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A police air wing operator has taken a range of safety actions in response to a helicopter winch training incident where a crewman was dragged overboard and briefly pulled through the water, an Australian Transport Safety Bureau investigation notes.
During a 29 September 2020 training exercise, a pilot, four tactical flight officers (TFOs) and a TFO instructor on board a Western Australia Police Air Wing Eurocopter AS365 Dauphin helicopter were conducting winching to a sea rescue vessel in waters off the Perth coastal suburb of Swanbourne.
During one exercise phase, a TFO performing the role of rescue crewman lost their footing on the deck of the vessel as it pitched and travelled over a wave, just as winching had commenced to bring them back on board the helicopter.
As the pilot began to separate the helicopter from the vessel, the winch cable became taut and the crewman was pulled overboard and dragged through the water for around six seconds.
Just prior to the crewman’s fall, the winch operator had correctly called ‘winching in’. However, seeing the crewman had fallen on the deck, the winch operator called ‘crewman has fallen’.
The pilot subsequently advised the ATSB they commenced moving the helicopter away from the vessel in response to hearing the ‘winching in’ call, expecting the usual sequence to continue as had occurred on previous occasions that day.
The pilot acknowledged this was not consistent with procedure, which was to wait until the winch operator called ‘clear to move back and left’.
In addition, once the crewman had been pulled overboard, the winch operator called for the helicopter pilot to ‘hold’, intending for the helicopter to hover over the crewman in the water, instead of announcing ‘crewman overboard’, as per the procedure. The pilot interpreted the ‘hold’ message as meaning to hold position with reference to the moving vessel, which resulted in the crewman being dragged through the water. The crewman, once winched into the helicopter, confirmed they were uninjured.
“The ATSB found that, although the winch operator communicated that the crewman had fallen, this was not recognised by the pilot, who expected the usual sequence to continue as had previously occurred on numerous occasions that day during earlier training phases,” said ATSB Director Transport Safety Dr Mike Walker.
“As a result, the pilot instinctively increased the distance between the helicopter and vessel, and the rescue crewman was dragged overboard by the winch cable.”
In addition, the ATSB found that the operator did not regularly brief or practice crewman overboard drills during vessel winching training.
This contributed to a breakdown in communication during the incident, and reduced the crew’s preparedness to respond effectively to such an event.
“Effective communication between pilots and crewmen is critical when undertaking helicopter winching as the pilot is required to safely manoeuvre the aircraft while unable to visually monitor the progress of the activity,” Dr Walker said.
“Even during highly-trained and well-rehearsed operations, human performance limitations such as expectancy and reduced attention associated with a familiar task, together with deviations from standard phraseology, can have undesired outcomes.”
Separately, and though not a factor contributing directly to this event, the ATSB found that changes to sea state limitations – i.e. the severity of sea and swell conditions – that could be allowed during training exercises had been approved without the required review by the operator’s Safety Action Group.
“The absence of that review reduced the opportunity to identify any increased risk associated with the change,” Dr Walker said.
Following an internal investigation in response to the incident, the WA Police Air Wing has introduced a range of safety actions, including amending training and pre-flight briefings to include a crewman overboard scenario, and implementing crewman overboard drills during winch simulation training.
The Police Air Wing also concluded that the inherent risk of open water vessel winching outweighed the operational benefit. Consequently, it will no longer conduct open water winching to small vessels underway. Instead, to conduct an emergency response to a small vessel, it will deploy a rescue raft while winching or helocasting* a rescue crewman to the water.
This eliminates the risk of transferring persons to small vessels underway while still maintaining the same level of rescue capability to the community when required.
* Helocasting is where a crewman jumps from the helicopter at a low altitude and speed into the water.
Read the report: Helicopter winching incident involving Eurocopter AS365, VH-WPX, near Swanbourne, Western Australia, on 29 September 2020