What happened
On November 9, 2015, a private Wassmer WA40 A, registration F-BLFP, departed from Propriano aerodrome for a local flight. During the initial climb, at an estimated altitude of 300 feet, the pilot experienced engine misfires and a noticeable drop in engine RPM. In an attempt to restore power, the pilot activated the electric pump several times and checked the magnetos; however, the engine failed to produce sufficient power.
Recognizing the emergency, the pilot initiated a forced landing, turning left toward the coastline and deploying the flaps to the second notch. As the aircraft reached a height of approximately three to four meters just meters from the shoreline, it entered a stall and struck the surface of the sea. The pilot successfully evacuated the aircraft before it sank following the arrival of emergency services. The aircraft sustained heavy damage.
The investigation
The investigation focused on the engine performance and environmental conditions at the time of the accident. The aircraft was within its weight and balance limits, and approximately 50 liters of fuel remained in the tanks. Meteorological data indicated a temperature of 10°C with a dew point of 9°C, resulting in very high humidity (above 85%) and cool air—conditions highly conducive to significant carburetor icing regardless of engine power settings.
While the pilot had performed engine checks, including a carburetor heat efficiency test, prior to takeoff, no anomalies were detected. The pilot noted that they did not anticipate the possibility of icing during the flight preparation. The investigation also considered the mechanics of carburetor icing, noting that if ice remains partially accumulated after ground tests, additional ice can form during the takeoff roll and initial climb.
Findings
- The primary cause of the engine power loss was carburetor icing.
- Atmospheric conditions were highly favorable for heavy icing due to high humidity and cool temperatures.
- The pilot did not anticipate the risk of icing during flight preparation, which prevented proactive measures.
- Residual ice from ground operations may have persisted if the carburetor heat test was not sufficiently long to clear all accumulation, leading to further ice formation during the climb.