What happened
On January 18, 2003, two Piper PA-18 "150" aircraft were conducting mountain flight training on the Rosa-Blanche Glacier near Nendaz, Switzerland. The first aircraft, HB-ORK, was performing a training flight for a student pilot, while the second aircraft, HB-ORN, was conducting landing and takeoff practice.
Initially, the two crews maintained effective separation by performing staggered landings and takeoffs on the upper part of the glacier. However, the sequence of events changed when the pilot of HB-</strong>ORN decided to perform a third landing on the lower section of the glacier. During this maneuver, the pilot lost visual contact with the other aircraft. Simultaneously, the crew of HB-ORK initiated a takeoff from the upper glacier, operating under the assumption that HB-ORN was still in the pattern. As HB-ORK accelerated and crossed the crest toward the lower glacier, it encountered HB-ORN during its final approach. The two aircraft collided with their right wings striking one another. The impact caused two serious injuries to the crew of HB-ORK, while the occupants of HB-ORN remained unharmed.
The investigation
The investigation examined the flight paths, radio communications, and the topographical constraints of the Rosa-Blanche Glacier. Investigators reviewed the technical condition of both aircraft and the radio logs from the mountain frequency 130.350 MHz. The inquiry also assessed the visibility and the impact of the glacier's terrain on pilot situational awareness.
Findings
- The topography of the Rosa-Blanche Glacier prevents a complete view of the upper landing area from the lower landing area.
- While both crews broadcasted their intentions over the radio, the loss of coordination regarding planned departures and arrivals led to the collision.
- The pilot of HB-ORN shortened the approach to land on the lower glacier, which resulted in a loss of visual contact with the other aircraft.
- The crew of HB-ORK proceeded with a takeoff from the upper glacier believing the other aircraft was still part of the established sequence.
- There were no technical defects found in either Piper PA-18 "150" aircraft, and both were properly equipped for mountain operations.