What happened
While the aircraft was en route, the pilot noticed that he had lost his airspeed indication. Observing the pitot head on the wing with a flashlight, he stated that the flip-up cover was down, covering the ram tube. Unable to maintain proper airspeed, the pilot inadvertently achieved an excessive rate of sink, impacting a steep slope at the approach end of the runway.
The investigation
The investigation determined that the pitot head was obstructed by its protective cover. This obstruction prevented accurate airspeed data from reaching the instrument, leaving the pilot without critical flight information during a critical phase of flight.
Findings
The primary factor contributing to this accident was the failure to remove the pitot tube cover before flight. This oversight led to a loss of airspeed indication, which prevented the pilot from maintaining controlled flight and resulted in a collision with terrain.