A thought experiment concerning “team bailout” when diving CCR in a cave…


LongO'THREE

First off: Can anyone explain the rationale behind “Team Bailout?”

Hang on… that needs to be rephrased.

Let’s start with this: Is it just me or is the concept of “Team Bailout” for CCR Cave Diving just bat-shit crazy?

Yea, that’s way closer to what I was thinking…

Ok, for those of you who may not be familiar with the team bailout concept, it suggests that a buddy team diving CCRs in a cave environment – you know, wet rocks, hard limestone overhead, perhaps an hour or more from the surface – that they carry sufficient bailout gas “…to get one team member back to fresh air from the point of furthest penetration.”

In certain circumstances, this approach may sufficiently protect team members from harm, but those circumstances should not include the category of diving the vast majority of us engage in.  I believe, a better, more satisfactory practice is for EACH diver to carry MORE gas than is required to get themselves back to fresh air from the point of furthest penetration.

The arguments I’ve heard against using this more conservative tactic is: 1) carrying multiple bailout cylinders is a pain; 2) the likelihood of more than one CCR failure among a team is too slight to consider; 3) calculations for the volume of gas required in a high-stress situation adhere to a well-defined formula corrected for all variables, and therefore it is possible to calculate with a degree of accuracy sufficient to be safe.

Experience is a better guide to best practice behavior than deductive logic, and I have limited experience in this area. So, perhaps my paranoia is unjustified; but here’s a scenario we might all give some thought to before our next cave dive.

Here goes:
Three CCR divers were in the back of a low-flow cave. Each carried an aluminum 40 filled to capacity, which lumped together was enough gas to get any one of them out of the cave and back to dry land. Even at double their normal consumption rate, this was the case. Their dive was well within the parameters of team bailout therefore.

At the worst possible time, Diver A’s CCR went belly up. He could not revive it in any way, and has to bailout. The team began its swim out. A little sooner than expected, but still more than one-third of the way out, Diver A’s bailout cylinder was empty, and he asked Diver B for her cylinder. She suddenly realized that by giving it up, she will have no contingency gas herself. The surface was still a good swim away. Very reluctantly, she handed over her bottle. Momentarily distracted by her thoughts, she floated to the cave’s ceiling and took a minute to recover, which held the team’s progress to the surface still further. Stress levels in all three team members was now peaking. None of them was comfortable.

They were in fact, more small failure, one additional glitch away from a total melt-down. A surprisingly short while later, Diver A – who had been thinking for the past several minutes, what would happen if he got a bottle with a dodgy regulator or had a free-flow, and whose respiration rate had understandably elevated – once again was down to seeds and stems. This time in his second bailout. He turned to Diver C. Diver C had been thinking about this hand-off for a while. He was VERY uncomfortable donating his gas… however, he did so. Several minutes later, the team arrived in the cavern area. Diver A had barely sufficient gas to conduct a safety stop, but did so. Just as the team left the overhead, his regulator began to breath very, very hard.

On shore, while shucking their gear, the group was uncharacteristically silent, each with their own thoughts. What do you think the outcome of this incident was:

  1. This group did not cave dive together ever again
  2. This group rethought their bailout strategy
  3. This group  continued to dive team bailout

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6 thoughts on “A thought experiment concerning “team bailout” when diving CCR in a cave…

  1. I’d hope that they’d rethink their bailout strategy. I’m not a rebreather diver; just a run of the mill open circuit cave diver, but “team bailout” makes no sense to me. Every diver on a team should be self-sufficient, including having immediate personal access to twice as much OC gas as is needed to exit from the farthest point of penetration. A variety of things could prevent a diver with a dead rebreather from gaining access to OC gas that is somewhere other than on his or her person: team separation, lost buddy, low or zero visibility, a dropped tank, and OC free-flow, a bad regulator, a team member who loses composure and bolts for the exit, etc. Those are just the ones that immediately occur to me; I’m sure that there are many more.

    Mike

  2. Steve, when I have heard the term ‘Team Bailout’ it has been that everyone has their own immediate ‘bottom’ bailout to resolve the situation and then there has been enough deco gas to share between the team e.g. each diver would carry bottom bailout and either a 50% or 100% bottle (team of three likely 2 x 50% and 1 x 100%) because of the chances of two CCRs having a catastrophic failure are pretty slim. Further, it depends on your view of a team member being lost (separated) and whether that is considered a critical failure. So to me, the first part of the thought experiment is to define ‘Team bailout’ and its construct and use. For a single bailout cylinder, it doesn’t make sense.

    In terms of the what happened after this dive, it all depends on how much they talked about or debriefed the dive and where they individually thought the issues lay. Each answer is perfectly valid.

    “Safety is not the absence of accidents or incidents, but rather the presence of defences and the ability to fail safely.” – divers need to consider multiple failures in their plan. At some point, the failures will mean that you can’t conduct the dive ‘safely’ and it then becomes a ‘risky’ dive whereby the benefits will outweigh the risks. However, this normally happens at expedition / exploratory level diving.

    • Yes, Gareth: it would have been best to fully define the term in the introduction. In fact the practice that triggered my writing was one discussed with Becky Kagan Schott waiting for a plane at Calgary airport… CCR divers each carrying a 40 cubic foot / five litre aluminum cylinder and swimming well beyond the Maple Leaf and as far as the First Stage Bottle Rock at Ginnie Springs.

      • Steve, I put this down to a lack of understanding about how/why the ‘rules’ are in place. I recently was made aware of an incident in which two divers were on a KISS GEM and a HOLLIS Explorer on a 35m dive and one of them ran out of gas and went to an OC colleague of mine; neither had bailout. During the subsequent discussion, it appeared that neither diver had a bailout because “they thought that bailout was only needed for O2 spikes” – as both were Nitrox gas-extending rebreathers, they did not consider them relevant…

        So, in the case you cite my first question would be, had they consciously made the decision to use team bailout in case of an emergency, had they worked through the numbers, and finally, had they done this before and nothing adverse had happened in the past?

        We’ve talked of the normalisation of deviance plenty of times – it is natural…! It takes strong leadership and communication skills to say ‘No’ though.

  3. A while ago I have visited Tom Mount and we have discussed the teambailout rule. Als there is written ‘each team must carry enough bailout to get 1.5 diver to the surface’. He said they have tested it several times and that is really enough. But of course there are things to think about. Every diver needs to have a bottomgas. Teambailout and you have to find a teammate who carries the bottomgas is completely bullshit and should never be done. For myself I prefer to have my own bailout. But if you choose for teambailout, in Dopplers example are some things written that never should happen. Bailing out must be a skill that is ‘normal’. So plopping to the ceiling is not done when you swap cylinders around, that means your skill level is too low. That is the first part.
    Then second, ali40’s as bailout (1 per person) are only good for open water on shallow dives. I take in caves at least 1 ali80 as gasamount. Or if you want to be redundant: 2 cylinders (2 times ali40, or 2 ali80’s, depends on what you think is best or what you have). For more demanding dives with deco you take oxygen and decogases too (drop them at a good place).

    In a real bailout situation there is 1 thing that can be really tricky: a real CO2 hit. The first minutes your consumption is high, extremely high, and are you able to go from loop to bailout? How long will it take to solve the CO2 problem once on oc? Going back to the loop is never an option with a CO2 hit. It is important to practice this skill from cc to oc often. Always know where the main oc regulator is, don’t hesitate.

    But if you have just another smaller problem (p)scr bailout can be an option. CCR gives you more time to solve problems in some cases. It is not only bad diving a ccr, as some divers think.
    It is just practise and repeat skills so they are normal. 1 buddy had on 1 dive 600m in the Cabouy cave in France a 2 cell failure and bailed out. The consumption was low, and 1 ali 80 was enough to go back to surface. Reason of no problems: know what to do, a cell failure is not a disaster you cannot handle. So know your ccr and practise the skills.

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