The Australian Transport Safety Bureau (ATSB) has released its investigation of a Dec. 24, 2011 accident involving an AgustaWestland AW139 that was used in a winching operation for a seriously injured hiker at the bottom of a waterfall. The incident resulted in the patient and paramedic Michael Wilson being dragged along rock cliffs, resulting in the death of Wilson. The investigation highlighted a number of safety issues related to operational procedures, lighting, radio communication and risk assessment surrounding dusk/night-time conditions in potentially hazardous environments.
According to ATSB, the AW139 took off from Bankstown Airport in response to a personal locator beacon (PLB) alert in Budderoo National Park, which is around 16 km (about 10 miles) from Wollongong Airport in New South Wales. Two people had been climbing near Bridal Veil Falls when the rope holding up one of them failed, and he fell to the bottom of the falls. The other person sent out the PLB signal, and the Rescue Coordination Center of Australia (RCC) sent the AW139 in response.
After the helicopter crew arrived and determined that a direct winch operation would not be possible due to the terrain and vegetation, they flew to a staging area to devise a plan to rescue the injured hiker. The crew decided to winch two paramedics down to the top of the waterfall, where one of the paramedics (Wilson) would climb down to the injured hiker and the second would stay at the top of the waterfall. In addition to a climbing rope, Wilson took a second rope known as a tag line down with him, which would later be used to attach the patient to the helicopter. In order to stabilize the tendency for the object at the end of the rope (in this case the injured hiker) to swing like a pendulum, the team decided to use a stabilizing rope system.
Graphic showing a winch hook delivery using the tag line. From the ATSB report
Following the finalization of the plan including assessment of a number of equipment and lighting issues (as dusk was approaching), the helicopter moved into position to attempt the rescue. During the operation the air crewman (ACM) noted that he had received a hand signal from Wilson that he and the patient were ready to be winched. A short time later after pulling in the slack from the winch cable and the helicopter climbing 20 feet, the ACM reported that the pair had come off the ledge in a controlled manner, but that the stabilizing rope had appeared to fail. Wilson and the patient fell several feet onto a lower ledge before swinging toward the helicopter and striking a second rock at the base of the waterfall.
ATSB concluded that the reduced light, the helicopter’s positioning, adapting procedures and incomplete training were factors in the accident, along with organizational issues within the Ambulance Service of New South Wales and the helicopter operator, which both have since taken action to address the issues.
The accident sheds light on “the dangers associated with modifying established procedures to complete a difficult, and potentially not previously experienced, rescue task,” the ATSB report states, adding: “The use of procedures that are neither documented or trained for by crews makes it difficult to identify hazards and manage the related risks.”
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