What happened
On August 4, 2017, a Piper PA-28-181, registration HB-PER, was conducting a flight as part of a youth aviation camp in the Engadine region. The aircraft departed Samedan Airport with three passengers on board. During the flight, the pilot decided to allow the passenger in the front right seat, who had no pilot training, to take control of the aircraft.
While flying near Pontresina, the pilot instructed the passenger to initiate a left turn. The aircraft continued climbing toward the Bernina Pass, reaching approximately 9,000 ft AMSL. The pilot then directed the passenger to fly south-southwest toward the Diavolezza area. As the aircraft approached the Corn Diavolezza, it was flying at a height of only about 25 meters above the terrain.
Following a steep right-hand turn, the aircraft descended below several overhead cables belonging to a cable car and telephone lines. The Piper PA-2SB-181 struck the ground with its right wing, causing the aircraft to break apart and the passenger in the rear right seat to be ejected. The aircraft overturned and came to rest 80 meters from the initial impact point. The accident resulted in 3 fatalities (the pilot and two passengers) and 1 serious injury to the remaining passenger.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined the flight data from the Flarm collision warning system, witness statements, and the aircraft's maintenance history. The investigation confirmed that the aircraft was in a valid condition for flight and that the weight and center of gravity were within limits. Investigators also analyzed the environmental conditions, noting that high temperatures and pressure at altitude had reduced the aircraft's climb performance by approximately 27% compared to standard atmosphere.
Findings
- The primary cause of the collision with the terrain was an inappropriate and risky mountain flying tactic.
- The pilot's decision to delegate aircraft control to an untrained passenger during a demanding phase of flight directly contributed to the accident.
- A systemic lack of safety awareness was identified among the camp organizers, as they had permitted a practice where passengers were allowed to handle controls without ensuring the pilots were qualified flight instructors capable of supervising such maneuvers.
- The pilot lacked specific advanced training in mountain flying, which led to a failure to properly account for terrain hazards and reduced performance capabilities.