What happened
On July 29, 2003, at approximately 14:40 local time, two gliders collided head-on while participating in an Alpine soaring training camp. The first aircraft, a DG-50/22 ELAN with registration HB-1994, had departed from Zweisimmen carrying two pilots. The second aircraft, an ASW 20L with registration D-6805, had launched from Saanen earlier that afternoon.
The collision occurred at an altitude of approximately 2,700 meters near the Walliser Wispile, in the municipality of Gsteig. The two aircraft were flying on converging paths; the D-6805 was traveling south at 210 degrees, while the HB-1994 was heading north. The impact was a direct frontal collision. The pilot in the rear seat of the HB-1994 and the pilot of the D-6805 managed to deploy their parachutes and survive the accident, though the latter sustained a broken leg upon landing. Tragically, the pilot in the front seat of the HB-1994 was unable to escape the wreckage and died as a result of the impact or the subsequent crash.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) conducted an investigation alongside local police. Investigators examined the wreckage of both aircraft, which were both destroyed in the accident. No technical defects were found in either glider, and no evidence of mechanical failure was identified in the control surfaces or structural components.
Medical examinations of the surviving pilots showed no traces of alcohol, drugs, or medication. The investigation also reviewed the flight conditions, noting that while visibility was excellent (approximately 20 km), the pilots were flying against a background of mountains and clouds that made detection difficult. The investigation also noted that the pilot of the D-6085 was relatively new to the Saanen area, having only completed an orientation flight two days prior.
Findings
- The primary cause of the accident was that the pilots detected each other too late to take effective evasive action.
- The frontal approach of the two aircraft meant that they were only visible as silhouettes, making them extremely difficult to identify at a distance.
- The presence of white or grey backgrounds (such as clouds or bright mountain slopes) significantly reduced the visibility of the white gliders.
- While the aircraft featured high-visibility warning colors on the wingtips and nose, these were found to be of limited effectiveness in preventing a collision during a head-on approach.
Safety action
- The Federal Office of Civil Aviation (FOCA) should review methods to reduce collision risks in Swiss airspace, such as the implementation of appropriate warning systems.
- Following the observation that the use of parachutes allowed two pilots to survive, the authorities should review whether the requirement for glider pilots to wear parachutes should be reinstated.