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

[blackman]

I believe generally instructors and students do not fully appreciate the risk they are actually taking.

There is a gap between perceived risk and actual risk.

And you still dive rebreathers? But you of all should be wiser than that no?

If you are lead to believe a rebreather is safer or as safe as OC, then you will just dive it same as OC, with that frame of mind.

Awwww come on how can you be lead to believe this? In a rebreather course no instructor will ever say this!!!! .....in practically all manuals it says that diving rebreathers is dangerous and CAN kill you.....
On the other hand I never read this for bike riding and never had this level of warning when learning to drive a bike or car!!!!!

Give it a rest please!!!!

 

[gianaameri]

So now the dead are reading CCRX? (Might explain the increase in members Randy? ;-)



Then it is the instructors you should be speaking to but do you have anything to tell them they should not already know.... No, nothing you've mentioned recently isn't public knowledge.

If you choose cheap instruction from the first person you find on Google you deserve what you get. The choice of instruction is as critical as that of rebreather.



On this ONE, one death is terrible obviously but one doesn't make a statistic! We've got pages of discussion and conjecture because One person may have left the scrubber out. We've had rebreathers for 100years with the last 25-30 they've been available "recreationally" and so far (statistically) one person left the scrubber out.... lets all beat ourselves over the danger of rebreathers, thats a productive reaction :deadhorse

If only one diver had died and of forgetting to put a scrubber in, I'd be the one saying rebreather is safer than OC.

Dive Safe Ben!

I have no further time for non-sense.

Sent from my HTC Desire C using Tapatalk 2

 

[gianaameri]

And you still dive rebreathers? But you of all should be wiser than that no?



Awwww come on how can you be lead to believe this? In a rebreather course no instructor will ever say this!!!! .....in practically all manuals it says that diving rebreathers is dangerous and CAN kill you.....
On the other hand I never read this for bike riding and never had this level of warning when learning to drive a bike or car!!!!!

Give it a rest please!!!!

Bikes do not make you unconscious and incapable of self-rescue, nor cars, or toasters, or jogging shoes...

Maybe you should think of other products to compare rebreathers to.

Sent from my HTC Desire C using Tapatalk 2

 

[gianaameri]

From an earlier post I think Gian said he dived with two 18L stages.

To quote "Mr Bantin" maybe he should leave the RB behind & dive his bailout! :banana1:

18 ltr. side-mount (2).

Plus 2 Alu 80s staged, one at 600 meters, and the other at 900 meters from the cave entrance.

That is for a 3 hour dive on scooter.

Should we stay on topic?

I am getting bored to counter SPAM and non-sense.

Reminds of a now Canadian forum.

I am bailing out from responding to non-sense and OT posts.

Sent from my HTC Desire C using Tapatalk 2

 

[psmedo]

They are reading my thoughts because these great experts of yours are DEAD.

I believe generally instructors and students do not fully appreciate the risk they are actually taking.

There is a gap between perceived risk and actual risk.

This leads amongst other things to excessive risk taking and bad decisions and Human Error.

If you are lead to believe a rebreather is safer or as safe as OC, then you will just dive it same as OC, with that frame of mind.

If you realise how much more risky is than OC, then maybe on a 10 - 12 meter dive - as this one we discuss appears to be - you will not dive it at all, and leave it for dives where as a tool is more appropriate (long cave penetrations, deeper than 50 meter dives...).

But you are right, people don't always die and sometimes get away doing really senseless things.

On this one, the result was a fatality.

These are written words of an IT in RW about the DISCO - :haddock:

This little demon (MK VI) is really something! I just finished my first TDI Mk VI Discovery Air Diluent course (...) it was a huge success! It was however a big challenge for me because the unit is so easy to teach! As an instructor you keep thinking that you are underteaching in some way… because most of the survival skills you needed to teach on other units are GONE! No more flying manual, no more diluent flushes, no more changing setpoints, no more guess work about cell behavior! It is truly remarkable the way it performs! So I had to be very creative to keep them busy with skills during in water classes!

Understand fully the way it works and its benefits and then have your saying. You will be very surprised!:guitarist


RGDS

 

[Simon Mitchell]

Thanks Simon. I know Monty did this under lab conditions at DDRC for his forth coming TV programme Dive Mysteries on channel 5 - spoke to him at length in Dahab on first shoot - he was very surprised by it - thought 'I'm a big strong bloke' would have kept him exercising longer (tread mill) but as hypercapnia kicked in bad around 4 minutes he stopped 30 odd seconds later.
Simon adding exercise to it as if diving would be very interesting - the 5 min pre-breathe perhaps should be done walking about - it really would be long enough then because of increased metabolism and I would be happy in my little light MK6 and not a sentinel .

Hello Mark,

Thanks for this observation. I agree that exercise would sharpen the sensitivity, but most divers don't exercise during their pre-breathe and we will probably just run the study at rest.... at least initially. I want it to be practically useful, and to answer the question "can a 5 minute pre-breathe reliably detect the absence or complete bypass of a CO2 scrubber"? The rebreather condition will need to be blinded to the participant. In other words, some trials will involve a rebreather without the scrubber and some will be correctly assembled, but the subject will not know which is which. We will have to develop a "completely expended canister model" so that the WOB is not obviously lower when the scrubber is omitted. We will need to repeat the experiment enough times so it is not just anecdote, and so we can confidently say that a diver can detect an absent scrubber during a 5 minute pre-breathe X% of the time. We will probably move on to testing a couple of partial failure modes after that (such as leaving the O ring out of the inspo assembly). One possible outcome might be that it is easy to detect an absent scrubber with a 5 minute pre-breathe (although some have disputed this), but that partial failures are less reliably detected (or not detected at all).

Its really easy, sit on a couch as I did with a CCR2000 or any other unit without a scrubber and breathe in well under 5 minutes you will know exactly what co2 can do and have a headache you will not soon forget, then spend some time thinking about how much worse it will be in 200 feet of water.

You are being unnecessarily flippant here. You might be right, but others have done this and reported different results. We want to answer the question under properly controlled conditions with appropriate numbers of subjects so that the debate never has to occur on the internet again.

I should add that prebreathing the unit is not just about detecting CO2 breakthrough. The astute diver can also figure out whether the PO2 maintenance system is working, and other things as well. However, we will focus on detection of CO2.

Simon M

 

[psmedo]

Sorry but I am NOT writing nonsense

You simply cannot say "often not", often implys greater than 50% IMO, so you are saying dangerous activities lead to death/injury more than half the time!

Clearly thats wrong, this weekend millions of people will go Diving, hangliding, climbing, mountainbiking, solo freeclimbing, wingsuit proximity flying etc etc and only a very small percentage will get hurt.

All are activities where you are one tiny mistake from injury or death- QED Skill, Prep and Luck works "most" of the time, even if the activity is lethal.

Diving badly designed (In Your Opinion) rebreathers works "most" of the time too.

You have a very poor impression of instructors knowledge if you believe that none of them know the weaknesses of the units they teach- FWIW many of them are on here reading your thoughts!
Frankly if my instructor hadn't know his facts and figures I wouldn't been happy paying for his training- you did interview your instructor before just handing over the cash didn't you?

Good instructors MUST be, first of all, a role model of diving safety behaviour to their students. At lest they should refrain from publicly exposed themselfs as "All it just BS"

READ MY LIPS...public words written by an IT on MK VI (again)...
"We made 5 to 6 hours on each cartridge without problems. Depth is between 30 and 50 m"


MK VI Manual on the Scrubber duration; Chapter 1 page 30;
Because CO2 production rate is closely correlated with oxygen consumption, the Poseidon MKVI was designed such that the CO2 absorbent cartridge duration corresponds to the oxygen cylinder capacity. Thus, the absorbent cartridge MUST be replaced whenever the oxygen cylinder is refilled. (…) The canister has been tested for a duration of 180 minutes at 40m, water temp 4°C, and a breathing rate of 40lpm producing 1.6 l CO2 per minute at STPD (Standard Temperature & Pressure, Dry in accordance with EN14143).

- 6 hours diving at depths btn 30 and 50 meters without reffilig O2 ???

Wow what a demon.. CONSUMPTION of O2 (1 liter/minute x The Poseidon MKVI 3-liter aluminum cylinder rated to 204 bar /3000 psi service pressure).

RGDS

 

[Mr Walker]

Hello Mark,

Thanks for this observation. I agree that exercise would sharpen the sensitivity, but most divers don't exercise during their pre-breathe and we will probably just run the study at rest.... at least initially. I want it to be practically useful, and to answer the question "can a 5 minute pre-breathe reliably detect the absence or complete bypass of a CO2 scrubber"? The rebreather condition will need to be blinded to the participant. In other words, some trials will involve a rebreather without the scrubber and some will be correctly assembled, but the subject will not know which is which. We will have to develop a "completely expended canister model" so that the WOB is not obviously lower when the scrubber is omitted. We will need to repeat the experiment enough times so it is not just anecdote, and so we can confidently say that a diver can detect an absent scrubber during a 5 minute pre-breathe X% of the time. We will probably move on to testing a couple of partial failure modes after that (such as leaving the O ring out of the inspo assembly). One possible outcome might be that it is easy to detect an absent scrubber with a 5 minute pre-breathe (although some have disputed this), but that partial failures are less reliably detected (or not detected at all).



You are being unnecessarily flippant here. You might be right, but others have done this and reported different results. We want to answer the question under properly controlled conditions with appropriate numbers of subjects so that the debate never has to occur on the internet again.

I should add that prebreathing the unit is not just about detecting CO2 breakthrough. The astute diver can also figure out whether the PO2 maintenance system is working, and other things as well. However, we will focus on detection of CO2.

Simon M

Fascinating work.
When doing tests like missing o-ring or/and spacer will you also register weather a manufacturer installed co2 sensor will detect that fault before the subject does? It would in such case (and all other cases) be very interesting to know the time frame from a sensor alarm until the the subject notices by himself, has severe/clear symptoms, is impaired beyond self rescue.

On a side note, how do you convince your students to do this...? :uhh:


/nils

 

[GLOC]

Semantics I know, but Ben said

You have a very poor impression of instructors knowledge if you believe that none of them know the weaknesses of the units they teach- FWIW many of them are on here reading your thoughts!
Frankly if my instructor hadn't know his facts and figures I wouldn't been happy paying for his training- you did interview your instructor before just handing over the cash didn't you?

Just because they don't know the facts, doesn't mean they don't break the rules. The paper I referred to earlier, using incident data between 1988 and 1993-5, showed that 25% of the violations which occurred were conducted by DMs or Instructors and that 40% were conducted by 'OW-qualified' divers.

You are right that instructors should be role models, but a number (of unknown percentage of the thousands of instructors out there) either don't understand what that means or choose to ignore it (for whatever reason).

If you were bringing in a new system, you could develop your training organisation and its own QA/QC process as you saw fit and make sure that standards were actively maintained (GUE, RAID?) but if you are now trying to play catch up, unless you play hard-ball and vet the instructors and potentially kick them out, then there is no of forcing change on your instructor cadre. This is the point that I tried to raise to Mark Caney at RF3.0 during the session on training - how are you going to make sure that your instructor cadre are teaching what they are supposed to be teaching? I asked the same question in the ANDI/TDI/IANTD certification session. To me that is the first step in ensuring that the knowledge is passed down correctly and consistently...(and as Chasey pointed out in the 'Ways to Improve CCR Safety' thread)

Regards

 

[gianaameri]

Just because they don't know the facts, doesn't mean they don't break the rules.

Yes, but some people, in their mental model, would attribute the fatality to "rule breaking" and ignore entirely the fact that the rebreather is crap (i.e. it lacks Functional Safety).

I had a friend in University.

He was rich and could afford to buy a car.

I walked or took the bus.

He bought a "Yugo."

He was also a rule breaker, but that did not change the fact that the car was crap.

On day 3 the windshield-wiper flew off the windshield.

So, when he had an accident in the car, was it because he was a "rule-breaker," or because the car was crap?

I put it down to the Yugo he bought really being a really crap car.

 

[GLOC]

 

[gianaameri]

Same thing when you talk about Human Factors.

You throw Human Factor everywhere :deadhorse

It is a mouth filling word, but so is Functional Safety.

 

[gianaameri]

Back again......... :big:

Sorry, I did not mean to interrupt.

You guys talk freely about Human Factors and how it is all down to User Error and Human Factor like nothing else matters.

I take a break from the forum!

 

[GLOC]

Gian,

You might want to read up a little about Human Factors before dismissing it in the way you are...

SKYbrary - HFACS

HFACS Level 2: Preconditions for Unsafe Acts - this is broken into 3 subsections; Environment, Condition of Operators and Personnel

Environmental is then broken into Technical and Physical.

Technological Environment: Refers to factors that include a variety of design and automation issues including the design of equipment and controls, display/interface characteristics, checklist layouts, task factors and automation.

So all the system safety designs you are talking about ARE covered by Human Factors!

Regards

 

[gianaameri]

Gian,

You might want to read up a little about Human Factors before dismissing it in the way you are...

SKYbrary - HFACS

HFACS Level 2: Preconditions for Unsafe Acts - this is broken into 3 subsections; Environment, Condition of Operators and Personnel

Environmental is then broken into Technical and Physical.



So all the system safety designs you are talking about ARE covered by Human Factors!

Regards

I do not dismiss Human Factors.

I just do not think they are 100% of the picture.

Only 50%.

The other 50% is Functional Safety as it relates to the machinery.

Then there is an overlap (or a circular element) insofar for a machine to be Functionally Safe, the designer has to have taken into account Human Factors (i.e. including taking into account of accidents like this one).

So, you cannot talk about Human Factor without talking about Functional Safety, or Functional Safety without talking about Human Factor, in rebreather application.

If no machinery were involved, then you could talk about Human Factor in isolation.

BUT, in our application, machinery is involved, and its life-support is entirely dependent on electronics and human interaction.

I am taking a break seriously cause tomorrow will be the whole day shooting my Made in the U.S.A. superior technology and it is a long ride.

 

[Mike Ferguson]

XXXX is at Stoney Cove on XXX offering a unique opportunity for you to join the rebreather revolution.

Book your try dive today with XXXXXX for a unique experience on the Poseidon MkVI Discovery, the world's first automatic fully closed circuit recreational rebreather.

Poseidon’s MKVI has significant advantages over traditional open circuit equipment:
3 hours typical dive time
Safer and easier to use
Lighter and smaller
No decompression stops
Silent operation makes you part of the environment; not just a visitor.

The MKVI, the first true technological breakthrough in decades, its a real game*changer.

(clubs or group sessions and events / Mk VI rebreather presentations - ring XXXXX to discuss)

Requirements:- Certified as a PADI Open Water Diver or a qualifying certification from another
training organization, 18 years old with at least 15 logged dive

Book your PADI Rebreather Diver Course with XXXXX and qualify for the Poseidon / Sport Diver £1,300 discount on the cost of a Mk6 Discovery rebreather..

just lifted this off an ebay advert, my bold highlights, at first I thought they can't be serious and checked the date to see if it was April not May starting today. does this type of marketing make anyone else feel uneasy about what the future holds?

 

[Simon Mitchell]

Fascinating work.
When doing tests like missing o-ring or/and spacer will you also register weather a manufacturer installed co2 sensor will detect that fault before the subject does? It would in such case (and all other cases) be very interesting to know the time frame from a sensor alarm until the the subject notices by himself, has severe/clear symptoms, is impaired beyond self rescue.

Hi Nils,

I am planning to run this study in more than one rebreather, if only because the internal volume of the loop (which is no doubt different between units) potentially affects the result. I have access to one unit with an exhale limb CO2 detector (the Sentinel) and that will certainly be one of the subject rebreathers. We will obviously not let the diver see the HUD, and we will have to disable the tactile / audible alarms, but we will definitely record what the sensor is showing during the test in relation to the subject's subjective perception / symptoms, resp rate, inhaled CO2 (measured accurately) and end tidal CO2. I have a research assistant starting to work on the ethics application today. This will all take a while though

On a side note, how do you convince your students to do this...? :uhh:

Yes, a good question that I will leave to the behavioural change experts like Gareth.

Simon M

 

[Chris Brown]

XXXX is at Stoney Cove on XXX offering a unique opportunity for you to join the rebreather revolution.

Book your try dive today with XXXXXX for a unique experience on the Poseidon MkVI Discovery, the world's first automatic fully closed circuit recreational rebreather.

Poseidon’s MKVI has significant advantages over traditional open circuit equipment:
3 hours typical dive time
Safer and easier to use
Lighter and smaller
No decompression stops
Silent operation makes you part of the environment; not just a visitor.

The MKVI, the first true technological breakthrough in decades, its a real game*changer.

(clubs or group sessions and events / Mk VI rebreather presentations - ring XXXXX to discuss)

Requirements:- Certified as a PADI Open Water Diver or a qualifying certification from another
training organization, 18 years old with at least 15 logged dive

Book your PADI Rebreather Diver Course with XXXXX and qualify for the Poseidon / Sport Diver £1,300 discount on the cost of a Mk6 Discovery rebreather..

just lifted this off an ebay advert, my bold highlights, at first I thought they can't be serious and checked the date to see if it was April not May starting today. does this type of marketing make anyone else feel uneasy about what the future holds?

Whats wrong with it?

Ive taught people to dive CCR with not much OC experience and they are often more respectful of the undertaking and more vigilant than some 'know it all' OC divers who want to skip the academics (boring - I read the book) skip the pool session (Pfft Ive got hundreds of dives and you want me to go in a pool?) and who often flunk the skills because they didnt listen to the briefing

 

[ebt]

You might be reading with a bias chris. Its the 'Safer and easier to use than OC' bit that people are grizzling about

 

[psmedo]

Gian,

You might want to read up a little about Human Factors before dismissing it in the way you are...

SKYbrary - HFACS

HFACS Level 2: Preconditions for Unsafe Acts - this is broken into 3 subsections; Environment, Condition of Operators and Personnel

Environmental is then broken into Technical and Physical.


So all the system safety designs you are talking about ARE covered by Human Factors!

Regards

ABSOLUTELY the SHEEL model explains clearly the problem on it´s diferent interactions.

Safety in any industry or activitie is always function of 4 pillars; Man, machine, procedures and environment. As James Reason has put it you can change procedures, machine and environment but you can not change the man... I´m not pretending that the DIVER is at the root cause, the MAN aplies to all human interference in the SYSTEM, thus instructor, design, instruction, diver (with all the social factors included)...etc etc..

Unfortunately investigations of diving "accidents" i´d rather call them mishaps follow the Rhumb line, insted of a strait and clear line, but again the cost of human life is cheep if one here and one there once in a while, on the probabilistic risk assessments that have certaninly been done, thus not justifying action on the part of the industry. We have seen these happening in the aviation industry so frequently so who really cares about some dudes diving CCR ??

Someone put it quite cleverly that an accident in a "working scenario" is trated according the national HSE procedures including investigation.
Remeber however that HSE standards for DIVING (as work), including diving equipment specifications, and diving procedures, does not apply on the recreational diving industry at least in Portugal.

If i´m not mistaken investigation of accidents occuring in the sea falls under the maritime authority umbrela and investigations to those are requested by the public prosecutor AFAIK.

I´m not familiar with any investigation of this nature (fatality in diving) been ever disclosed to general public or even to amateur diving organizations since 1990 in this country.

Unfortunately SMS and proactive safety are concepts still too much ahead for public sercvice entities in general. Resilience engeneering, the intrinsic ability of a system to adjust its functioning prior to, during, or following changes and disturbances, so that it can sustain required operations under both expected and unexpected conditions is still a unknow science for a vast majority of important diving industry actors.

To be or nor to be "Selective breeding" or "Selective breathing" that´s the question...

we should include in the syllabus of the diving courses a little bit of William Shakespeare's play Hamlet more specificaly his famous opening phrase in the soliloquy, when Hamlet questions the meaning of life, and whether or not it is worthwhile to stay alive when life contains so many hardships. He comes to the conclusion that the main reason people stay alive is due to a fear of death and uncertainty at what lies beyond life.