What happened
On 6 August 2004, an ASK13 glider, registration FWN, was performing a trial lesson at Booker, Wycombe Air Park, when it experienced a sudden loss of control during takeoff. The flight was part of a group of students participating in a trial lesson program. During the takeoff roll, the aircraft encountered a bumpy surface, causing a camera placed on the cockpit floor by the student to shift.
As the glider became airborne, the instructor found himself unable to move the control column forward to correct an increasing pitch angle. The tug aircraft pilot noted a progressive heave, similar to the deployment of airb/rakes, as the glider climbed steeply. The glider subsequently stalled, dropped a wing, and entered a descending turn. After striking the ground and bouncing back into the air, the aircraft performed a second stall and impacted the ground in a near-vertical attitude. The student sustained serious injuries to both legs, while the instructor suffered minor injuries to his chest and back. The aircraft was destroyed.
The investigation
Investigators examined the wreckage and the cockpit of the ASK13. They discovered that the student's camera had been damaged and found a fragment of black material in the edge of the cockpit floor that matched the camera case. The investigation established that the camera had become wedged in the gap between the aft edge of the cockpit floor and the front seat control column. This gap had widened when the instructor moved the control column to its full aft position during pre-takeoff checks.
Further examination of the flight procedures revealed that while the British Gliding Association (BGA) provides guidance on securing loose articles, the instructor was not aware the student had brought a camera. The investigation also noted that the student had placed the camera on the floor between his feet, an area that may have been outside the instructor's direct line of sight during the briefing.
Findings
- The primary cause of the accident was the camera becoming lodged in the control column mechanism, which prevented the instructor from applying the necessary forward pressure to the controls.
- The camera moved into the gap because the aircraft encountered bumps during the takeoff roll on the grass runway.
- The instructor was unaware that the student was carrying a loose article in the cockpit.
- The student had placed the camera on the floor rather than securing it according to BGA recommendations.