What happened
On December 29, 2019, a Zlin Savage Classic ultralight aircraft, registered as 05NJ, was conducting a private VFR flight in the Swiss Alps. The flight began at the Clariden-Hüfifir．irn mountain landing field, with the pilot and a passenger traveling toward Arosa. During the flight, the pilot performed several maneuvers around various mountain huts, capturing numerous photographs along the way.
As the aircraft approached the Tschuggenhütte, the flight path involved a left-hand turn. During this phase, the aircraft's airspeed decreased while the rate of climb increased. An eyewitness observed the aircraft becoming unstable around its longitudinal axis, banking sharply to the left, and entering a steep descent. The aircraft struck the snowy, rocky terrain approximately 180 meters east of the Tschuggenhütte. The impact caused the death of the pilot and left the passenger with serious injuries. The aircraft was destroyed in the crash.
The investigation
The SUST investigation utilized GPS data, handheld GPS records, and photographic evidence from both occupants to reconstruct the flight path. The investigation also examined the aircraft's configuration, noting it was equipped with a ski system and a specific trim weight. The inquiry also reviewed the regulatory framework regarding the operation of foreign-registered ultralight aircraft within Swiss airspace.
Findings
- The primary cause of the accident was the underspeeding of the aircraft during a turning maneuver. This was triggered by a simultaneous increase in climb rate and a turn into the slope at a low airspeed.
- The aircraft was operating under French registration, which meant it was not subject to Swiss airworthiness or pilot medical requirements, a factor identified as a risk enhancer for the region.
Safety action
Following the investigation, the SUST issued a safety recommendation to the Federal Office of Civil Aviation (BAZL) to implement measures ensuring that ultralight operations in Swiss airspace meet minimum safety requirements. This includes reviewing the registration and oversight of aircraft that do not meet Swiss airworthiness standards.