| Case 7: Kilsbys Sinkhole |
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Reprinted from Cave Divers Association of Australia (CDAA) Report, 2012 The victim (age 51) and his buddy arrived in Mt Gambier on the evening of Thursday 11th March 2010. They were both cave rated, had no other known technical diving qualifications, and had been occasional dive buddies together for the past 9 years. The victim was first qualified as a Category 1 diver in 1981, and progressed to cave level in 1995. On the Friday they had an uneventful dive in each of The Pines and Fossil Cave. On this trip to Mt Gambier, the victim was using a recently purchased sidemount harness and new regulators. He had not dived sidemounts before. However, the dives in The Pines and Fossil Cave were apparently incident free. The only problem that arose on this day was a fall and injury to the victim’s 5th left toe, which required Panadeine as treatment. It was also noted that the victim was not himself that weekend, appearing quiet, withdrawn and not his usual cheerful self. After a quiet Friday night the divers went to Kilsbys Sinkhole near Mt Gambier on the Saturday morning. Kilsbys is a large clear sinkhole of approximately 65m maximum depth that the pair were quite familiar with. A permanent line was installed in the cave in a triangle shape, with the apex (00) down the slope below the pontoon at 25m,and the base running across the back of the cave (see map below). Their plan was to dive to a maximum depth of 40m on air, using a nitrox travel gas and a shared cylinder of nitrox 80% hanging on a shotline below the pontoon. During the preparations for the dive, his buddy reported that the victim was still not himself. He remained very quiet and seemed to be disorganised. His buddy had to remind him of several minor issues during this time and hence the victim took significantly longer than the buddy to prepare. Finally they descended together and the buddy noted the victim to appear clumsy and uncomfortable during the descent. The pair staged their smaller travel cylinders at “B” on the permanent line at 35m (well past the MOD of one of the cylinders) and then headed towards the deeper corner of the sinkhole towards “C”. Soon after this, the victim stopped responding to signals and seemed compromised. The buddy then dropped down to 45m, away from the victim, and after 2 minutes 30 seconds the victim joined him at that depth. The buddy then swam further down to 52.3m during which time the victim became inverted in his dry suit. After a separation of approximately 3 minutes, the buddy swam back to the victim and helped him get upright and settled again. During this process, the peg holding the fixed line at “C” was pulled out, and the buddy subsequently replaced it. The divers then swam back along the permanent line towards “B” with the buddy leading. The victim was slow to follow but finally swam past the buddy and the travel cylinders lying nearby. The buddy collected the 2 cylinders but then turned to see the victim going inverted again. In the process of trying to assist, the buddy lost his mask and in the ensuing moments, made a poorly controlled ascent to the surface without his mask, ascending along the cave ceiling. On arrival at the surface, he replaced his mask, reset his computer to nitrox 80% and descended on the shot line to commence his missed decompression. At this point he was badly shaken. Looking down, the victim was seen to be swimming towards the shallower part of the cave but he then became inverted again and subsequently stopped breathing and drowned. The body recovery was performed by the SAPOL Water Operations Unit with advice from a local CDAA member. On recovery, the victim was found to be severely entangled in the permanent line (00-A). His two sidemount cylinders were completely empty. Accident Analysis
More information on Kilsbys Sinkhole
 Kilsbys Sinkhole | Map: Peter Horne & Richard Harris |