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

The ACM recalled that the winch on VH-SYZ had operated normally throughoutthe operations on 24 December 2011. He advised being aware of the winchcharacteristics should the overload clutch activate, and did not believe that theclutch activated during the attempted winch retrieval of the duty paramedic andinjured canyoner.Meteorological informationThe Bureau of Meteorology conducted an analysis of the likely weather conditionsin the vicinity of the Bridal Veil Falls at the time of the accident. That analysisconcluded:Upon examining all the meteorological observation and analyses, it isconsidered that the weather conditions at the location at the time of theincident were of light winds, with no precipitation, significant low cloud orother visibility reducing phenomena present. The temperature was between20.5 and 22.5 degrees Celsius and the QNH [atmospheric pressure] wasbetween 1012 and 1013 hPa. From the upper wind and temperatureobservations it is also evident that there was no significant turbulence or icingpresent.The ACM reported that there was localised low cloud in the vicinity of the waterfallwhen the crew were on the ground at the staging area planning the recovery of theinjured canyoner. He recalled that it was still present when they returned to thewaterfall after refuelling; however, as the evening progressed the cloud dissipatedto a fine evening. The ACM’s observations were consistent with those of a localNational Parks and Wildlife Service (NPWS) field officer who assisted with theground recovery.Last light on the day of the accident was at 2040. 18 With regard to the determinationof last light, paragraph 1.2 of GEN 2.7 SUNRISE/SUNSET TABLES of theAeronautical Information Publication stated:...parameters used in compiling the Daylight and Darkness Graphs do notinclude the nature of the terrain surrounding a location, or the presence ofother than a cloudless sky and unlimited visibility at that location.Consequently, the presence of cloud cover, poor visibility or high terrain tothe west of an aerodrome will cause daylight to end at a time earlier than thatextracted from the appropriate graph.Site and equipment examinationOn-site examinationThe access sequence to the waterfall area in support of the ATSB’s investigation isdetailed in Table 1. The ATSB is aware of a number of other visits by variousparties to the top of the waterfall that were undertaken for purposes other thanassisting its investigation. However, the ATSB is satisfied that none of these partiesinterfered with or touched the equipment used by the canyoners or the dutyparamedic.18Last light was computed using the National Aeronautical Information Processing System.- 21 -