Incident Overview
On 21 June 2013, a serious incident involving two helicopters occurred approximately 3 nautical miles southwest of Mollis Airfield (LSMF) in the canton of Glarus, Switzerland. The incident, classified as a near collision, involved a Eurocopter EC120B (registration HB-ZBB) operated by BB Heli AG and an AgustaWestland AW109SP (registration HB-ZRY) operated by the Swiss Air-Ambulance AG (Schweizerische Luft-Ambulanz AG).
Aircraft and Crew
HB-ZBB (Eurocopter EC120B) was crewed by a pilot and a flight instructor. HB-ZRY (AgustaWestland AW109SP) carried a pilot and a helicopter crew member (HCM). Details of their flight experience were documented in the investigation.
Circumstances
The incident occurred during daytime visual meteorological conditions. The exact sequence of events leading to the near collision was examined by the STSB. Both helicopters were equipped with transponders and collision avoidance systems. The investigation included analysis of flight data recorders, radar data, and the FLARM/Floice collision warning devices installed on each aircraft.
Investigation Findings
The STSB conducted test flights to assess visual detectability and the performance of the traffic advisory systems. The investigation also examined the configuration and installation of the FLARM devices, as well as the airspace structure and communication procedures. The final report (No. 2233) detailed the findings but did not assign a specific probable cause.