
First responders buoyed the airplane after the accident, but it subsequently nosed over and became mostly submerged in the saltwater bay. Days later, upon recovery to land, an FAA inspector noted substantial damage to the wings and fuselage.
Postaccident Examination
Engine continuity was confirmed when the propeller was rotated by hand. The ignition switch was found in the BOTH position. Approximately 1 gallon of fuel was drained from the gascolator. The left fuel tank contained no fuel or salt water, while the right tank was about half full with diluted saltwater and an undetermined amount of fuel. The throttle and mixture control levers were full forward, the fuel selector was ON, and the carburetor heat lever was OFF.
Pilot Comments
During a postaccident interview, the pilot stated he had about 3 hours of fuel on board and estimated the flight duration at 2 hours and 10 minutes. He recalled the master fuel ON/OFF lever was ON but could not remember whether carburetor heat was applied during descent. He noted that he was not accustomed to using carburetor heat because most of his flight experience was with fuel-injected engines.
Icing Conditions
A review of the FAA carburetor icing probability chart for the temperature and dew point near the accident site indicated conditions conducive for serious icing at glide power. The FAA Pilot’s Handbook of Aeronautical Knowledge explains that carburetor ice forms due to fuel vaporization and reduced air pressure in the venturi, causing a sharp temperature drop. Ice can restrict the fuel-air mixture flow and reduce power, potentially leading to engine stoppage. Conditions favorable for carburetor icing include temperatures below 70°F and relative humidity above 80%, though icing can occur at higher temperatures and lower humidity levels.