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February 2000 Vol. 15, No. 2   RSS Feed for Undercurrent Issues
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Dive Gear and Dive Deaths

equipment problems? or diver error?

from the February, 2000 issue of Undercurrent   Subscribe Now

How often do you read or hear about equipment failure as the cause of an accident? Not often, because the industry seems to prefer us to believe its always an erring diver who causes his own death, never equipment. And theres no data collected in the U.S. to prove or deny the claims. While DAN discusses deaths in medical terms as well as in terms of diver error, it doesnt go into much detail about equipment causes.

DAN could contribute more to diver safety if it would take the tack of the Australians, who recently analyzed 1000 incidents, finding that 105 (more than 10 percent) were pure equipment failure, a percentage similar to incidents in aviation, medicine, and industry, where studies show that 8-10% of the Dive Gear and Dive Deaths equipment problems? or diver error? incidents arise from equipment failure. In diving incidents, most equipment problems are associated with equipment misuse, lack of understanding of how the equipment functioned, or poor equipment design, maintenance, and servicing.

For diving safety, control of equipment problems is critical. While it is inevitable that some equipment will malfunction, true equipment failure occurs when a piece of equipment fails to perform in the manner specified by the manufacturer, providing that it had been maintained and checked prior to use in accordance with the manufacturers recommendations. It is often unclear whether there was a true equipment malfunction or if the problem arose because of equipment misuse or misassembly.

The Australians define an incident as any error that could have or did reduce the safety margin on a particular dive. An error can be related to anybody associated with the dive and can occur at any stage.

Among the 1000 incidents reported, 105 involved equipment failure and in 27, the diver died. Fifty-four percent involved the regulator and air supply, 23% the BC, 13% computers and depth gauges, and 10% other equipment. DCS was the most common cause of death (14), while pulmonary barotrauma, embolism, ear barotrauma, and drowning were also causes .

Air gauge failure was a major cause of death, failing most often in the latter stages of a dive when air pressure was low. First-stage regulator failure and low-pressure hose rupture occurred at all air pressures, not just when the tank was full. Six of the first-stage failures and six low-pressure hose ruptures occurred at depth.

In two incidents, an alternate air source (a power inflator and demand valve combination) developed a leak during the dive (a pre-dive check would not have detected this fault), requiring disconnection to preserve the divers air supply. Two other alternate air source incidents involved the failure of the filling mechanism for small pony bottles such as a Spare Air.

In fourteen incidents, the BC power inflator failed to operate (a pre-dive check would have detected this fault in most cases). In ten incidents, the inflator spontaneously inflated the BC: in seven of these cases, the diver failed to slow the rapid ascent and died. Unfortunately, not all BCs have an accessible emergency dump valve that can exhaust air at a rate at least equal to that of maximum inflation. Manufacturers should add a cutoff mechanism to the power inflator to prevent the rapid depletion of air.

Of the eleven computer incidents, six led to death. To prevent sudden power failures, all computers should be equipped with either a low-battery alarm or a mechanism by which the diver can test battery power.

All of the incidents involving inaccurate depth gauges caused death. Even when a depth gauge is first purchased, the accuracy of the gauge is not known, so divers should assess accuracy by comparing the readings with those of their diving companion before, during, and after dives. Furthermore, gauges should be recalibrated annually.

The loss of a fin can be fatal, so a pre-dive check must include the fin straps.

Safety sausages are usually visible and easily maintained in an upright position in calm conditions, but they may fail to remain upright in strong winds and so become invisible. They need to be made from sturdy material and tested in all conditions.

Conclusions

Of the 105 incidents, sixtythree could have been prevented by a thorough pre-dive check and annual equipment recalibration. Another fifty-five could have been avoided if there was a change of manufacturing material and testing procedure or the equipment design was altered (the addition of a lowbattery alarm in dive computers, an audible low-pressure alarm in air gauges and tank pillar valves, a larger, more accessible emergency dump valve in all buoyancy jackets and a cutoff mechanism to the power inflator).

Adherence to established diving safety procedures could have reduced the effect of fiftythree incidents, 51% of the total. The effect of another forty-eight incidents (46% of the total) could have been minimized by using backup equipment such as a dive timer, depth gauge, and light. If a piece of equipment is considered essential, it is reasonable that at least one level of redundancy (e.g., duplicate equipment) is needed, which is the attitude of Cave Diving Associations worldwide.

Equipment problems, then, are real. Diver error is not the only cause of death. While divers need to maintain their equipment and have it regularly serviced, the manufacturers must do more to build fail-safe gear.

Ben Davison

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