What happened
On 14 January 2020, a Cessna 150-M, registration EC-CVP, was conducting a dual-command training flight from Cuatro Vientos Airport when the crew experienced a significant loss of engine power. While cruising at 3,500 ft, the engine revolutions dropped from 2,300 to approximately 2,100 rpm. In response, the instructor took control and activated the carburetor heat to mitigate potential icing.
As the aircraft continued toward Aldea del Fresno, a second power loss occurred, with revolutions dropping further to 1,500 rpm, making it impossible to maintain altitude. The pilot transitioned to a glide at 55/6/0 kt and identified a suitable labor field in the municipality of Villamanta for an emergency landing. To maximize available power for the final approach, the pilot deactivated the carburetor heat.
Upon touchdown, the aircraft bounced, making a second impact that caused the nose gear to collapse. The aircraft subsequently traveled several meters before flipping onto its back. The instructor escaped uninjured, but the student sustained one serious injury.
The investigation
The CIAIAC examined the engine, the wreckage, and the meteorological conditions at the time of the accident. An inspection of the engine and magnetos revealed no mechanical anomalies or failures in the fuel system. The investigation focused on the atmospheric conditions, noting that the ambient temperature was approximately 2°C with high relative humidity (around 90-95%), which are conditions highly conducive to carburetor icing.
Investigators also analyzed the landing technique, determining that the aircraft's second impact was unstable due to an incorrect pitch attitude and excessive speed, which caused the bounce and subsequent nose gear collapse.
Findings
- The primary cause of the accident was the performance of an emergency off-airfield landing following an in-flight engine power loss.
- Carburetor ice formation is considered the likely cause of the power loss, as the aircraft was operating in a flight regime characterized by high humidity and temperatures near freezing.
- A contributing factor was the pilot's decision to deactivate the carburetor heat during the final approach to gain power, which prevented the melting of any existing ice.
- Inadequate flight preparation regarding the specific icing risks posed by the day's meteorological conditions also contributed to the event.