atsb final report released 16 may 2013 - Ambulance Service of NSW

ANALYSISIntroductionThe ATSB identified that the crew were qualified for the flight and the helicopterand rescue winch were serviceable. In that context, this analysis will examine theoperational and organisational factors and risks associated with the development ofthe accident.Development of the accidentWhile on the ground at the staging area, the crew conducted deliberate planning forthe mission that was based on their prior assessment of the waterfall area. At theconclusion of this planning, all crewmembers were satisfied that the identifiedhazards had been adequately managed, and that the planned technique to retrievethe injured canyoner from the rock ledge was understood and acceptable to allinvolved.The time required for the duty paramedic to safely abseil down to the patientresulted in the winch retrieval commencing with the approach of last light. Theterrain associated with the waterfall and the possible presence of cloud cover meantthat the local time of last light probably occurred prior to the calculated time of2039. Although it was recognised during the crew’s planning that the approachingend of daylight might affect the mission, the pilot’s primary concern was to positionthe helicopter at the injured canyoner’s location in daylight, not with anyrequirement for the winch to be completed in daylight.The radio call from the duty paramedic as the helicopter returned from refuellingidentified that he and the patient were ready for an accompanied hypo strop lift. Theduty paramedic’s remark during this transmission that ‘…the tag line will be set byme…’ was more appropriate to, and generally associated with winching stretchers,rather than the intended recovery via rescue strop in this case. The duty paramedic’sremark may have been referring to the previously-agreed plan to control delivery ofthe winch hook to the supporting and then duty paramedic on the ledge below viathe yellow tag line. Equally, it may have been an unintended remark by the dutyparamedic that was made out of habit. This would have been consistent with theself-correction of his initial radio transmission that he was ‘…ready for anaccompanied stre [sic – possibly stretcher].., ah, accompanied hypo strop lift withequipment…’. However, as the intended use by the duty paramedic of the tag linewas not questioned by the flight crew, it was not possible to determine its meaning.As the air crewman (ACM) assisted the pilot to position the helicopter inpreparation for winching, the waterfall and sheer cliff adversely affected the pilot’shover reference. In response, the ACM guided the pilot to descend and repositionthe helicopter such that sufficient hover reference was established in the fadinglight. However, the resulting offset position of the helicopter meant that additionalwinch cable had to be fed out to reach the rock ledge than if the helicopter had beenable to hover directly overhead. In the event, the combination of the reported 150 ft(46 m) of deployed winch cable immediately before the fall, the reported angle ofthe winch cable away from the vertical at that time of about 30° to 45°, and theposition of the helicopter meant that, if the injured canyoner and paramedic fell- 37 -