Fiona Sharp death in Bonaire

[lermontov]

But we do have enlightening discussions, and I learn a lot here. And the mods do yeoman's work to keep things on track, weed out inappropriate comments and (in cases like the Conception tragedy), maintain a running summary of what is known to date.

Maybe we look at it from different parts of our personality make up - one side struggling with the loss and trying to come to terms with a lost fellow diver from an emotional perspective, and see the questions and queries as repulsive and intrusive.
Another type also struggling with the loss but coming to grips with it by trying to make sense of it all by analysis so that it can be 'pigeonholed' and maybe then emotionally come to terms with it. Our brains have a habit of wanting incomplete puzzles to be sorted and understood- it makes US feel better
Or maybe some sort of anxiety or self preservation wanting to know what happened to make sure I don't fall victim to the same mistake or misunderstanding.

As selfish as it may seem I want to know for my sake, I want to know how an experienced ccr diver died so i dont, and maybe i can warn others - I think that's a good enough reason

 

[runsongas]

@doctormike has there been a documented study on loss of consciousness recovery while ccr diving with FFM?

 

[chillyinCanada]

Maybe we look at it from different parts of our personality make up - one side struggling with the loss and trying to come to terms with a lost fellow diver from an emotional perspective, and see the questions and queries as repulsive and intrusive.
Another type also struggling with the loss but coming to grips with it by trying to make sense of it all by analysis so that it can be 'pigeonholed' and maybe then emotionally come to terms with it. Our brains have a habit of wanting incomplete puzzles to be sorted and understood- it makes US feel better
Or maybe some sort of anxiety or self preservation wanting to know what happened to make sure I don't fall victim to the same mistake or misunderstanding.

As selfish as it may seem I want to know for my sake, I want to know how an experienced ccr diver died so i dont, and maybe i can warn others - I think that's a good enough reason

And in the course of the conversations, we often discover other points that may save us, that had nothing to do with the accident that we were discussing at the time.

May I point anyone reading/participating in this thread, that isn't familiar with the terms of service, to the header stickie posts for the Accidents and Incidents subforum.

 

[doctormike]

@doctormike has there been a documented study on loss of consciousness recovery while ccr diving with FFM?

You mean a case report? Have never seen one, but I would assume that the same sort of rescues that were done in the French military study would be just as possible with a FFM.

When you say "recovery", do you mean spontaneous return of consciousness or a rescue by a buddy? I have heard of people falling asleep with FFM or gag straps, so I guess that counts...

 

[CuzzA]

Except for the last sentence.

Ahh, pretty close when combining OC and CC. But I cede your point. You just gotta have a buddy and be wearing the strap.

 

[doctormike]

Ahh, pretty close when combining OC and CC. But I cede your point. You just gotta have a buddy and be wearing the strap.

Yeah, I keep going back and forth about this. I think that if I did use a gag strap, I would want a BOV, because I would be concerned about switching mouthpieces in a hypercapnea panic with a gag strap in place. Basically, I'm very impressed with the engineering and thoughtful attention to detail in the design of my rebreather, so the fact that they don't recommend a BOV or a gag strap means something to me...

Starting to drift off topic, so I'll leave it at that.

 

[Dan]

Interesting paper:
Analysis of recreational closed-circuit rebreather deaths 1998–2010
by Andrew W Fock
https://www.divegearexpress.com/pub/media/Documents/miscellaneous/Fock-Rebreather_deaths.pdf
Diving and Hyperbaric Medicine Volume 43 No. 2 June 2013, pp. 78-84.

"The 181 recorded recreational rebreather deaths occurred at about 10 times the rate of deaths amongst open-circuit recreational scuba divers. No particular brand or type of rebreather was over-represented. Closed-circuit rebreathers have a 25-fold increased risk of component failure compared to a manifolded twin-cylinder open-circuit system. This risk can be offset by carrying a redundant ‘bailout’ system. Two-thirds of fatal dives were associated with a high-risk dive or high-risk behaviour. There are multiple points in the human-machine interface (HMI) during the use of rebreathers that can result in errors that may lead to a fatality."

According to Table 1, #1 CCR fatality during 1998-2010 period is due to hypoxia.

 

[runsongas]

You mean a case report? Have never seen one, but I would assume that the same sort of rescues that were done in the French military study would be just as possible with a FFM.

When you say "recovery", do you mean spontaneous return of consciousness or a rescue by a buddy? I have heard of people falling asleep with FFM or gag straps, so I guess that counts...

spontaneous return of consciousness without direct buddy aid.

 

[doctormike]

spontaneous return of consciousness without direct buddy aid.

Unless you are talking about just falling asleep, I haven't heard of that.

Losing consciousness on a rebreather would likely be from hypoxia or hyperoxia (hypercapnea can also cause LOC, but would probably with more of a prodrome). So if nothing changes with the loop contents, not sure why you would spontaneously regain consciousness.

 

[fsardone]

Hmm, perhaps on the desktop but probably not in the water. Descending that fast I would have to keep adding hot dil (at least after the first 60 meters or so) to make up volume to keep the loop breathable and I doubt the PO2 would breathe down significantly in the time allowed by this table. My intuition, based on a lot of ultra rapid descents on CCR, tells me that for my physiology it would be almost impossible to make a "quick bounce" to 90 m using air diluent without a PO2 spike to around 2 ata while also doing a significant amount of work. Just pointing out this bit of speculation is questionable on the face of it; not making any observations about the accident as I don't know anything at all about it.

Concur,
I do not have much experience in doing something it should not be done. I was barely calculating if you could think that 2 s40 would provide enough gas to bail out and surface based on deco profile.