Accident in Finland

[Mr Walker]

I haven't heard of issues with wet contacts since the early aladin computer with graphite wet contacts, and uwatec solved that problem years ago. I must have done well over 1500 dives using an aladin pro and another 200 - 300 with a uwatec galileo with wet contacts. I can't recall either failing to turn on when hitting the water, salt or fresh.

I've been through Aladin Pro (bought around 1994 I think), Aladin Air (bought around 1997) and still have the Aladin Smart Com (bought sometime 2001 or 2002). I've loved them all but I've also seen some strange behavior with all of them concerning wet switches. With the Smart Com I have to rinse it in fresh water after every dive in order to have it shut down and preserve batteries.
So I guess we have different experiences...

/nils

 

[Mr Walker]

Nils,

Since this thread is already hopelessly off track, I guess I'll contribute even more by responding to your post. I must respectfully disagree with your comment that wet switches contribute to increase in lack of attention to pre-dive protocols. I believe if you were to look at actual fatalities and near misses, you will find equal prorated numbers of divers doing stupid things like jumping in the water with o2 turned off on all different units. (Again, I am not implying this what happened in this case)
Units without wet switches do not show lower fatalities , from what I can see.

Regards,
Randy

Well, discussing wet switches in fresh water is on topic in this case, it is to me anyway.

I'm not saying that this accident happened because of the diver trusted a wet switch that didn't work in fresh water. I'm not arguing that wet switches are inherently dangerous and should be banned. All I'm saying is that the possibilty that a wet switch failing can contribute to an accident such as this and it should be considered and above board until ruled out by proper investigation. Perhaps this is something we can agree on?

Personally I don't see a need for a wet switch on my controller since it's up and running long before entering water.

/nils

 

[Andy Del]

Well, this has been an interesting discussion! :read: Apart from the rather disappointing few who just have to put their $0.02 in with their guesses, rather than speaking from a point of knowledge.

Why has NO ONE said the plainly obvious? The diver who sadly passed away did not know his PO2, and missed that ever-so-slightly cardinal concept:

know your PO2 at ALL times​

Right. Done. I said it after reading 18 pages of assumptions, speculations, wrong information and point scoring.

As far as specific units go, I was trained on a classic KISS by one who was (well, almost) a RAN clearance diver. A downunder version of a SEAL if you will, but with a few tricks up their sleeves.

My point above was the number one consideration. Done, dusted and finished with. It covers all situations apart from CO2 as far as breathing gas is concerned. The technique one uses to do so was pretty simple: look at your displays. So for all the nay-sayers and complainers about HUDs and bright light, it should be quite clear: if you can't see your HUD, look at the freaking displays on your arm!

I wouldn't have thought it so hard. But, semantics and 'willy waving' appear to have diluted what should have been a clear learning point for all.

I wrote up, and deleted my thoughts and procedures on all 3 types of unit I dive. Apart from a controller and configuration, I do the same on each as far as diluent setup, surface and diving procedures go, and preparation and predive setups go. Nothing fancy and nothing idiot proof, just a careful, safe and easily remembered / written down process.

cheers

Andy

 

[Chris Brown]

Just some quick clarification on the Vision Electronics

Wet switches were recently added to meet PADI type R requirements

The vision deliberately fires the solenoid when powered up. Its so you can hear its working.

So does the sentinel and lots of other CCR's. Its a safety feature. As soon as electronics are switched on - the unit attempts to maintain set point

Personally, I see no need for the .19 SP to 'save the solenoid' or however someone put it as AFAIK theres no difference in its operation on the surface in fresh air and underwater with trimix or nitrox in the loop.

 

[Janos]

Personally, I see no need for the .19 SP to 'save the solenoid' or however someone put it as AFAIK theres no difference in its operation on the surface in fresh air and underwater with trimix or nitrox in the loop.

I've been in Scapa for a week and it's rained heavily, causing the SW to switch on. If it didn't have the 0.19 feature then I would have a flat battery in the morning.

Janos

 

[Blomman]

Personally, I see no need for the .19 SP to 'save the solenoid' or however someone put it as AFAIK theres no difference in its operation on the surface in fresh air and underwater with trimix or nitrox in the loop.

The 0.19 is of great use. Not when diving, but when testing your cells. It's also useful for saving battery in the way Janos describes.

 

[Chris Brown]

The 0.19 is of great use. Not when diving, but when testing your cells. It's also useful for saving battery in the way Janos describes.

You can test your cells in air, in a cell checker, at .7 or .4po2. Then you can change to high set point and check Mv and po2 rising. Then you can get in and do it all again on the dive. (Except the cell checker!)

What is it specifically about .19 that makes it advantageous? (I've owned 4 shearwater controllers and didnt see any benefit)

On the vision you can test the batteries by firing the solenoid. It draws a good bit and will often give you a low battery warning when you bump it up to high SP. this is allows you to swap out the battery and avoid the warning on the dive. I don't remember my shearwaters being that battery hungry. Perhaps I'm not remembering too well.

 

[Chris Brown]

There goes the neighbourhood

Lol, personally I don't like the wet connects. I keep putting the new units in the rinse tub and the electronics come on and they start beeping at you.

 

[nickb]

You can test your cells in air, in a cell checker, at .7

How does that work? I need to take readings in air, which is .21 in my money.

What is it specifically about .19 that makes it advantageous? (I've owned 4 shearwater controllers and didnt see any benefit)

Did you never download your dive log or perform a firmware upgrade?

I see no problem with the 0.19 setting and would not want to be without that option. To date, I've managed to not jump in to the water with the SW set to 0.19 or with it switched-off. I need to remember to switch to 0.7 to do a pre-breathe which, again, I've managed to remember every time I've dived my unit.

It's possible to dive my unit without a scrubber, but miraculously I've yet to do that. There are many things that, should I fail to do them, could really spoil my day. The 0.19 thing is way down on the list of those things when ranked in seriousness.

 

[nickb]

On an Inspo when the head is connected to a PC (via a cable) it detects the connection & starts up in a PC interface mode. In this mode solenoid & other stuff are non-active.

So a low set-point not required, lowest ow set-point is 0.50

Which has absolutely nothing to do with me responding to this:

What is it specifically about .19 that makes it advantageous? (I've owned 4 shearwater controllers and didnt see any benefit)

 

[Fireman]

Well I have never dove in with my controller off--impaired a little yes (hangover etc). Why add another layer of possible flaws? Dive manual. How many time do we have to have this conversation? How did dead diver XXX's ZZZZ(insert controller name) kill him or her?

And since I'm on a roll (a troll roll?) holding out the inspo's controller as an example of good design in a fatality discussion? Really?

And Yes know your PPO2 would prevent almost all mishap scenarios, but clearly that's not enough. I suppose an analysis of how quickly a unit can go hypoxic would be useful. For example with the O2 off, and/or hypoxic dil how long does one have? Throw in some task loading upon entry--swimming in a current, leaky mask etc.

So there you are on the dive boat: You put your unit on, and your one year old falls in the water, you jump in. Your PPO2 is .5, your total volume is say 6l, and (for some reason) you have 10/70 dil and your controller decides it needs a vacation too. How long before you pass out? Less than 3 minutes, maybe even less than one if you have to do some max exertion (there are some waves and current and your wife is screaming at you...)

Stay safe.

 

[Dave Sutton]

I read your post as saying you need a 0.19 setting to allow you to download dives & do firmware updates on the SW. handset powered up but solenoid OFF, just pointing out this isn't required on a Vision.

What's safer:

A system that allows a "hard solenoid off" mode

or

A system that uses 0.19 as a "soft solenoid off" mode?


0.19 is a mode that is a "soft solenoid off" mode. You need to dig thru a series of menu choices to even find it. It's not easy to select, easy to deselect, and is there "just so the diver can NEVER really have the solenoid REALLY TRULY off". But think of it as SOLENOID OFF mode.


Now:


0.19 on a Shearwater is not even available as a choice on the change setpoint menu.

You need to dig back several pages to select it on. Once it's selected as the active setpoint, it's available to immediately toggle back to high setpoint (say 1.3) on the change setpoint selection. Once you select the next setpoint (high) the only available low setpoint on the menu is the one you define (typically 0.7). Toggle between high and low is 1.3 and 0.7, with you needing to then dig WAY FAR AWAY back into the menus to re-find 0.19 again. It never appears without you looking for it. It is ONLY designed to secure the solenoid for (downloading logs, doing maintenance, calibrating without the solenoid firing, working in the rig with the can open, etc).



Much tempest in a teapot.


Dave

.

 

[MatthewA]

You need to dig back several pages to select it on. Once it's selected as the active setpoint, it's available to immediately toggle back to high setpoint (say 1.3) on the change setpoint selection. Once you select the next setpoint (high) the only available low setpoint on the menu is the one you define (typically 0.7). Toggle between high and low is 1.3 and 0.7, with you needing to then dig WAY FAR AWAY back into the menus to re-find 0.19 again.

In surface mode, 8 presses of the Menu button from the main screen gets you to the "Setpoint .19" menu item. No shovel required. It is a main menu selectable item with no sub-menus.

Once in dive mode (pressure transducer registers a change in pressure) the "Turn Off', "Calibrate", "Setpoint - .19", and "System Setup" menu items are no longer available and remain unavailable until the unit is back in surface mode. The controller will also switch the computer automatically to low setpoint if the computer was left at .19.

The Shearwater Controller uses PID circuitry to control the rate and duration of injections. That means the farther you get from your set point, the more aggressively (proportional) the system will inject O2 to keep the loop at whatever you have selected as your programmed set point.

When looking at the display in either surface or dive mode, any O2 content below .40 will have all 3 O2 sensor readings blinking red as a warning to the diver.

If a diver jumps into the water with his unit set at .19 and the blinking red O2 readouts showing ambient O2 content, one can pretty safely assume no pre-dive was done on that unit and that diver doesn't follow the first rule of closed loops "Always know your PO2". Then, it is only a matter of time before something else bites that person in the ass. I can almost guarantee it won't be a loop PO2 of less than .19 O2 because the computer failed to keep up with metabolic demands. It will be because that person never turned on the O2 tank to begin with, pays no attention to loop PO2, and doesn't follow closed-loop surface protocols as a standard practice. There is only so much "stupid" you can design out of a system while keeping the price within reasonable expectation for those users who aren't programmed to kill themselves.

RB manufacturers could certainly design out some of these undisciplined/untrained user errors with technology available today, but you wouldn't like the price of what came out of the project. It is always a balancing act between what users would be willing to pay and technology (available today) we could put into a diving unit if price were not a consideration.

I suppose even an anvil designer has to worry about undisciplined users.

 

[Dave Sutton]

^^ Excellent post, thanks.

Your

"In surface mode, 8 presses of the Menu button from the main screen gets you to the "Setpoint .19" menu item. No shovel required. It is a main menu selectable item with no sub-menus"

is exactly what I meant when I said that you need to dig back into the system to get to that setting. It's not "one left, and switch setpoint", it's "eight left and then look for it" on the screens.


Well said,


Dave

.

 

[Michael Thornton]

RB manufacturers could certainly design out some of these undisciplined/untrained user errors with technology available today, but you wouldn't like the price of what came out of the project. It is always a balancing act between what users would be willing to pay and technology (available today) we could put into a diving unit if price were not a consideration.

I suppose even an anvil designer has to worry about undisciplined users.

Great post Matthew. I feel like I started a brushfire of arguments by even bringing up design in the first page of this thread but some good discussions have come forth and I have learned some useful information.
When I originally said that

This is a sad situation, I hope that with checklists, team protocols, rebreather designs, and more knowledge we (as an industry) can eliminate more of these tragic accidents.

I meant all of those things need to work together. If the system adds too many safety features it may not be suitable or affordable. The only design feature I suggested was a vibrating HUD. (I am not an electrical engineer but I can't see this increasing the price to a point that it would no longer be affordable.) We have discussed several other options to achieve a safe rebreather, some more complicated, some less complicated. Some more expensive, some very affordable. I hope that more and more of the manufacturers, agencies etc will look at, and interact with these discussions to improve diving for everyone. I completely agree we need to improve safety without making it to expensive and or to complicated. This is what makes it difficult and why we are still progressing.
To the OP. Thanks for posting about this accident. Even though the thread has gone on tangents I feel the overall discussion will help with divers safety knowledge. New divers don't have time to learn everything in a MOD 1 class and they probably forget a lot of it. I am glad that further training exists and that there are forms like this that they can come and learn from other people's experiences rather than having to chance learning from their own near accident experience.
DAN had some interesting presentations at RF3 about what we can learn from "near accidents" rather than just accidents. These allow us to know more what is causing accidents since the divers live to tell about it. Hopefully some more of these can be posted for analysis and discussion as well.

 

[GLOC]

DAN had some interesting presentations at RF3 about what we can learn from "near accidents" rather than just accidents. These allow us to know more what is causing accidents since the divers live to tell about it. Hopefully some more of these can be posted for analysis and discussion as well.

Michael,

You might want to have a look at this presentation, which is the one I gave at Eurotek last year, about changing people's attitudes to reporting. Fundamental to getting the information out there, is changing people attitudes about 'blame', 'whose fault it was' and who is right or wrong.

The video is 60mins long so if you don't have time now, download it using your favourite YouTube clip-grabbing software and watch it later.

Regards

 

[Michael Thornton]

Michael,

You might want to have a look at this presentation, which is the one I gave at Eurotek last year, about changing people's attitudes to reporting. Fundamental to getting the information out there, is changing people attitudes about 'blame', 'whose fault it was' and who is right or wrong.

The video is 60mins long so if you don't have time now, download it using your favourite YouTube clip-grabbing software and watch it later.

Regards

I will definitely watch it. Thanks for the link What I was trying to say is that I wasn't blaming the manufacturer for the death. I gave 4 things to improve diver safety and only one was design. For example in the "near accident" that I gave as an example in my first post the only person to blame was me. I didn't do what I should have. By reporting this I can say that for sure. If I had died people would still be arguing over whether I had done my checklist, whether I was trained or whether the rebreather killed me. The best way to know the facts and the events that lead up to an accident (No matter who is to blame if anyone at all) is to analyze a near accident where this information is actually known.
On another thread I learned a ton about Immersion Pulmonary Edema (IPE) from someone who lived through an accident. The person was able to answer questions so that people weren't just speculating over what caused it. It was very educational. I don't think speculation is always bad. When some says "this could have caused it" or "it could be this", that helps people to better understand their systems and different diving environments. It is possible to do this without throwing blame.
Whether or not some of the potential problems that have been submitted as speculation caused this accident or not they can still be informative. People can learn of potential risks or problems and then learn how to prevent or deal with them. This is risk management and it increases safety. That is why I enjoy these types of threads. I don't do it to throw blame around.

 

[GLOC]

Not at all. What I was trying to say is that the majority of incidents are down to a violation of some sort, where someone has 'broken' the rules.

The problem we have in all levels of diving, but especially in the technical and CCR domains, is that the 'rules' aren't agreed by everyone, so one person doesn't think they have broken best practice but someone else does. The majority of those who commit a violation and survive know they have done so and know that they will likely change their future practices as a consequence, although there are those who don't and Darwin claims his £5. It takes a significant amount of guts (and a positive attitude) to say that you screwed up and the reason was because of 'X'.

I know of an incident where the diver screwed up after he went against the advice of the instructor as there was something wrong with the unit, he entered the water, went unconscious and floated down to the instructor/students, the students thought it was a drill but fortunately the team saved the guy's life. I asked to get some more details for DISMS but they did not want to because the 'victim/survivor' knew they had screwed up. There are a multitude of incidents like this where people are 'ashamed' of the incident they have had and the think the community will berate them. Fortunately CCRx has a pretty positive attitude to reporting and therefore people are more likely to report their mistakes...

Learn from your mistakes, better still, learn from someone else's...

Regards

 

[Randy Thornton]

I think one of the most challenging issues with regards to "rules" in the CCR community, is that different units have unit specific procedures (or rules) that don't always crossover to other units. Even those these unit specific procedures may only differ by what would mostly be considered small nuances, they can none the less affect the outcome of various emergency situations. This is precisely why I usually cringe when I hear people bemoaning the fact that they need to enroll in yet another CCR class when they switch units. As has been said numerous times previously, "we just don't know what we don't know". Sometimes "self appointed industry gurus" who give out wide ranging advice on what they consider to be "industry standards, or industry rules" can end up steering people in dangerous directions. In most cases, the manufacturer and the manufacturer's authorized instructor core, are the best current source of information for specific units. Unfortunately, a "one size fits all" book of procedures is not appropriate for the current world of CCR diving. (Now dawning my flame retardant suit!)

 

[gianaameri]

RB manufacturers could certainly design out some of these undisciplined/untrained user errors with technology available today, but you wouldn't like the price of what came out of the project. It is always a balancing act between what users would be willing to pay and technology (available today) we could put into a diving unit if price were not a consideration.

In the specifics of this accident and discussion, it would be very easy and inexpensive to roll-out some potentially life-saving remedies to the issues we discussed:

1. The JJ ADV could be moved from the t-piece in the inhale counterlung, to the t-piece in the exhale counterlung, such that any hypoxic leak is further away from the mouth and upstream of the O2 Sensors.
2. The JJ Controller could default on start-up at 0.7 with no lower than that being made available in any Menu.

I can manage, but I'd be much happier if the ISC APECS Controller in my Meg had only 3 Setpoints: 0.7, 1.0, and 1.2 (less button pushes and less chance of a user error). The Meg has the ADV as standard on the exhale counterlung (safe side!).

I see no use for wet switches. I just do not believe people jump in the water without looking at their display first. If the display is ON and it can only be in life-sustaining mode, easy enough for the user to turn-on the display/electronics and check it is ON.

As to the issues of what users would be willing to pay, easy enough.

There are Fiats and there are Ferraris.

Rather than a standard flat price for all rebreathers, rebreathers with better features and safer could be priced higher than others not as good, and give consumers a choice.

You'd have to give the performance figure of the rebreather to the user for the user to make an informed decision (i.e. WOB...) and choice.

From a moral/ethical standpoint, if a rebreather has a Probability of Failure on Demand of greater than 1 in 10,000, then you'd have to inform the user and obtain his/her informed consent before selling it, and if it is safer than that, you could fetch a higher price.

I do not see money being a constraint in respect to the small, but potentially life-saving improvements in my points 1. and 2. above.