Photo courtesy of the ATSB
A fatal aeromedical accident in Australia that killed a specially-trained paramedic points out the dangers of modifying procedures on the spot to complete a difficult mission, according to two separate investigations.
“This accident highlights the dangers associated with modifying established procedures to complete a difficult, and potentially not previously experienced, rescue task,” the Australian Transport Safety Bureau said, adding that “specifically, the use of procedures that are neither documented nor trained for by crews makes it difficult to identify hazards and manage the related risks.”
The accident also raises a broader issue for the helicopter rescue community, which is posed in the Australian Transport Safety Bureau’s 2013 report on the accident: Do the greater capabilities of helicopters and hoists increase the likelihood that complex rescues will be attempted that go beyond the current training and procedural support provided to rescue personnel?
|Bridal Veil Falls, the scene of a preventable death caused by mismanaged risk. Photo courtesy of the ATSB
The 2011 accident at Bridal Veil Falls in Budderoo National Park occurred when the paramedic and his patient were pulled by the helicopter’s cable from a rock ledge and plummeted about 245 feet to the base of the falls. The patient had serious but not life-threatening injuries at the start of the rescue attempt; he survived the fall. The paramedic suffered severe injuries and died where he lay shortly after the fall.
The ATSB investigation (AO-2011-166) found several factors contributed to the accident, including the ad hoc adaptation of approved procedures to support the attempt, low light conditions and the helicopter’s position during the rescue attempt, the aircrew member’s lack of familiarity with his aircraft’s radio system and the lack of training in night winch operations.
Like the second investigation, by the Coroner’s Court of New South Wales, the ATSB discussed numerous risks that were mismanaged by the rescue crewmembers and their employers. The safety bureau noted “the flight crew considered that the winching operation was proceeding safely up until the fall occurred.”
However, the coroner’s inquest discusses the mismanaged risks in more detail. For instance, while the ATSB “found that the crew was qualified for the flight,” the coroner’s inquest found that the paramedic’s qualification in the “Hi-line” winching procedure adapted on the fly during the mission had expired. According to the helicopter operator’s standard operating procedures, the inquest found, the paramedic was not permitted to do that winching procedure without explicit permission from the chief pilot (which he did not have).
“The absence of such permission was reason [enough] for the pilot to terminate the procedure,” the inquest report said.
The events leading immediately to the accident began at about 1615 on Dec. 24, 2011, when a man’s rappelling rope failed and he fell to the rock ledge about 50 feet from the top of Bridal Veil Falls. His partner activated a 406-MHz emergency personal locator beacon at about 1635 local, and the Rescue Coordination Center Australia asked the Ambulance Service of New South Wales (ASNSW) to launch a rescue helicopter to track to the beacon.
ASNSW employed and trained the paramedic (assigned as the duty paramedic on the mission), a doctor and a backup paramedic. CHC Helicopters (Australia) provided the aircraft (an AgustaWestland AW139 fitted with a Goodrich hoist) as well as the pilot and aircrew member/winch operator under contract to ASNSW. CHC also provided some training to the medical crewmembers.
Because the reported patient location was difficult terrain, the paramedic asked a support paramedic to join the flight. Both were certified as part of the Special Casualty Access Team (SCAT), which ASNSW developed about 30 years ago to enable paramedics to access patients in hazardous or remote locations, perform triage, treat the patients and evacuate them.
The AW139 (“Rescue 24”) was on the scene about 1735. The crew determined the terrain and vegetation made it impossible to lower the paramedic directly to the patient and perform a vertical hoist. The pilot landed nearby so the crew could plan the rescue.
They decided to place the two paramedics at the top of the falls and the duty paramedic would rappel down to the patient. He would take one end of a rope while the backup paramedic held the other. The backup would tie the rope to the winch hook, then the duty paramedic would use his end to pull the hook over when it was lowered to him. The helicopter would hover at an angle to the ledge. Then the paramedic would rig a rope system to stabilize any swinging motion when he and the patient were winched off the ledge until the two were in position directly below the helicopter.
The plan was based on a previous, high-profile rescue performed by another operator, the ATSB said. ASNSW management told the ATSB the there was no documentation or training for the hook-delivery or winching methods and neither had been tried prior to this case.
The aircrew member and crew doctor had concerns about the plan, the ATSB said, but were “assured by the other crew members that the rescue plan was not exceptional in emergency medical service” and “was a technique that had been used before.”
Before attempting the rescue, the ATSB said, “the entire crew agreed with the plan for accessing and retrieving the patient.”
The attempt did not begin until about 2020. Local “last light” was projected at 2040. The inquest report notes that the Rescue 24 crew was attempting a rescue 130-160 feet below the top of a nearby cliff, “which cast the base of the falls in deep shadow for much of the day.”
At 2038, when the pilot asked what the duty paramedic was doing, the aircrew member said he couldn’t see because the paramedic “was in a dark hole.” The ATSB said the conversation was captured on the AW139’s multi-purpose flight recorder.
The aircrew member then said that the duty paramedic had signaled with his hands that he was ready for winching. The two had been unable to talk by radio because the aircrew member was unfamiliar with the AW139’s radio system. He was “only very recently qualified on the AW139” and this mission was his “first rescue operation with this crew” and his “first operational winch rescue on the AW139,” the inquest said. When the winching began, 150 feet of cable was running at a 45-degree angle from the aircraft to the ledge, at roughly a 3 o’clock position. Goodrich specifies a maximum 15-degree angle for that hoist. The aircrew member announced he was “winching in the slack.” He also directed the pilot to climb 20 feet.
A short time later, the aircrew member told the ATSB, he saw paramedic and patient move out from the ledge “in a controlled manner.” They then fell about 10 feet to another ledge before swinging out under the helicopter.
The aircrew member winched in the cable at full speed and directed the pilot to move the helicopter left. The paramedic and patient fell about 100 feet onto boulders. ATSB investigators found no evidence that the paramedic had set up a rope-and-anchor system to stabilize movement while on the cable.
The inquest also noted that the rescue plan went beyond winching procedures specified in CHC’s standard operating procedures.