What happened
On August 9, 1961, a Dornier-Werke GmbH flight crew was conducting ski-equipped testing of a Do-28 aircraft. Originally, the testing program was intended for the Forno Glacier; however, due to unsuitable conditions at that location, the crew decided to move operations to the more challenging Vadretin da Tschierva glacier in the Grisons region of Switzerland.
Following an initial landing at 09:44, the aircraft prepared for a second approach. During this second attempt, the pilot initiated a glide from approximately 10,900 feet. While the pilot expected a descent, the aircraft encountered unexpected updrafts and a strengthening tailwind, which increased the approach speed from 70 to 80 knots. The aircraft flew over the intended touchdown point at an altitude of roughly 30 meters, with the engine nacelles obstructing the view of the landing markers.
At 10:10, the left ski made contact with the ground approximately 400 meters past the intended landing zone on a steep upward slope. The momentum caused the Do-28 to flip over, resulting in the destruction of the airframe. The two occupants on board sustained minor injuries.
The investigation
The investigation focused on the decision-making process regarding the change of landing site and the pilot's management of the approach. Investigators examined the weather conditions, noting that winds had increased to peaks of 12 m/s (over 20 knots) with significant updrafts. The inquiry also reviewed the pilot's qualifications, noting that while highly experienced in general flight, the pilot lacked specific, systematic training for glacier landings and had not previously flown at this specific glacier.
Findings
- The primary cause was the pilot approaching the glacier landing site at an excessive altitude and speed.
- A critical contributing factor was the misjudgment of the intensifying tailwind and the resulting updrafts.
- The pilot's specific skills and training were insufficient for the high technical demands of landing on this particular glacier terrain.
- Visibility of the landing markers was compromised by the aircraft's engine nacelles during the final approach.
Safety action
While the investigation noted that the pilot's lack of systematic glacier flight training was a factor, no specific regulatory safety recommendations were formally issued in this report.