Comprehensive list of all accidents

Freef

Thanks for the answer that you have the Dolphin WOB figures.

How do Rebreather WOB's compare with OC? And why is semiclosed higher? Because of the continual flow of gas and the effort to open the dump valve, or is there someting in the design?

Personally I find the Dolph easier to breathe than OC, but I have been diving for 10 years adn can't remember if I noticed the extra effort in breathing OC when I learned to dive anyway.

__________________
David.

Currently owner of two differently sized ankles.

Gill Envy

Actually I don’t agree completely Andy, though I certainly understand this type of sentiment.

The disparity in numbers of units in use likely accounts for some of the disparity in numbers of fatalities, but not all and likely not the bulk ,IMHO, given what I have experienced in the last year and what i've been studying. Of course the disparity in "%" vs "numbers" of fatalities are two very different things, the % is the key. The margin for error in a smaller sample group is higher and that also needs to be taken into account, but there is a growing likelihood that it does not account for the bulk of the difference, IMHO. Because of the nature of rebreather accidents and the way much of the evidence is lost before the fatality is even known about and because of the staggering number of variables involved, a growing number of divers are not satisfied with waiting around for conclusive evidence that may never come. My irritation with the "idiot" comment of Alex's stems from that. these people are certainly not idiots and my comment about WOB was really a miss placed side track. It just may be that even though analyzing the accidents, promoting more stringent testing and rigerous certification requirements can be a good thing, that it's not going to slow down the accident rates on eCCR's, because more exacting technology may not be the true cause or the true cure for the 1% who have fallen. I suggest that the number one cause is the way that design influences tendencies in behavior patterns, some of which are not voluntary. I realize that that is a big jump, but it bears serious consideration, IMHO.

The sample group of mCCR divers is small, but expanding exponentially. If Alex is right and there are 3 fatalities out of the 600 mCCR's in use, and two are on home builds and one involved entrapment and ended as an out of gas open circuit fatality then the difference could actually be even more dramatic than it currently appears. I'd be amazed at this point if the tendency is a coincidence, though there are tempting ways to explain it away and there are certainly a plethora of gray areas to get hung up on. Even if we let Alex's estimation stand of 3 fatalities/600 mCCR vs 150 fatalities/10,000 eCCR's (.5% to 1.5%) that is still a huge difference. If mCCR fatalities are actually closer to zero, then the % difference may even turn out to be closer to, maybe even better than, OC fatality rates. either way, I think it would be a mistake to ignore the phenomenon.

Depending on how you look at it, the difference in risk is looking like it could be on the order of hundreds of times greater on eCCR’s (mind you even 1.5 % on eCCR's is not a death sentence, but still staggeringly high). If this turns out to be true, it does not mean the end of eCCR's... there are legitimate reasons to dive them, even if it's just that you like the convencience, but identifying and acknowledging the added risk may be key to finding a way to compensate for the human element of the risk. If the greater risk is taken on knowingly, that alone may go a long way to lowering the accident rate. And it may also be worth each individual asking weather they really need the convenience of auto injection and more seriously considering if a manual system would meet their needs and wants.

The irony is that manual systems appear more dangerous on first glance. You'd expect the numbers to be reversed. I'm the first to admit that on face value, this hypothesis is counter intuitive, which is why i keep going on and on about it... it took me a long time and a series of unlikely circumstances to give it such a hard look.

I realize there are lots of "if's" "and" "or" "buts" in what i'm saying and it's not my preference to make such leaps in logic and such pressing proclaimations without more solid evidence but I question if we are ever going to find the kind of hard objective evidence we all want, at least not soon enough... sadly it seems the bell continues to toll every couple of weeks.

Comparing the global numbers of fatalities for mCCR with the global numbers for eCCR is problematic, I agree, but there is precedent for this kind of scenario in research. If 1.5% of users in a drug study were dying for unknown reasons, no one would wait around to find out why before ending the study. I"m not suggesting everyone stop using eCCR's, but when you can not nail down exact cause and effect parameters (too many variables, small sample groups, too high a risk, etc) global outcome numbers are your next best source of data to look at for probable couse… where it’s problematic is that outcome study points to a result but not to a specific cause. As has been pointed out before mCCR’s could be self selecting a group of users with unique behavior patterns (more anal), maybe there are used for less demanding dives, maybe people dive them more conservatively and maybe they instill certain tendencies in the diver, perhaps all of the above. Sometimes determining the reason is deemed less important than identifying the outcome, particularly when lives are at stake. At this point we are left with outcome numbers and supposition and I admit that is a sad state of affairs, but it does point us in a direction that seems to have some revealing potential.

I’m not so worried about a reverse trend happening where a bunch of complacent lemming divers get attracted to mCCR’s and start dropping like flies. I would contend that if you take even the most lackadaisical recreational diver and put them through mCCR training that they will either run for their lives, fail the course or rise the the occasion by developing the the necessary habits. I would content that those who make it through a reasonably rigerous training course would be less likely to have a fatal accident on an mCCR than an eCCR because the “mCCR safety system” (or lack there of) is self reinforcing… the student never leaves the classroom! the study of influences to po2 fluctuation becomes an ongoing study. The individual never gets the impression the system is going to take care of them! Every step of every dive instills learning and awareness, at least that's what i've found. From my personal experience, this changes the core modus operandi and in turn influences every step of preparation and every step of the dive, it appears to have an across the board impact on attitude and habit. If i was not experiencing this personally in my transition from e to mCCR, I would not be so convinced of it's apparent validity.

Everyone is correct in saying that the reason for the current disparity in fatalities is yet known but the outcome is becoming harder to argue as the number of mCCR users is increasing exponentially without a change in fatality rate. To more and more folks, this outcome is enough to be actionable.

The possibility that the lack of fatalities on mCCR's is not a coincidence deserves at least as much analysis as is going into the fatalities on eCCR's and may prove very fruitful in preventing deaths even on eCCR's.

Is anyone with a degree in behavioral sciences studying the cause of fatalities along side the engineers?

I think the rebreather for the masses is a manual system, at the very least for the avid recreational diver (the largest untapped market) and when word really gets out, the ratio will become more like 10,000 eCCR to 100,000 mCCR divers... there is a huge market on the verge of blossoming, IMHO, if a system (diver and style of rebreather) can be identified which more consistently results in survivability than the current eCCR market... manual injection systems look to me like they fit the bill.

I"m going to give this a break for a while... it just may be that only time will give us a more solid answer.


"The greatest friend of truth is time, her greatest enemy is prejudice, and her constant companion is humility."

Charles Caleb Cotton

__________________
Gill Envy

...Because I wasn't born with gills!
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Freef

I agree in part with Gill Envy's opinion of mCCR vs eCCR, but surely for recreational divers [40m/no deco according to PADI, some deco according to others] SCR would be better?

mCCR relies on the diver being in control at all times, and I think attracts a more disciplined diver than the average eCCR diver. eCCR allows people to relax and enjoy the dive as they would on OC, and after a while forget to monitor the handsets as often as they should.

People get lazy unless prodded. Just think of how many people have run out of petrol in their cars despite a fully functional petrol gauge.

__________________
David.

Currently owner of two differently sized ankles.

tinybubbles

Great question about WOB on OC vs CCR. We've all over breathed OC and swam away with only a headache.

And isn't it SOP to teach eCCR students to fly manual? Seems like only the more anal divers I've met rely on the e. It's like jumping without a reserve.

Great thread, a little verbose, but great input for someone who doesn't want to join the 1% anytime soon.

silent running

Hi Gill, while I agree that the disparity in M and ECCR accidents may ALSO have SOMETHING to do with the different kinds of behavior required to operate them, IMHO, the difference in numbers of units is too great to ignore and is the obvious factor we must consider first. And because of all the inconclusive and or incomplete accident reporting, it's not easy to get far beyond that fact.

While most of us are familiar with the various design flaws of the ECCRs on the market and all the room for improvement, painting all ECCR diver behavior with the same complacency/behavior brush is too broad for me. IMHO, there are enough differences btw the designs, training and uses of the various ECCRs as to make generalizations about ECCR diver behavior difficult, beyond all relying on the use of a solenoid to replenish O2. -Andy

AD_ward9

We are certain about the numbers of units sold and in use, within a margin of 10%, that we have published previously. We are not allowed to publish them on Rebreather World, but many on here will have noted them down.

These numbers mean that we should have seen 6 accidents on KISS mCCRs but we have seen none. The numbers mean we should have seen 1 accident on other mCCRs but we have 3 recorded.

These are not strong statistics, but there is a tendency. For example, by the time Megs had equalled the sales of KISS (Sports and Classic) units, there had been 9 fatal accidents and some serious incident reports. For the Inspo, the numbers were higher still for those early units.

Many KISS mCCR divers are not trained on the unit. The current fascination with plastic cards and getting trained for every little variant to equipment is comical in this context. Early KISS units were sold as kits to people who knew how to dive, with no training on the unit. Looking down the accident list, one could even claim that training courses are dangerous: accidents and serious incidents with divers in training. Now people usually go on a course, so manufacturers get away with selling rebreathers with no trim (assuming instructors will sort it out), putting divers into a seahorse position and inviting them to put cam bands onto weights which get fixed to tanks ... When I test a rebreather I will always test it in the form it left the factory, and I have nice collection of videos and photos of the result. There is a sloppyness here, that comes from getting instructors to fix equipment design issues, that the KISS avoided by its sales methods in the early years.

The mCCR philosophy that has been more recently reinforced by training, does appear to be good at getting the diver to become one with the equipment, so the divers knows what the PPO2 should be before looking at the displays, and is emotionally programmed to look. Looking on entry, during the surface swim, start of descent, mid descent, end descent, during ascent looking continuously etc, or whatever. Result: no hypoxia accidents on KISS mCCRs to date, despite the orifice having a risk of blocking as it is just a single hole.

There are two other types of accident that stand out on the list: WOB failures and scrubber failures.

WOB accidents involve divers too deep, often in current etc. The principle of constant mass flow keeps the mCCR diver to under 80m anyway, and it is probably only that and the BOV that has avoided accidents because KISS mCCRs have more than double the maximum permitted WOB in EN14143:2003 or under NEDU recommendations.

Scrubber accidents: perhaps knowing their metabolism makes mCCR divers more aware of their breathing rate? Too low a number to understand is it a coincidence or true that mCCR divers are more careful with scrubber changes and scrubber life.

As I said at the beginning, mCCR appears safer for now, but stats to understand what factors are involved are thin. I feel a complacency developing about mCCR: the safety weaknesses those units have should be addressed, and only then can we all be sure of the quality of any comparisons. Despite that comment, good mCCR does appear to be a better way to go for most sports divers than to eCCR.

Meanwhile to Freef's point - he is right: SCR stats are excellent! More Dolphin and Ray SCRs alone were sold than all eCCRs put together. Most home builds are SCR as well, but very few SCR accidents despite SCRs always having a much higher WOB than CCRs - most diving on them is shallow (ignoring units designed for ultra deep diving). Even accounting for the likelyhood that SCRs are relegated to the garage earlier and users generally did less dives on them than a eCCR diver, in my personal observation, the safety record is good.

Finally, just on numbers: it is not the 1% Club anymore. It is the 4% club, assuming you do not plan diving for too many years, and 30% if you do. Now that is food for thought.

Alex

UWSojourner

Hi Alex,

I don't want to continue to beat a dead horse on this thread, but ...

I'd like to see more support for your statistical methods. You've already drawn conclusions on this thread that by your own admission were 2-4x overestimated (death rates of certain eCCRs). It would seem prudent and fair to post the methodology and backup of any statistical analysis you're using.

While you are very confident ("within 10%") of certain values, IMO you should provide the basis for such confidence (if you can't post here, just direct to a website with the analysis). Review of your conclusions could only add their validity.

Cheers,

Kevin

AD_ward9

There were not over-estimated accident rates, they were UNDER estimated. That is, the number of accidents is 2 - 3 times higher than counts 18 months ago. We put the effort in, and we get an accurate number, same for units sold.

Units sold is fundamental to marketing cases, so a great of effort was put in during 2003 to 2005 on this, with spot checks every so often since then.
We will publish the list of rebreathers in use on the DL web site. This has been debated before though. Most of our sources are component suppliers, and the individuals in those companies do not want to be named for obvious reasons. When we want to get a figure, we take a unit apart and identify every unique component then contact the sources through existing channels (manufacturers we work with that buy very large volumes of material, or sometimes their direct competitors who have the same data). There are a lot of unique components in each unit: more than may meet the eye.

We are very sure of numbers on the units that have sold in larger quantities: we have published them here before. People may just have to wait for the fullness of time to see all this data from manufacturers themselves: most provide it freely already.

Alex

Ben Field

Bit off topic but....

Its interesting to see you highlighting the difference between yourself and DiveLife more now than before. So, how exactly do you and DiveLife work? As a forum we know how to take things said by Martin Parker, Kim, Leon, Paul etc. Their position is clear but do you own, work for, work with, contract for or just mates with DiveLife? I looked on the website but couldn't find any reference to staff, perhaps I missd it?

No debate from me on the numbers... I do think it bears reiterating that some of the accidents on AP units early on have pathed the way for the training and features currently available units have, no fatality is good or excusable but I think as the Inspiration was "first" out into the recreational market some level of "learning through use" was to be expected.

Lastly- if there are half the worlds rebreathers sitting unused why isn't ebay awash? Where are they all? Perhaps these people are on "breaks" from diving... either that or they are used far less than assumed and the slow rate of consumables sales is accurate. I can't think many people would sit on a guaranteed £2000+ resale value or no reason... maybe all these resting Rebreather divers are much better off than me?

__________________
www.hugsac.org.uk

AD_ward9

I assume by "Divelife" you mean "Deep Life Design Group" which employs me. It has 40 design staff. I work for the UK part of the group (Deep Life Ltd), trading details of which are published in the UK via Companies House. 5 of the 40 work for Deep Life Ltd and revenue of even the UK Ltd company is more than the global sports rebreather market. I also work as the Lead Technologist in Deep Life Design Team OOO, which directly employs a further 25 or so of the total. Deep Life's business is primarily commercial diving and professional rebreather technology, supported by design services for large companies (typically 3000+ employees), in the fields of safety critical hardware and extremely complex hardware (electronics, mechanics, supporting software). My private interest is sports diving, particularly what used to be extreme sports diving, hence the existence of a sports version of the O.R. units. Examples of some of the products we designed are in the Powerpoint in the Design Services section of the web site, e.g. the ASIC presentation.

Given this background, I am probably the least biased, from a commercial viewpoint, of anyone in the sports diving industry. I do not receive income today from sports divers, and have proven that we are not releasing sports products that we have working already just to get income. There is a problem getting people with real expertise, who are not in someway connected with something.

On commercial diving rebreathers, these are used very heavily, and there have been no fatal accidents in the industry. Professional rebreathers cover quite a span, but very low accident rates. I will split the Mk15/15.5 and Mk16 entries later today so military and sports unit data is clearer on those units: the accidents are on Mk16s, but sports divers are using Mk15s and 15.5s with some Mk16 bits on them. The commercial and professional rebreathers pre-dated Inspos by a long way, so I do not accept the learning issue: there should be no learning with people's lives - in safety engineering one does accident reviews, HAZOPs, FMECAs in depth etc, to eliminate learning on punters rather than eliminate the odd punter. It is rather sobering to realise that a sports diver is only worth Euro 1.9k, but the full cost of a professional or commercial diver fatal accident will generally run into millions of Euro. Goes some way to explain the difference in approach.

Alex