According to a note released by the Valais police, a helicopter accident occurred on Saturday afternoon at around 13:20 in Vétroz/VS. The aircraft involved is the Guimbal Cabri G2 HB-ZLX. 
On board was an instructor, a 41-year-old Fribourg man living in the lower Valais, who was transported by ambulance to the hospital in Sion. The student pilot, a 62-year-old Spanish citizen living in Canton Geneva, was not injured. The helicopter was severely damaged.
The causes of the accident are under investigation.
A few hours earlier, a helicopter had tipped to one side on landing at the Sitterdorf TG airfield. The 30-year-old pilot and three passengers aged between 23 and 60 were uninjured. 
Under Article 98 of the Aviation Act, the Office of the Attorney General of Switzerland is responsible for the prosecution of offences committed on board an aircraft.
In order to clarify the exact course of events and the cause of the accident, experts of the Swiss Transportation Safety Investigation Board (STSB) have opened an inquiry.
The investigation is being conducted with the support of the public prosecutor's office and the Valais cantonal police.