When In Doubt, Bailout
In a rebreather accident, many quickly assume a fault on the part of the equipment. Yet, if we go back in history, we'll see that this isn't the first time we removed responsibility from the diver. In most cases, user error is the issue and we should all remember to keep our safety protocols in focus.by Lamar Hires
Read the headlines, when a person dies on a rebreather the first thought that's voiced is what happened to the rebreather. It has to be a problem with the rebreather. Why is user error/choice not the first thought? We are not immortal and mistakes are made.
I need to go back in history to set the stage for my thoughts. Thirty years ago every time we had a fatality in a cave it was the cave's fault. Landowners wanted to close the sites because they knew the caves were dangerous. We started a massive campaign to educate the public, divers and training agencies. We got our point across, open water agencies started promoting and teaching cavern diving. We got past the killer cave phenomenon and people starting started asking did the poor guy not follow a guide line or reserve enough air for the exit.
Twenty years ago nitrox and trimix evolved and we battled voodoo gas and everyone was going to die if they used it. Like cave diving there were many fatalities as we learned our limits and gained respect for the new found knowledge. The rules were simple but people didn't believe they could be a victim and there should be a lot of forgiveness in the rules. They were wrong and we finally educated the public. It was no longer voodoo gas; gas switches and user error were accepted as that.
Today the new bad guy is rebreathers. When someone dies on a rebreather it is immediately a problem with the rebreather. The diver could not make a mistake; he was a good open water diver. I hate to disappoint you but this was the same conclusion for cave and technical fatalities but we soon learned that operator choice/error is the dominant factor.
The primary focus of rebreather training is bailout whenever there is a problem. Always know your PO2 and monitor the systems every 2 to 4 minutes (check training agency for specifics). Primary displays, secondary and heads up display create redundancy in control and monitoring systems. The diver must monitor these and at the first sign of concern bailout.
So the first question in a forensic analysis should be why didn't the diver bailout? Did he start with a system error? If so, why? You should never start a dive with a known failure, when discovered the diver should bailout, with frequent monitoring, every 2 to 4 minutes, electronics failures are easy to deal with, bailout. Since no electronic failure results in instant death, did the diver not pay attention to his instrumentation or ignore warnings? The key here is diver awareness, back to user error/choice. There are very few conditions that can happen without warning via the electronics monitoring systems; hypercapnia is the primary condition while high and low oxygen conditions are monitored via electronics.
I liken rebreather divers to pilots, it's no wonder we call it flying the rebreather. The difference is pilots have to maintain flight hours, routine flight physicals and renew their license. Rebreather divers don't need to do any of the above and they can also work on/and or modify their rebreathers without any training or certification for the work. Their rebreathers aren’t required to have annual inspection or maintenance to fly. So the primary educational piece should be bailout and the question should be asked “why didn’t he bailout”.
Maybe this is a training issue. We teach divers all the options to stay on a rebreather at technical level training. How to fly manually and semi closed. We teach them how forgiving the rebreather can be in the first 500 minutes of diving exposure to a rebreather. Maybe we should teach only one solution for any problem is bailout and don’t look at any other options until the diver has another 50 hours on the rebreather.
With any accident the first question should be ”Why didn’t he bailout?” then the accident analysis is based on this one simple question. Divers should maintain hours and proficiency on their units just like pilots.