What happened
On September 26, 2000, at approximately 16:30, a mid-air collision occurred over a football field in Beuson, Switzerland. The accident involved two helicopters, an Alouette III SA316B, registration HB-XJR, and a Jet Ranger II AB206B, registration HB-XNU, both operated by Air-Glaciers SA. The aircraft were performing short-duration sightseeing flights for a group of approximately 150 tourists.
The collision took place during the final approach phase. The pilot of the HB-XNU was executing a flight pattern that had been modified from a previous rotation. Simultaneously, the HB-XJR was approaching the landing site from a different direction. The impact caused the HB-XJR to lose lift and crash inverted, resulting in 7 fatalities (one crew member and six passengers). The HB-XNU lost its tail rotor upon impact, causing it to spin and crash on the field. This aircraft also sustained 3 injuries (one passenger died, one crew member and one passenger were seriously injured, and one passenger sustained minor injuries).
The investigation
Investigators examined the flight operations, communication between the crews, and the organizational structure of the event. The investigation established that the flight schedule had been delayed by approximately one hour due to the late arrival of the passengers, which led to a compressed flight schedule.
Technical analysis of the flight paths showed that the two aircraft were on converging trajectories. The investigation also reviewed the instructions provided by the chief pilot, noting that while the pilots were informed of the mission, specific detailed instructions regarding separation and flight strategy were not provided. Furthermore, the investigation looked into the role of the flight assistants on the ground and the lack of a formal regulation for managing multiple aircraft performing simultaneous operations at a single site.
Findings
- The primary cause of the accident was a failure to maintain adequate separation between the two helicopters and insufficient monitoring of the airspace.
- The pilots exchanged vague and inadequate flight instructions regarding flight paths, separation, and reporting points.
- There was a lack of clear organization and formal regulations from the organizer for conducting this type of multi-aircraft operation.
- Contributing factors included potential sun glare affecting the pilot of the HB-XJR during approach.
- The pilot of the HB-XNU was positioned in a blind spot relative to the HB-XJR due to their respective positions.
- The operational pressure caused by the program delay and the resulting haste contributed to the incident.
Safety action
To prevent future collisions during similar operations, the investigation established that when multiple helicopters are deployed at the same work site, a ground assistant must be mandatory to monitor the aircraft and ensure separation.