What happened
On November 23, 1999, an Eurocopter SA315B Lama, registration HB-XRE, was performing commercial cargo transport operations near Mayen du Scex, Switzerland. The mission involved transporting long logs via a 30-meter sling to a drainage worksite.
After completing several rotations, the helicopter arrived to deposit the final load consisting of two large bags. Once the bags were emptied and the pilot began a departure maneuver, a single log remained trapped inside one of the bags. As the aircraft climbed, the log fell from a height of approximately 8 meters. At that moment, a ground worker moved toward the newly deposited pile of wood, crossing the path of the suspended slings. Although a flight assistant attempted to shout a warning, the noise of the helicopter masked the alert. The log struck the worker in the head, causing grievously injured status, and the impact caused him to fall face forward, resulting in further serious facial injuries.
The investigation
The investigation examined the safety protocols and equipment present at the worksite. It was established that while the flight assistant regularly reinforced safety instructions, the ground workers were not equipped with radio receivers to communicate with the crew. Furthermore, the investigation looked into the use of protective headgear on-site. While safety helmets were available in a container several hundred meters away, the workers were not wearing them at the time of the accident. The investigation also noted that the available helmets lacked chin straps, making them prone to blowing off due to rotor wash.
Findings
- The accident was triggered by the unpredictable behavior of a worker who failed to maintain focus on the overhead loads during the aircraft's departure.
- The worker's movement into the danger zone was likely motivated by a desire to reach a colleague following the final rotation of the day.
- The lack of appropriate personal protective equipment (PPE) contributed to the severity of the incident; specifically, the absence of a suitable helmet meant the head injury was more severe.
- The ground workers lacked radio communication equipment, which would have allowed them to receive direct warnings from the flight assistant.
Safety action
- The investigation noted that the available construction helmets were unsuitable for helicopter operations because the lack of chin straps caused them to be displaced by rotor wash.
- It was established that the failure to adhere to established safety protocols, such as monitoring the aircraft's movement, should ideally result in the suspension of work.