What happened
On June 26, 2011, a Siren PIK 30 motor glider, registered F-CFPO, was performing a local flight from the Itxassou aerodrome. During the takeoff roll on runway 26, the pilot attempted an acceleration phase at a very low altitude, maintaining a level flight path approximately one meter above the unpaved surface.
As the aircraft reached a speed of approximately 90 km/h, the pilot experienced a sudden loss of lift due to wind effects. The aircraft descended and made contact with the runway with its landing gear. This contact caused the aircraft to veer to the left, drifting toward the southern boundary of the aerodrome. During the excursion, the left wing struck a shrub within a hedge, causing the aircraft to become unbalanced. The motor glider subsequently struck the ground and came to a halt in a nearby field. The aircraft was heavily damaged.
The investigation
The investigation focused on the pilot's takeoff technique and the aerodynamic conditions at the time of the accident. The pilot, who had extensive experience with this aircraft type, stated that he routinely performs takeoff accelerations at low altitudes with 8° flaps extended. He noted that he was actively struggling to counteract a wind from the south when the loss of control occurred.
Technical examination of the wreckage revealed no mechanical malfunctions or failures that could account for the loss of control. The aircraft's weight and balance were confirmed to be within the manufacturer's specified limits. Furthermore, the investigation reviewed the flight manual, which dictates that once the aircraft reaches 70 km/h during the takeoff roll, the pilot should transition to a normal climb gradient at 80 km/h.
Findings
- The primary cause of the accident was the use of an improvised and inappropriate takeoff technique, which failed to provide the pilot with sufficient altitude margin to manage aerodynamic turbulence.
- The pilot was attempting to maintain a level flight path at an extremely low height, leaving no room for error when encountering wind fluctuations.
- The aerodrome's visual approach charts specifically warn pilots of highly particular aerodynamic conditions, particularly when encountering winds from the south.