What happened
On November 2, 2003, a Cessna 150D, registration LN-HAS, departed from Trondheim Airport Værnes for a local familiarization flight. The flight was being conducted by an experienced flight instructor and a student pilot to verify the student's proficiency with the club's aircraft. After climbing to approximately 2,000 feet, the crew proceeded to a training area over the Trondheimsfjord near Frosta.
During the execution of airwork maneuvers, the aircraft entered a power-on stall which transitioned into an unintended spin. Radar data from both Air Traffic Control and the Royal Norwegian Air Force tracked the aircraft's movements, showing that the plane entered a spin at 2,100 feet. The aircraft continued to spin for approximately 25 seconds, completing roughly 7 to 9 turns, before impacting the water. There were two fatalities as both occupants remained strapped into their seats upon impact. The wreckage was located on the seabed at a depth of approximately 100 meters nine days later.
The investigation
The Norwegian Safety Investigation Authority (NSIA) examined radar plots, aircraft wreckage, and witness statements. Investigators analyzed the flight path, which showed the aircraft performing maneuvers such as figure-eight patterns before the loss of control. The investigation also included a technical evaluation of the aircraft's aerodynamic characteristics, specifically focusing on stall and spin recovery capabilities. The investigation noted that the aircraft's pitot-static system had a significant position error, which could lead to inaccurate airspeed indications at high angles of attack.
Findings
- The aircraft entered an unintended spin during a power-on stall maneuver.
- The aircraft remained in a continuous spin from the moment of entry until it struck the water.
- The investigation could not establish a definitive reason why the crew was unable to recover the aircraft from the spin before impact.
- The aircraft exhibited a tendency to flick sharply to the right during power-on stalls, a characteristic that may have contributed to the spin entry.