Functional Safety, Human Factors and General Safety Discussion (Moved from Mk VI)

[gianaameri]

You can engineer safety all you want eventually someone will figure out a way to get rid of that safety measure by ways of not paying attention or disengaging whatever safety device was installed.

Sure, but the truth is that the safety measures in rebreathers have not been engineered in the first place (i.e. to the extent required by the current rebreather standard).

Had they been engineered to take into account Human Factors (i.e. to a SIL level of at least one to meet the current rebreather standard), then you could scream at user stupidity.

However, it is not an excuse you have available until after you have taken and demonstrated that the rebreather is at least SIL one or above (i.e. better/less risky).

This fatality - although clearly User Error - was easily preventable by some simple and inexpensive engineering of the machine.

It is not Poseidon's fault at all as it is not possible to anticipate all Human Errors.

However, now that this one has happened, it gives the opportunity to take into account the incident in the context of rebreather design (and training of course and other procedural issues) and make it better/safer.

System, procedures, and controls are not written in stone. They are man-made, prone to Human Error, and man can improve on them by adopting CHANGE.

 

[gianaameri]

Well yes especially this particular manufacturer I could have imagined claiming something alike... But still it's different IMHO saying is my mission to... And is build tough smart and safe... Than claiming a rebreather is "safer than open circuit" and "fail safe"...
This particular controller being industry standard... Everyone can make his own opinion... I don't think this is the most used controller on the market and there have been lots of complaints about it... So I don't think so but people might get emotional on this...


Sent from my iPad using Tapatalk HD

O.K., here is another:

"Are Rebreathers Safe?
Statistics from DAN demonstrate that the preponderance of open circuit diving accidents are related to out-of-air events. One expert on recreational sport and technical diving has said closed circuit rebreathers (CCR) are safer than open circuit for the diligent diver because running out of breathing gas on a CCR is highly unlikely. While no type of rebreather can be said to be categorically safer than another, the extensively tested recent CCR designs with electronic monitoring are a major improvement. The quality of training may be the most significant factor affecting rebreather safety."

 

[Mr Walker]

...claiming a rebreather is "safer than open circuit" and "fail safe"...


Sent from my iPad using Tapatalk HD

I believe it's to be understood that the qoute is only true if the unit is properly set up and handled. As in a parachute is safe. If it's properly maintained and packed.

Remeber that there is one single part that defines a rebreather apart from OC equipment - the scrubber. If it doesn't have a scrubber it isn't a rebreather, not even if all the rest of the parts are all there. Not meaning to be harsh here as the situation is already sad as it is, but still...

Anyway, a tempsick might be the improvement the Disco needs to prevent this from happening again. Along with an amendment in the start up test that gives a "NO DIVE" unless the unit has been pre breathed until a reaction in the scrubber is detected.

/nils

 

[CFU]

O.K., here is another:

"Are Rebreathers Safe?
Statistics from DAN demonstrate that the preponderance of open circuit diving accidents are related to out-of-air events. One expert on recreational sport and technical diving has said closed circuit rebreathers (CCR) are safer than open circuit for the diligent diver because running out of breathing gas on a CCR is highly unlikely. While no type of rebreather can be said to be categorically safer than another, the extensively tested recent CCR designs with electronic monitoring are a major improvement. The quality of training may be the most significant factor affecting rebreather safety."

That is so wrong! You are claming it is safer because you eliminated one risk but therefor buying yourself in with many others!

Thats like ok I exchange my station wagon for a sports car because if I drive faster it takes more kinetic energy to get my off the road, but you are ignoring the other significantly increased risks that are coming with this.
In terms of rebreathers, you might not run out of gas, but you die because you forgot to insert the scrubber? Or hyperoxia, or bad cells, or flooded loop, scrubber channeling... risks may differ from unit to unit

Sorry does not convince me at all that (recreational) rebreathers are safer than
(recreational) open circuit.... even though some "high profile" most likely agency representative gave this answer and was put on the DAN website... or wherever...

 

[gianaameri]

That is so wrong! You are claming it is safer because you eliminated one risk but therefor buying yourself in with many others!

Thats like ok I exchange my station wagon for a sports car because if I drive faster it takes more kinetic energy to get my off the road, but you are ignoring the other significantly increased risks that are coming with this.
In terms of rebreathers, you might not run out of gas, but you die because you forgot to insert the scrubber? Or hyperoxia, or bad cells, or flooded loop, scrubber channeling... risks may differ from unit to unit

Sorry does not convince me at all that (recreational) rebreathers are safer than
(recreational) open circuit.... even though some "high profile" most likely agency representative gave this answer and was put on the DAN website... or wherever...

I agree rebreathers are very dangerous.

I was just quoting a second example of the way they are marketed.

Poseidon marketing is not dramatically different from the marketing of other mainstream rebreathers.

Sent from my HTC Desire C using Tapatalk 2

 

[opheim]

Poseidon marketing is not dramatically different from the marketing of other mainstream rebreathers.

I would disagree. But that has two sides - for one I find Poseidon to be using very "factual statements" regarding the units safety, instead of proclaiming a vision/goal/strategy for the company and/or product development. The second - equally important - is their target audience. Where many of the largest CCR manufacturers target "advanced" divers (with marketing topics about depth capability, scrubber durations, wob, redundancy, robustness, military applications etc), Poseidon is intentionally targeting the less experienced audience with their comparisons to OC. Personally I think they should be more responsible and careful about their claims, precisely because their target audience can't be expected to hold the level of knowledge and experience that would allow them to see through all the marketing BS.

 

[gianaameri]

I would disagree. But that has two sides - for one I find Poseidon to be using very "factual statements" regarding the units safety, instead of proclaiming a vision/goal/strategy for the company and/or product development. The second - equally important - is their target audience. Where many of the largest CCR manufacturers target "advanced" divers (with marketing topics about depth capability, scrubber durations, wob, redundancy, robustness, military applications etc), Poseidon is intentionally targeting the less experienced audience with their comparisons to OC. Personally I think they should be more responsible and careful about their claims, precisely because their target audience can't be expected to hold the level of knowledge and experience that would allow them to see through all the marketing BS.

Advanced divers are equally prone to Human Error as less advanced divers.

I have personally met far more sensible, intelligent, careful, dedicated, honest... less advanced, than more advanced divers.

Perception and cognition plays a big role in determining behavior.

If you provide less than complete information to either advanced or less advance divers, both being human, and both using perception and cognition to project against theoretical mental models the likely outcome of their behavior, then assuming they are equally intelligent, in both cases the wrong action (i.e. Human Error) is the likely outcome.

Mislead the dum dums, and you have an even worse outcome (more human error and fatalities).

I have great belief in the capabilities of the Human brain and in Humans.

Human Factors is what has made the human race so successful at overcrowding and dominating earth.

The overwhelming majority of Human decision lead to the correct outcome for the survival and reproduction of the species.

The ones which tend to be the most consistently incorrect ones, leading to Human Error and fatality, are those predicated on less than truthful information.

Bit philosophical and theoretical for an Operative, but there you go.

Food for GLOC and his Ph.D.

 

[Mr Walker]

Human Factors is what has made the human race so successful at overcrowding and dominating earth.

The overwhelming majority of Human decision lead to the correct outcome for the survival and reproduction of the species.

The ones which tend to be the most consistently incorrect ones, leading to Human Error and fatality, are those predicated on less than truthful information.

Bit philosophical and theoretical for an Operative, but there you go.

Food for GLOC and his Ph.D.

Human sex drive leading to poor decisions amongst RB-divers. Now that will make some interesting reading in a Ph.D. :banana1:

/nils

 

[ebt]

Human sex drive leading to poor decisions amongst RB-divers. Now that will make some interesting reading in a Ph.D. :banana1:

/nils

Ha. Reminds me of the goldfish joke....

 

[opheim]

Advanced divers are equally prone to Human Error as less advanced divers.
[...]
If you provide less than complete information to either advanced or less advance divers, both being human, and both using perception and cognition to project against theoretical mental models the likely outcome of their behavior, then assuming they are equally intelligent, in both cases the wrong action (i.e. Human Error) is the likely outcome.

Absolutely, none of us are immune, we definitely agree on that. My point is that there seems to be a lot of experienced / advanced divers who react to the marketing BS from Poseidon, whereas a less experienced or even non-diver doesn't have the necessary knowledge to recognize it.

A perfect example: According to Poseidons marketing (front page of MKVI information on poseidon.com):
"Poseidon’s MKVI has 5 big advantages over traditional open circuit equipment: 3 hours typical dive time, Safer and easier to use, Lighter and smaller, No decompressions stops"

Cool, so you can go diving for 3 hours and have no decompression stops? That is quite impressive! Because an 80 minutes @ 30m dive with my twin 12L+Alu80 bottomstage of nitrox 32 gives me a whopping ~50 minutes worth of decompression. Even utilizing O2 @ 6m, it still demands 20-25 minutes of deco. Can the first one to try that on the MKVI with no decompression stops please let me know how it works out? Or even better - 100-120 minutes? Or how about just doing 50-60 minutes at 40m? This is bullshit, and Poseidon should remove it or at the very least rephrase it.

 

[gianaameri]

Absolutely, none of us are immune, we definitely agree on that. My point is that there seems to be a lot of experienced / advanced divers who react to the marketing BS from Poseidon, whereas a less experienced or even non-diver doesn't have the necessary knowledge to recognize it.

A perfect example: According to Poseidons marketing (front page of MKVI information on poseidon.com):
"Poseidon***8217;s MKVI has 5 big advantages over traditional open circuit equipment: 3 hours typical dive time, Safer and easier to use, Lighter and smaller, No decompressions stops"

Cool, so you can go diving for 3 hours and have no decompression stops? That is quite impressive! Because an 80 minutes @ 30m dive with my twin 12L+Alu80 bottomstage of nitrox 32 gives me a whopping ~50 minutes worth of decompression. Even utilizing O2 @ 6m, it still demands 20-25 minutes of deco. Can the first one to try that on the MKVI with no decompression stops please let me know how it works out? Or even better - 100-120 minutes? Or how about just doing 50-60 minutes at 40m? This is bullshit, and Poseidon should remove it or at the very least rephrase it.

I guess there is no deco stops because the software (first release) does not allow deco dives :haddock:

Marketing hype is what is used to sucker a buyer into buying one product over another and there is so much of it because it works.

No big deal I guess, so long as key information is not withheld.

Withhold key information, then you create a false projection, leading divers in a behaviour which is more risk than what they would do otherwise.

So, Human Error is a consequence of the quality of the information (Perception and Cognition) provided to the diver, and also of course of the individual ability of the diver to put it in the right context (Projection).

However, if Perception and Cognition is off, then the odds is that behaviour will be the wrong one.

Food for GLOC!

 

[gianaameri]

If you build your unit as if it was the first dive on that unit the odds of having a problem are small and if you have the discipline to do that you likely have the discipline to handle issues if the arise.

There are a lot of people with superior skills and mental attitude who were that and believed that, but are dead, and this in all fields of human endeavours.

Good attitude and preparation cannot offset the weaknesses of crap equipment when the equipment can kill you without warning and you are incapable of self-rescue.

There are unavoidable high risks inherent in current rebreather technology and everybody dies, the good, the careful, and the unwary.



Sent from my HTC Desire C using Tapatalk 2

 

[bletso]

There are a lot of people with superior skills and mental attitude who were that and believed that, but are dead, and this in all fields of human endeavours.

Good attitude and preparation cannot offset the weaknesses of crap equipment when the equipment can kill you without warning and you are incapable of self-rescue.

There are unavoidable high risks inherent in current rebreather technology and everybody dies, the good, the careful, and the unwary.

I had to read the post twice, but got your point.

As I have mentioned before, every rebreather carries the design limitations of its designer/s. There is however one common weak point on all rebreathers and that of course are the sensors. Compounding that, there are the limitations of 'voter logic' and the approach each system takes to mitigate the problem of a bad sensor, (or two).

As pointed out in various threads, training and experience don't guarantee a favorable outcome. They can help. Too much emphasis too early on in problem resolution rather than bailing out can complicate the outcome.

Blaming the rebreather for an omitted scrubber is IMO counter productive. The real problem was with the diver, as are most incidences. There is no panacea! No one has every succeeded in designing out the "Human factor". In the real industrial world we still see accidents in the workplace because someone bypassed a safety or safety protocol.

IMO, you made three very important simple points!

Safe Diving

 

[gianaameri]

I had to read the post twice, but got your point.

As I have mentioned before, every rebreather carries the design limitations of its designer/s. There is however one common weak point on all rebreathers and that of course are the sensors. Compounding that, there are the limitations of 'voter logic' and the approach each system takes to mitigate the problem of a bad sensor, (or two).

As pointed out in various threads, training and experience don't guarantee a favorable outcome. They can help. Too much emphasis too early on in problem resolution rather than bailing out can complicate the outcome.

Blaming the rebreather for an omitted scrubber is IMO counter productive. The real problem was with the diver, as are most incidences. There is no panacea! No one has every succeeded in designing out the "Human factor". In the real industrial world we still see accidents in the workplace because someone bypassed a safety or safety protocol.

IMO, you made three very important simple points!

Safe Diving

O2 Sensors are integral part of the rebreather design and it is the designer responsibility to integrate the O2 Sensor in the design.

Same with the scrubber.

Functional Safety requires Human Factors to be taken into account, and it is not entirely unreasonable if someone is told the rebreather is "EN14143:2003" to expect a rebreather to be made fail-safe (i.e. NOT DIVEABLE) especially in the absence of, for example, O2 Sensors or scrubber.

If the user perceives a rebreather to be safer than it is, then the user will behave accordingly, and more likely than not die of Human Error.

In the specifics the user made a gazillion Human Errors, first of which going diving and Solo at 10 -12 or so meters with a rebreather thinking it was as safe or safer than OC (and did not even open the rebreather to make sure the scrubber was inserted).

The mental attitude towards the machine was not right in the first place.

 

[bletso]

O2 Sensors are integral part of the rebreather design and it is the designer responsibility to integrate the O2 Sensor in the design.

Same with the scrubber.

Functional Safety requires Human Factors to be taken into account, and it is not entirely unreasonable if someone is told the rebreather is "EN14143:2003" to expect a rebreather to be made fail-safe (i.e. NOT DIVEABLE) especially in the absence of, for example, O2 Sensors or scrubber.

If the user perceives a rebreather to be safer than it is, then the user will behave accordingly, and more likely than not die of Human Error.

In the specifics the user made a gazillion Human Errors, first of which going diving and Solo at 10 -12 or so meters with a rebreather thinking it was as safe or safer than OC (and did not even open the rebreather to make sure the scrubber was inserted).

The mental attitude towards the machine was not right in the first place.

My point on the O2 sensors was more on their reliability, something the rebreather manufacturer can only take so far. Too much regulation and you get other manufacturers of sensors to pull out of the very small diving market.

IMO, the more sopfisticated a breather becomes in some ways the more unsafe it becomes just due to human reaction to the perceived safety of the unit. There is some sweet spot where one weighs the cost/benefit ratio of a design. Too much and the unit will be priced out of the market. It will be very safe if no one dives it. Too little attention and you can also have problems and safety issues.

Perhaps the biggest problem here is that we perceive Poseidon designed too safe a unit and in that case perhaps we have bought into their sales hype! One should never put too much faith in the safety of any rebreather. One has to dive them defensively!

 

[gianaameri]

IMO, the more sopfisticated a breather becomes in some ways the more unsafe it becomes just due to human reaction to the perceived safety of the unit.

If automation does indeed increase safety, then perfectly acceptable for the Human perception to perceive the rebreather to be safe/safer.

The problem here is that rebreathers in general are perceived - due to the marketing bollocks driven by the profit motive - to be safer than they really are (with or without automation).

The technology is not there - to begin with O2 Sensors which are integral part of the rebreather - to class a rebreather as safer or as safe than OC... and they do not even meet the essential requirements of the rebreather standard being "less than SIL one" (and nobody is told when they buy or train on a rebreather).

Expectations as to performance and risk of the machine and technology are entirely out of proportion with the true risk the diver takes.

No wonder his attitude was wrong.

I would not even remotely dream of going diving Solo with a rebreather in Open Water for a 10 - 12 meter dive (let alone not check the scrubber was in).

BUT that is because I know how dangerous a rebreather can be in the first place.

 

[Ben Field]

There are a lot of people with superior skills and mental attitude who were that and believed that, but are dead, and this in all fields of human endeavours.

Good attitude and preparation cannot offset the weaknesses of crap equipment when the equipment can kill you without warning and you are incapable of self-rescue.

There are unavoidable high risks inherent in current rebreather technology and everybody dies, the good, the careful, and the unwary.

It has been proven time and time again that skill and prep can overcome incredibly rubbish equipment and danger- people have climbed most of the world high mountains in nothing more and Wool jumpers and heavy boots!

What you really mean is that- Periodically Good people encounter events beyond their skill or equipment and die, this is terrible, inevitible and unavoidable.


I believe no equipment kills without warning ... the warning for CCR is widely stated in the training/buying, anyone Stupid enough to buy and train on CCR knows the weaknesses and risks.
If anyone who buys a rebreather believes just because a company sold it to them who sound like they know that they are doing it "must be safe" they should hand themself in at the local asylum!

Therefore there are NO Unwary CCR divers.

Lastly- What is wrong with unavoidable high risks?
They are an element of many sporting and hobby activities- why should submarine exploration by self-contained breathing apparatus be "safe" for pity's sake??

I really object to the constant pointing out of this without any substantive ideas on how to go about solving the percieved problem.
(Then to go on diving an ECCR while telling us how impossibly dangerous it is makes me want to question your sanity

IMO- Except that the choice of Rebreather is risky, dive MCCR, regularly test the system while diving and understand the physcis and biology as much as you can, do all maintenance yourself and thereby accepting full personal responsibility for your unit and life.

 

[opheim]

If they're honest about what constitutes a solo dive, I'd be surprised if it wasn't a majority.

Probably varies a bit between different communities. I wouldn't even consider it. I'm lucky to have a very good long time buddy using the same unit (and with similar training as myself - most courses done together), and the rest of my friends (on OC) I regularly dive with have received pretty thorough instructions, some of them have even undertaken trydives with our units - partly for fun, and partly to know more about what we are doing.

According to DLs fatality list, more than a third of the CCR fatalities were solodives. Hard to say wether that is a lot or not since we don't know the amount of team vs solo ccr dives are actually performed, but to me it sure seems to be "more than its fair share". How many of these could have been prevented by a competent team?

A solid team makes diving safer, more fun and more rewarding.

:cuddle:

 

[bletso]

IMO- Except that the choice of Rebreather is risky, dive MCCR, regularly test the system while diving and understand the physcis and biology as much as you can, do all maintenance yourself and thereby accepting full personal responsibility for your unit and life.

For the most part that has worked for me, but even then occasionally Murphy will try to test your metal.

Gianaameri.. I have dove solo and most of my dives are less than 15 msw. Even on deep dives we all must come shallow to get out. I have dove with OC divers but I do tell them not to take my mouthpiece out and I do carry off board bailout. My regular dive buddy dives a similar but different unit. We both started with the same basic SCR and converted them MCCR.

The point here is that a CCR diver should be very self sufficient and as stated above never depend on someone else do do your maintenance. I realize that with MCCR that is probably a bit easier and is definitely less complicated. We have looked like a mobile dive shop at times and have been known to breakout a soldering iron and make on spot repairs. As we made our own units you will never hear us complain. Who could we complain to, it's just part of diving our units. BTW, I would never make and sell a like unit to anybody else.

Safe Diving

 

[gianaameri]

It has been proven time and time again that skill and prep can overcome incredibly rubbish equipment and danger- people have climbed most of the world high mountains in nothing more and Wool jumpers and heavy boots!

Time and time again people come down the mountain tied to the same rope without anchor, top guy slips, and down they go.

They do it with cotton shirt too.

You are writing non-sense, but YES people use "suicide-pact rope" and do all sort of stupid things and get away with it - often not.



Sent from my HTC Desire C using Tapatalk 2