Error Blue hole fatality

[Nick_Radov]

I don't know the details of this accident (was there a report?) or the procedures for dropping stages in caves, but isn't it more likely to be a lapse in gas verification procedures (complacency?) than for two divers to mistakenly identify the MOD of a bottle at the same time? I might be wrong, of course, but I can see how easy it would be to start getting sloppy with these procedures after hundreds or thousands of gas switches.

I assume you are referring to the death of James "Jim" Miller during a WKPP dive in 2011. I don't know whether there was ever an official incident report but Todd Leonard posted some details shortly after it happened.

Fatality at WKP

Hello, all... I'm Todd Leonard, one of the Project Coordinators for the WKPP, and one of Jim's friends. I've been posting info in the accident analysis thread on the Cave Diver's Forum about Jim's accident Saturday, and it seemed to be helpful there in minimizing the speculation that we...

scubaboard.com

 

[ChrisMBC]

Here's another one that could rile some of the "there is only one good way=my way" folks:

During setup and pre-descent checks, you can pressurize your deco stages, test them, and then re-close the valves to "just a crack open" (to prevent first stage flooding). You will need to reopen these valves to breathe from them. Which you will have plenty of time to do when you reach your deco stops. Below that depth, you can neither tox out on them, nor lose the gas, without spending the time to re-open the valves.

Unless I'm missing something...I thought this was accepted best practice (and GUE SOPs) for deco bottles - dive with the reg pressurized but the valve closed.

 

[justinthedeeps]

@ChrisMBC yes I trained this way as well.

Sorry just been hearing a lot of "why that's pointless" claims this week though on a range of things (BOVs, closing hypoxic gases, blind switch aids, ...)

I wonder if the victim did in fact calmly open up an intentionally closed valve and then breathe from it at depth. That would be odd?

I guess one could mistake it for an add-on hypoxic bottom stage that was also closed as a precaution while shallow. (Which should have been reopened on an appropriate descent check)

Or a "why isn't my deep [sidemount] air tank open already?"

 

[steinbil]

I assume you are referring to the death of James "Jim" Miller during a WKPP dive in 2011. I don't know whether there was ever an official incident report but Todd Leonard posted some details shortly after it happened.

Fatality at WKP

Hello, all... I'm Todd Leonard, one of the Project Coordinators for the WKPP, and one of Jim's friends. I've been posting info in the accident analysis thread on the Cave Diver's Forum about Jim's accident Saturday, and it seemed to be helpful there in minimizing the speculation that we...

scubaboard.com

Thank you for the link. Ultimately it seems to have been a failure to verify the gas switch by the team, as I was hinting at earlier. It reinforces the idea that the gas switch protocol must be followed on every gas switch, no matter how experienced the divers, and it shows how important the human factors are. Even the most experienced and the most meticulous divers of a group known for good protocols and procedures, can fall prey to complacency and normalization of deviance. We can never let our guard down, especially when we get very comfortable.

In my mind it does NOT show that the gas switching protocol is lacking or that you need other "tricks", be it bungees on the mouthpiece or colour coding or what have you, to avoid this problem. A team verification of the gas switch should have prevented the critical error. It just shows the importance of taking the human factors seriously and actively make an effort to counter the very human tendency of complacency.

I'm also guessing that there are, or should be, some protocol for verifying bottles being dropped or picked up, that would have prevented the first error.

 

[Learner Diver]

No diver with any common sense or proper training would ever rely on stage tank location or separation to distinguish between mixes. I have heard of divers coming up with convoluted "solutions" like putting the lower oxygen mix on the left and the higher oxygen mix on the right

I agree, provided you have labelled some kind of readable info on the cylinder.

 

[xan]

I agree, provided you have labelled some kind of readable info on the cylinder.

Yes, that is expected. As one example of a checklist/procedure, posted in #22 above (from the GUE SOP), step 4 is to review the MOD label yourself, and step 11 is for a team mate to review that MOD label as well, and confirm the switch is safe. This takes care of the markings and the switch. (To ensure there's gas matching that MOD label, gas analysis is expected to occur before the dive, cylinders marked etc.)

 

[KevinNM]

Correct. That has been the problem in the majority of cases I have read about over the years.

I’ve seen reports of people trying to breathe 100% O2 in incorrectly labeled tanks to 100% helium in incorrectly labeled tanks.

And one or two where the tank contained exactly what it said but the diver convinced themselves that it had something other than what it was labeled as.

 

[Alex Ouroboros]

As stated by others, at this level the instructor and students should all be checking each other during gas switch, this is to be drummed in to anyone on a tech course,
The vis in blue hole would be perfect for this so if the instructor has succumbed to a compromised gas switch it’s a failure of the entire team unfortunately,
Cylinder markings are precisely for this reason, including one on the neck of the cylinder that the diver can see,
Colour coded regs, bungee on the mouthpiece and all the other ideas while being good for some circumstances are generally flawed, the only guarantee that the diver is on the correct gas is to identify the cylinder that they tested personally before starting the dive, then orienting the regulator you intend to breathe from, one hand then traces down the hose all the way to the first stage to check it is correct, you should always receive some kind of affirmation from a team member watching before then reg switching. As one of my tec instructors used to say “NEVER PUT ANYTHING IN YOUR MOUTH IF YOU DONT KNOW WHAT IT IS!”

 

[steinbil]

one hand then traces down the hose all the way to the first stage to check it is correct

Or purge the reg while looking at the SPG to confirm the reg is hooked up to the bottle you're holding.

 

[Nick_Radov]

Unless I'm missing something...I thought this was accepted best practice (and GUE SOPs) for deco bottles - dive with the reg pressurized but the valve closed.

View attachment 845983

I'm not sure whether this is GUE SOP but at least some instructors have taught an additional action at the end of that list to read the temporary oxygen % analysis sticker attached near the top of the cylinder. This protects against the tiny risk of both you and your teammate misreading the MOD label.

And there are also circumstances (mainly in training) where a cylinder might contain less oxygen than the MOD label would imply. The MOD label merely indicates the maximum depth where the gas is safe to breathe (based on oxygen %, gas density, and equivalent narcotic depth); it doesn't necessarily guarantee that the cylinder contains an optimal oxygen % for your deco plan. Cylinders labeled "70" (ft) MOD sometimes get filled with something like 21% or 32% instead of 50% just to practice gas switching and bottle rotations. If you accidentally bring one of those on a real tech dive then you won't tox but you might end up in the chamber.