What happened
On February 28, 2021, at approximately 13:45 local time, a Piper Aircraft Corporation, PA-18 "150", registered as HB-OKB, was conducting a private flight in the vicinity of the Glacier du Brenay in the canton of Valais. The aircraft was operating under Visual Flight Rules (VFR) on a flight path originating from and returning to Sion Airport (LSGS).
During the flight, the aircraft encountered a dangerous approach by a drone. The encounter occurred while the aircraft was maneuvering in the mountainous terrain of the region.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) initiated an inquiry into the incident to determine the circumstances surrounding the close proximity between the manned aircraft and the unmanned aerial vehicle (UAV). The investigation focused on the flight path of the HB-OKB and the trajectory of the drone at the time of the encounter.
Findings
The investigation established that the primary safety issue was a dangerous proximity between the aircraft and a drone. There were no injuries to the pilot or passenger, and no damage was sustained by the aircraft or any third-party property during the event.