What happened
On April 5, 2009, a DG-500 ELAN ORION, registration HB-3292, was performing an aerobatic flight program near Chamoson, Switzerland. After taking off from Sion airfield, the pilot began a series of maneuvers, including a loop and a roll, at approximately 180 km/h. While attempting to transition into a flying roll, the pilot encountered a significant issue: the control column became increasingly resistant to movement and eventually reached a point where it could not be pulled back to reduce speed.
Unable to maintain a level attitude and facing a loss of pitch control, the pilot notified air traffic control of the emergency. After communicating with the flight club, the pilot decided to abandon the aircraft. Despite difficulty opening the canopy, the pilot successfully exited the glider and deployed a parachute, landing safely on a roadside embankment. The glider subsequently crashed into a vineyard area near Les Îles de Chamoson, resulting in the destruction of the aircraft.
The investigation
Investigators examined the aircraft's configuration and the pilot's preparation. The glider had been configured for aerobatics by removing wingtips to reduce the wingspan to 17.2 meters. The investigation focused on the mechanical failure of the flight controls and the cockpit's internal components.
Technical analysis revealed that the rear seat headrest had tilted forward during the maneuver. This movement caused the headrest to physically obstruct the travel of the elevator control column. Furthermore, the investigation looked into the maintenance and documentation standards of the club, specifically regarding the aircraft's flight manual and pre-flight inspection procedures.
Findings
- The primary cause of the accident was performing aerobatic maneuvers in a glider that was not properly equipped, leading to the blockage of the elevator control column.
- The rear seat headrest was not secured with the required safety cords, which allowed it to tilt forward and obstruct the control column.
- The pilot was unaware of the specific risk regarding the headrest causing a control blockage.
- The pre-flight inspection was incomplete, as the specific check for the headrest security was not performed.
- The aircraft was carrying an outdated version of the flight manual (dated 1995) which lacked the necessary inspection point for the headrest.
- The pilot's lack of proficiency in German prevented him from utilizing the updated manufacturer documentation or technical communications.
Safety action
- The investigation noted that the design of the headrest attachment on the DG-500 model was inherently prone to such issues, a flaw addressed in newer models like the DG-1000.
- The investigation highlighted the necessity of ensuring all pilots have access to and understand the most recent flight manuals and safety directives in a language they can comprehend.