Waterford Garda dead - County Wexford, Ireland

[helodriver87]

No. My point was that there can be NO rebreather failure but the succession of errors by the diver may lead to the diver toxing. I know at least one close and personal example.
Our Irish friend doesn't seen to believe that this is possible. I would invite him to open up his mind to the endless subtleties of human psychology...
I also pointed out that you can die of oxtox on OC if you breath the wrong gas at the wrong depth and there again, everything might otherwise work just fine, but use error will result in death. This has happened not so long ago, when a diver declined to analyze his gas before a cave dive and toxed out.

Well, my primary point was in regards to proximal cause. But yeah, it's entirely possible this was fully self induced. Without further information it's hard to say for sure. The only conclusion I'm comfortable drawing right now is that human error almost certainly played a meaningful part, and only because we know PO2 information and warnings were displayed on the handset

 

[Colliam7]

No. My point was that there can be NO rebreather failure but the succession of errors by the diver may lead to the diver toxing.

I don't think you and I are really in substantial disagreement. By using the phrase 'may be technological failure', I was trying to be inclusive of a variety of starting points in the accident cascade. I agree with you - there are more than a few documented adverse outcomes where there was no failure of technology / equipment, and user error by itself - one, or the more common chain of errors - led the diver(s) to grief.

Our Irish friend doesn't seen to believe that this is possible. I would invite him to open up his mind to the endless subtleties of human psychology...

And, I would as well. There is a continuum of assignment of responsibility, aka 'blame'. Some see only the end where human beings are blamed for everything - we have pilot error, diver error, whatever. They may see this as some kind of conspiratorial cover-up of manufacturing / industrial / technological failure. Others see only the opposite end of the continuum, where technology - machines - are blamed for everything and human beings are victims, and they see a conspiratorial cover-up of human error. Well, I see a contribution of both, depending on the situation, but I tend to lean to human factors more often as a root cause. Was the Challenger explosion a failure of equipment, or human error? Well, quite obviously, the explosion that led to the break-up of the craft was equipment failure - the infamous O-rings. But, what was the error that put the craft in the position for the O-rings to fail. I think the subsequent investigation made clear the series of errors in judgement, occurring over an extended period of time, was the cause.

This has happened not so long ago, when a diver declined to analyze his gas before a cave dive and toxed out.

And. that particular case - presuming that I am thinking of the same one - was an especially egregious example of user error, where he failed to follow the most fundamental, established procedure of analyzing his own gas, relying instead on (what turned out to be) flawed memory of what was in the cylinders. The whole reason we have checklists is to prevent failed recollection from bringing us to harm. Yet, that diver was sure that he recalled what was in the cylinders, and he was completely wrong.

 

[Celt]

I think that the point that posters are making is that there may be technological failure, but the proximal cause of ultimate outcome may nonetheless be user error.

There may be failure of technology, but users can still react and salvage the situation. Several posters have made reference to aviation, such as comments on how prominent the sound of a stall horn is. Yet, even though stall warnings are prominent, pilots still mange to stall airplanes.

One extraordinary example of the relationship between user error and equipment failure, in which equipment failure was the initial problem, but user error was the proximal cause of the tragic outcome, was Air France 447. The equipment failure was pitot tube icing. As a result, the pilots lost airspeed information, and the autopilot turned off. Notwithstanding that issue, the aircraft was still very flyable - it remained entirely airworthy - the control surfaces were fully functional, the engines remained capable of producing full thrust. But, the pilot flying the aircraft (right seater) stalled the aircraft, by gradually pulling back on the yoke, probably out of anxiety, perhaps complicated by distraction. According to the investigative reports, the stall warning sounded prominently some 75 times over the next 4+ minutes, as the pilots literally flew the aircraft into the ocean. The proximal cause of the accident was user error, not equipment failure.

And the only reason you can make the argument referencing aircraft is there’s comprehensive investigation into aircraft accidents, there’s little or no investigation when it comes to rebreathers and no date is released or published and the reason is too many people accepting the excuse that the cause is user error. What other manufacturer can blame the user when their equipment fails and the reason they give is they failed to switch to a complete different system which has nothing to do with their system. If the results weren’t so tragic it would be laughable.

 

[Celt]

No. My point was that there can be NO rebreather failure but the succession of errors by the diver may lead to the diver toxing. I know at least one close and personal example.
Our Irish friend doesn't seen to believe that this is possible. I would invite him to open up his mind to the endless subtleties of human psychology...
I also pointed out that you can die of oxtox on OC if you breath the wrong gas at the wrong depth and there again, everything might otherwise work just fine, but use error will result in death. This has happened not so long ago, when a diver declined to analyze his gas before a cave dive and toxed out.

What you’re attempting to do is muddy the water with totally different scenarios than what really happened in the case which this tread is about, well you’re right I won’t engage with your hypothetical arguments.

 

[Celt]

News flash, if you don't react quickly enough to most breathing system failures underwater, you'll die. And I'll reiterate it One. Last. Time. Toxing isn't instantaneous. He likely had a few minutes to recognize the issue and take a two second corrective action.

If something doesn’t make sense then it can’t be true. It doesn’t make sense that if he had time to prevent his death that he did nothing. He didn’t get the bailout reg into his mouth, it could be done in seconds.

 

[helodriver87]

Ok. This is beyond pointless and you're actively being difficult at this point, so I'm going to stop responding to you. The fact that you think it's impossible for an experienced diver to make a mistake and fail to respond correctly to a failure is honestly astounding. I don't even know how to have a discussion on accident analysis with someone coming from that position, which is why this discussion is continually circling back on itself.

To anyone actually looking to understand the possibilities here, you can safely ignore mac's posts. He doesn't understand rebreathers or human factors and it's glaringly obvious. I'll happily continue the discussion with anyone else at this point or let it go.

 

[Dan]

From https://www.scubadivermag.com/irish...cSudL7xlROoqCeuAdIG-cxsTJ5eBGm0MJscE4hsgsKa_M

"UK-based technical instructor Dave Gration examined Mr Hearne’s CCR, and found that a number of alarms had gone off to signal a spike in oxygen levels. Mr O’Herlihy said: “Something went wrong down below and it appears to have been a spike in oxygen, for whatever reason. It seems that the late Mr Hearne was not able to deal with that spike, it had caused him to go into a convulsion, the mouthpiece went out of his mouth.”"

It seems to me that human error plays apart in this accident. Wouldn't experienced diver would switch straight to Bailout bottle in fear of oxygen toxicity at depth instead of wasting seconds trying to deal with the oxygen spike?

 

[helodriver87]

From https://www.scubadivermag.com/irish...cSudL7xlROoqCeuAdIG-cxsTJ5eBGm0MJscE4hsgsKa_M

"UK-based technical instructor Dave Gration examined Mr Hearne’s CCR, and found that a number of alarms had gone off to signal a spike in oxygen levels. Mr O’Herlihy said: “Something went wrong down below and it appears to have been a spike in oxygen, for whatever reason. It seems that the late Mr Hearne was not able to deal with that spike, it had caused him to go into a convulsion, the mouthpiece went out of his mouth.”"

It seems to me that human error plays apart in this accident. Wouldn't experienced diver would switch straight to Bailout bottle in fear of oxygen toxicity at depth instead of wasting seconds trying to deal with the oxygen spike?

There are a couple of ways this can occur. One is simply high PO2. This can happen because of a fast descent, running out of dil, accidentally adding O2 on descent instead of dil, or a slow leak into the breathing circuit (I'm sure there are other ways, these are just examples). The other way is runaway O2. This will result in rapidly climbing O2 and constant O2 addition. You'll also feel a buoyancy shift. This can be a stuck solenoid, sensor problem/voting logic failure, or stuck MAV (on JJ). In both cases, you want to get off the loop ASAP when you see PO2 go to unsafe levels. Difference is with runaway O2, you want to keep the loop in your mouth and let the gas escape around your lips while you shut off O2. Then switch to bailout. This prevents a flood since it's still in your mouth, prevents a major buoyancy shift since you're letting gas escape, and prevents toxing since you're not breathing the hyperoxic gas. With regular high PO2, just get off the loop and onto bailout. Then in both cases you start analyzing the cause. Or just bailout and be done with it.

But yes, ultimately, there's zero reason to continue to breathe hyperoxic gas once you recognize the condition. It seems likely that he either didn't recognize the issue or incorrectly responded to it. You're not going to seize the second that hot mix hits your lungs.

 

[Celt]

From https://www.scubadivermag.com/irish...cSudL7xlROoqCeuAdIG-cxsTJ5eBGm0MJscE4hsgsKa_M

"UK-based technical instructor Dave Gration examined Mr Hearne’s CCR, and found that a number of alarms had gone off to signal a spike in oxygen levels. Mr O’Herlihy said: “Something went wrong down below and it appears to have been a spike in oxygen, for whatever reason. It seems that the late Mr Hearne was not able to deal with that spike, it had caused him to go into a convulsion, the mouthpiece went out of his mouth.”"

It seems to me that human error plays apart in this accident. Wouldn't experienced diver would switch straight to Bailout bottle in fear of oxygen toxicity at depth instead of wasting seconds trying to deal with the oxygen spike?

He didn’t get a chance to bailout, the obvious answer is usually the correct one.
P.s. with all due respect to Dave Gration he,s an instructor not an engineer, That gear should have been seized on the surface and inspected by an independent group of experts, instead of “oh hey lads does anyone know who could have a look at that gear we’re going to need a report for the autopsy? yeah I know a guy! happy days. There is no independent marine investigation in Ireland

 

[Jack Hammer]

Number One rule of rebreather diving . . .

ALWAYS know your PO2.