Swiss Investigation of AS 350 B2 Helicopter Accident at Petersgrat (HB-ZTM)

Overview and Aircraft Details On 13 May 2017, an AS 350 B2 helicopter, registered HB-ZTM, was involved in an accident at the mountain landing site Petersgrat (LSVP) in the municipality of Blatten, Valais, Switzerland. The aircraft was operated by Mountain Flyers 80 Ltd. and owned by Kunert Aircraft Asset GbR. The pilot, a Swiss citizen born in 1973, held a Private Pilot Licence (Helicopter) issued by the Federal Office of Civil Aviation (BAZL) under EASA regulations. ## Flight Operations and Accident Circumstances The flight was a private Visual Flight Rules (VFR) operation that departed from Bern-Belp (LSZB) at approximately 09:50 local time. The helicopter carried the pilot and five passengers. During the approach to Petersgrat, the pilot flew past the landing site at approximately 10,800 ft AMSL before turning for a final approach. The accident occurred at 10:16 local time during the landing phase. The investigation determined the accident type was a loss of control resulting in the helicopter overturning onto its side. ## Casualties and Damage The accident resulted in one fatality among the occupants and three minor injuries. The aircraft was destroyed. Minor third-party damage was reported, consisting of slight terrain contamination from leaked operating fluids. The investigation was conducted by the Swiss Transportation Safety Investigation Board (STSB) to prevent future accidents, in accordance with ICAO Annex 13 and Swiss aviation law.