Staying Alive on Rebreathers: It Really Is All About Set-Up
By Steve Lewis
During the proceedings of Rebreather Forum 3.0 in Orlando, two things quickly became obvious to the dive professionals who travelled to Florida from as far afield as Australia to attend: the popularity of and interest in rebreather diving is growing exponentially, and rebreather safety is a concern to both manufacturers and certifying agencies (such as TDI, who had many staff members and ITs attending the conference last May).
There is no denying that rebreathers seem to account for more than their share of reported accidents – serious and otherwise. The number of rebreather divers worldwide – based on numbers of units sold and stats provided at Rebreather Forum 3.0 (RF3) by the leading rebreather certifying agencies – represents a tiny percentage of those certified to dive using traditional open-circuit gear; yet, this small niche of divers suffer an extraordinary rate of fatalities.
Simon Mitchell speaking during an earlier symposium in Durham, North Carolina, estimated the five year mortality rate for rebreather owners at 0.5 percent based on the number of rebreather fatalities recorded by Diver’s Alert Network (DAN) around the world that year and assuming 4,500 active rebreather divers.
At RF3, Dr. Andrew Fock, head of hyperbaric medicine at the Alfred Hospital in Melbourne, Australia, said that his best estimate, from all existing data, is that rebreather divers are at ten times the risk of their open-circuit counterparts. In other words, ten times more likely to die when diving a rebreather!
These are sobering stats, and you may have heard – and you may even have repeated – the rather dismissive phrase that “rebreathers are not ready for prime-time.” But this paints the situation with the wrong brush, according to Fock, Mitchell and David Concannon. Rebreathers are not the issue: the biggest contributing factor to rebreather incidents are procedural.
Concannon, a speaker at Rebreather Forum 3.0 and a well-known attorney whose law firm has strong practice in sports and recreation law, sees the issue as a cultural one.
“I am certain that the fix does not require a redesign by mainstream manufacturers or changes in the training [curriculum] offered by established agencies: it’s much more straightforward than that. I believe we need to change the attitude of the average diver preparing for a CCR dive, and this change includes the use of a pre-dive checklist.”
During his law practice and work as advocate for several dive-industry clients (including CCR manufacturer AP Diving and training agency TDI), Concannon has investigated dozens of fatalities. “Striking in its absence in 100 percent of the cases I have seen that involved a rebreather is a physical checklist; no sign of one on the diver’s person, in his kit, on his rebreather.”
This, Concannon says, indicates a “cultural short-coming.”
“When one considers the standard practices in other highly complex environments, such as aviation, medicine or commercial diving, checklists are critical and their use close to universal.” He states that, “Checklists help catch mistakes in equipment setup, set criteria for the dive itself, and help to ensure backups are in place should something go pear-shaped during the dive.”
If it wants to improve diver safety, the rebreather community has to promote and encourage checklist use according to Concannon and, what seemed at RF3, to be the vast majority of experts in the field. “It’s obvious and cannot do any harm,” he says.
Concannon maintains that when a CCR diver is not using a checklist, he or she is the worst diver ever… the exact opposite of the assessment he and his colleagues hear time and time again during their incident investigations, when buddies and relatives state, “He was the world’s best diver, the best I ever saw. His death is a mystery.”
During the past 12 months or so, the diving community and especially many community leaders have begun to voice strong support for the adoption of a checklist mentality. The irony is that several manufacturers produce a unit-specific checklist as part of their user manual, and most instructors promote its use to students during basic programs… and beyond.
“One of the very first tasks students perform,” says Mike Fowler, a CCR instructor-trainer for TDI, “is to create an assembly and pre-dive checklist… a physical list that they will use prior to every dive they do during their course.”
The issue, says Fowler, is that after the course is completed, complacency sets in. “The Vision handset [proprietary to AP Diving’s family of CCRs] displays a series of per-dive checks on-screen,” he says. “But there is no guarantee that the prompts are actually carried out before the user hits the OK key moving the display on to the next step…”
As for CCR divers using the physical list created during their course, Fowler agrees that a cultural change is needed. “We need to tighten up common practices,” he says, “if nothing else, to prevent aborted dives and diver disappointment.”
As Fowler says, many units on the market today have some form of checklist built in, and members of RESA (Rebreather Education and Safety Association) recently discussed the idea of manufacturers etching or printing a checklist on rebreather casings, but several issues remain; there is no guarantee that a diver will use a checklist, and just as importantly, there is no guarantee that, what Concannon calls “inconvenient truths,” will not be ignored.
“Oxygen cells, and specifically the use of cells that are passed their best-before-date, continue to present problems,” he says.
“We may recommend using a voltmeter to check that cell performance is within suggested parameters, and we may suggest changing cells regardless of this test on a regular and conservative schedule, but we still have cases on the books where divers have ignored this advice… and the results can be tragic.”
Human nature is such that there are bound to be those CCR divers who choose to do things their own way, but it seems clear that the best policy to “stay alive” on a rebreather is to stay within the limits of your training and experience, follow conservative best practices, and use a checklist. It’s simple, really.
For more information about checklist, training, and best practices on SCRs and CCRs, contact your local TDI professional.
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