Ginnie Springs diver missing - Florida

[Brad_Horn]

IMO there is little useful to the rebreather diving community at large to be learned from examination of the public record. The coroners job (sometimes called a medical examiner in the US) in these circumstances is usually just to name a cause of death.... typically "drowning" but sometimes if the underlying health condition was the obvious cause (for example heart disease that resulted in MI) then the cause of death will be reported as the medical condition. As one coroner told me, "If there is water in the lungs, they drowned.”

From an equipment perspective this still has to be interesting to rebreather community. Because a cause of ‘drowning’ probably tells you that the unit wasn’t fitted with a gag, crown or mouthpiece retaining strap. That then tells you it either wasn’t CE certified and therefore was almost certainly utterly untested, the strap had been removed (either by the manufacturer, instructor or diver) post CE technical file audit or the unit in question wasn’t tested to the ratified standard of EN14143 in full. Each raising questions about its suitability to follow up on.

Those dying whilst diving with gag straps tending to not be reported as ‘drowning’ based on public records Deep Life Design Team: databases and analysis of rebreather accident data
Also https://www.researchgate.net/public...mong_French_Military_Divers_From_1979_to_2009

The court cases are, surprisingly to many, not about determining a "cause" but rather apportioning liability to those best able to pay. Thus, I've observed parties on both sides of the same case seeming to obscure facts and discredit evidence. One tactic employed by attorneys is to attack the evidence by discrediting the sources, such as the recovery divers and experts advising law enforcement.

Well said.

However considerable value can certainly still be gained by the community in ignoring the resultant liability only focused decision and understanding the implications of the accident analysis (where conducted by experts and published) for the court case or coroners report in question.
Especially where this can be recreated by the reader at home if they have the same gear. Inquest verdict from Jersey Channel islands UK

But I've never found anything that is going to result in an OMG moment where some press release warning divers of a new here-to-fore unknown cause of rebreather deaths. Like open-circuit diving accidents, the causes of closed-circuit diving accidents are now understood. That's not to minimize the loss of life or the investigation in to the accident, but simply to point out that we already have the knowledge to dramatically reduce rebreather accidents.

They might be “understood” by some of the few experts but what is known, and why those causes occur still seems to need considerably better education across the board. A small sample of potential relevant examples to this thread being:
- Scrubber duration Diving a Rebreather in Frigid Water: Canister Concerns
- Current limited cells https://www.apdiving.com/shop/downl...nt_manufacturer_warning_on_cell_limiting.docx
from Coroner’s Report in Phil Gray’s Death Yields Important Lessons | IntoThePlanet
- Water blocked cells https://www.opensafetyglobal.com/Safety_files/DV_O2_cell_study_E4_160415.pdf

No matter how well 'understood', the ratio for the causes, still seems to surprise https://www.facebook.com/OpenSafetyEquipment/photos/a.3505576419471833/3505578606138281/

 

[rjack321]

When experts look at rebreather accidents, we almost always find long (some times amazingly long) error chains that include almost unbelievable lapses in judgement by the victim and typically by many others as well. But I've never found anything that is going to result in an OMG moment where some press release warning divers of a new here-to-fore unknown cause of rebreather deaths. Like open-circuit diving accidents, the causes of closed-circuit diving accidents are now understood.

How about the practice of adding an in-line shutoff to the O2 feed of a mCCR and teaching in MOD1 and cross-overs to breath down the ppO2 (when its a little high like eg 1.4). Compared to the more traditional practice of doing a diluent flush. This is a recent phenomenon, by a large group of instructors across multiple agencies, all teaching the same relatively new mCCR in the same geographic area. New cause? no not really. But its a new practice which only rose to prominence in the last ~5 years.

 

[Kay Dee]

With all due respect, and in all seriousness, when did 1.4 become 'a little high'? I mean how many years has that been considered to be the case, and is that the majority view now?

 

[PfcAJ]

With all due respect, and in all seriousness, when did 1.4 become 'a little high'? I mean how many years has that been considered to be the case, and is that the majority view now?

1.0-1.2 on the bottom/working phase of the dive has been normal for like 20 years.

 

[tbone1004]

With all due respect, and in all seriousness, when did 1.4 become 'a little high'? I mean how many years has that been considered to be the case, and is that the majority view now?

1.3 has been the CCR "standard" for a very long time. As @PfcAJ said in big cave diving the 1.0-1.2 has been "standard" and that translates to CCR's as well. I have only ever seen 1.4 as a MOD recommendation in recreational diving.

 

[bada3003]

Sure. That’s also true in airplane accidents, and other such relatively routine causes of death. And in the case of airline deaths, their safety record is several orders of magnitude greater than scuba.

Not sure where you are getting your data from. Meaningful statistical comparisons are difficult to get and unreliable. In some instances where folks have made an effort, scuba diving is indicated as being safer than general aviation (see chart at the end):

The Risk of Dying Doing What We Love - Soaring - Chess in the Air

Whether that's accurate or not is another matter.

Yet they still conduct detailed root cause analysis. Why? They’re never going to find a new and unique reason...

I can think of at least two reasons: one, sometimes they do. For example, 737 MAX. And for a second reason, that’s how they got their enviable safety record first place, and that’s how they keep it.

They have a decent safety record. The rules instituted after Lithium chemistry battery seemed to self-ignite, issues w.r.t. de-icing, inebriated pilots, and the list goes on. Aviation is not the same as scuba diving.

The biggest difference compared to scuba is the scale of legal liability. When tens or hundreds of people perish, then responsibility has to be assigned. In part to determine what happened so that the risk of repeating the mistake is reduced. Equally, perhaps more importantly, because insurance companies need to identify who the responsible parties are.

 

[rjack321]

With all due respect, and in all seriousness, when did 1.4 become 'a little high'? I mean how many years has that been considered to be the case, and is that the majority view now?

On CCR 1.4 is a little high
1.3 is the default setpoint taught in MOD1

Longer cave dives are much lower, 1.0 or 1.1 is common. At 1.2 you hit 100% CNS in about 4 hours. 1.4 on a CCR cave dive is considered high but not cause for immediate concern. Hence the "just shut off the O2 and breathe it down" instruction, but this is a new phenomenon. Historically, seeing 1.4, would have been reason to dil flush.

 

[John the Pom]

With all due respect, and in all seriousness, when did 1.4 become 'a little high'? I mean how many years has that been considered to be the case, and is that the majority view now?

Isn't tolerance of PPO2 quite a variable and personal thing? One of the guys I learned to dive with was an ex-Navy diver, and they were selected for a high tolerance to PPO2 (they dived with O2 rebreathers at that time). He suffered hypothermia after a problem with his suit and following his recovery from the resulting illness he had an O2 'hit' on his next dive, i.e. his tolerance of PPO2 was suddenly and dramatically reduced.

 

[tbone1004]

Isn't tolerance of PPO2 quite a variable and personal thing? One of the guys I learned to dive with was an ex-Navy diver, and they were selected for a high tolerance to PPO2 (they dived with O2 rebreathers at that time). He suffered hypothermia after a problem with his suit and following his recovery from the resulting illness he had an O2 'hit' on his next dive, i.e. his tolerance of PPO2 was suddenly and dramatically reduced.

is it one you want to experiment with when you do the funky chicken underwater when you find out? The Navy also stopped doing that test for a reason as they concluded that an individuals response to high ppO2 is highly variable. An individuals tolerance to O2 is also very different when immersed vs. dry in a chamber. Duration is also a big factor. Intermittent spurts to 2.0 are very different than 3+ hours.

 

[boulderjohn]

I would like to correct some misinformation in this thread and provide a little more information.

I used to do a lot of rock climbing and mountaineering (in addition to diving) when I was in my 20s/30s. In both sports, it helps to analyze and learn from accidents.

In North America, the American Alpine Club publishes an annual book titled Accidents in North America Climbing.

AAC Publications

(From memory, it used to be titled Accidents in North America Mountaineering)

I used to buy that book every year and analyze all the accidents to see what I could learn. I wonder if something similar exists in our community? If it doesn't, maybe it should?

- brett

the NSS (national speleological society) has a yearly report for dry caving. Underwater caves should have the same. But it’ll never happen.

That NSS report (American Caving Accidents--ACA) includes both dry caving accidents and underwater caves, and it has for many years. I write most of the underwater cave reports. Forrest Wilson has written some as well.

Those reports include North America, Mexico, and the Caribbean.

My report on the Manatee incident last year was done with careful consultation with IUCRR and was adopted by IUCRR as their report.