diver death results

jradomski

it depends on the version.. I'd actually have to go through the menu, but it starts with dive now, to turn on the cylinders and whether to calibrate or not.. the cal screen wount come up on newer versions if under water, the dil prompt isnt present on the original handsets, and there is the possibility of a must calibrate prompt if the sensors are too far out from one another..

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Joe Radomski
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silent running

Thanks Joe, so it's multiple steps and the posibility that it won't inject at all if the sensors are out. Of course one could just start pushing the dil add button and make their way back to the surface, but for some reason not everybody thinks to do this. I guess it's a training/complacency issue. I for one have my hand on the dil add/ADV during the whole descent but I don't remember ever having to be told this, I think I just did it after watching my instructor. I also watch the HUD closely during descent and check my 2dry to varify the PO2 increasing. I have forgot to turn on my valves a few times, but realized it as soon as I started to try and breathe off my flat CLs and went straight for the valves and had them open in less than second. For this reason alone, I consider it crucial that the valves be easily reachable. The valves on APD units look easy enough to reach.

I have not yet jumped in the water with the unit off, but if I did, it wouldn't be much of a concern as the passive 2dry never needs turning on and I could fly the unit manually. I think there's something inbetween a start up menu/prompts and a wet switch. That would be a simple power switch on/off which would start the unit injecting imediately when switched. The one on mine is rather big and mounted on my BC inflator hose and I can turn it on easily by touch, without looking. It seems to me that if a unit is going to be fully electronic, there should be some way to allow for a quick turn on since I'm sure many people have and will jump in without turning it on. A wet switch is one way, but has big disadvantages like not being easy to keep the power shut off on the surface from spray/moisture and eating up those expensive batteries that have to be carefully put in each time. Maybe there's another way to get a fully elctronic CCR to quickly turn on in this event. Anyone got any ideas?



And I agree Stefan, the simpler the mistake, the sadder the whole thing seems. I feel awful for everybody concerned when I hear of someone dying so easily... -Andy

MarkZ

Wet switches are a double edged sword. On the one hand they prevent one from jumping into the water with the unit off but on the other by doing so they can circumvent going through the start up procedures. I am not convinced the latter is better or at least safer. The simple fact remains that it is the responsiblity of a rebreather diver to go through the set up and calibration procedures before a dive without fail. I could not imagine going on a dive without multiple verifications of the handsets and valves. AP has even gone so far as to say that one should not don a unit unless it has been turned on, calibrated and ready to dive.

Essentially for this type of accident to occur means the individual did not calibrate the unit initially or turned it off afterward, did not check the handsets before putting it on, did not check the handsets when it was on, did not check the handsets before they jumped into the water, did not check the handsets after they were in the water and on the surface, and did not check the handsets prior to and while descending. Wet switches may have helped but then again how many problems will occur down the line because of diving units that are turned on in the water but not properly calibrated?

I am certainly of the opinion that every unit has it's issues and items that can be improved upon but the fact remains that a significant responsiblity lies with the diver, and always will. Engineering can only take you so far. Automobiles are a perfect example, they are now safer and require less effort on the part of the driver then any time in history but accident rates are still high. The reasons for this is obvious to anybody who drives. Whatever necessity for concentration has been engineered out has been replaced with self imposed distractions such as cell phones, GPS, and entertainment systems that now include TV's and games.

All and all this is still tragic and should serve as a reminder to take that extra couple of minutes to make sure all is well before we jump in the water

silent running

Hello Mark, I can't think of a manufacturer that wouldn't tell you that a unit must be caliabrated and ready to dive before doning. It's a must. If you're ready to jump in the water without having cal'd at least once at the begining of the dive day, you're probably beyond the realm of normal human falibility, IMHO, and asking for trouble. The fact is that people do tend to make better decisions when on the suface as opposed to being under 5 atas of pressure-it's a bit unlikely that anybody would jump in without any prep at all, unless they were sleep walking, er sleep diving...

All that being said, I still think a fully electronic CCR needs to allow for people fully preping the unit and then jumping in without turning it on as even with minimal training, this is a more likely and apparently dangerous scenerio than not preping it at all and jumping in with it on...

MarkZ

I understand you logic and reasoning and even AP deceided to go with a wet switch in the vision handsets but this is a mixed blessing. You are assuming that a person has gone through the calibration procedure. By virtue of the wet switch one can technically circumvent that requirment. It is this very reason why AP resisted putting wet switches on their units. All things considered I believe that they would have rather not done so but there was so much noise about it's lack being a design flaw that they took the path of least resistance rather then continue to argue it was a design specification. I can see both sides of the argument. Bottom line is that if people do not follow the established procedures for diving their particular unit bad things will happen regardless of how many fail safe devices are engineered into a unit.

schford

I disagree I think we need to take responsibility for our actions - I keep coming back to the rebreather that you need to take the most repsonsibility for eg the KISS is the one with no deaths.

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Stephane

Yes, you are right on this point.
But I don't follow you on the reason why this manufacturer didn't put wet-switches on his unit. There is a buzzer, it is very easy for them to put wet-switches and to make the buzzer scream when one jumps into the water with his controlers switched off.
Remember, we are talking about machines that cost several thousands of $/€/£, so the extra cost of wet-switches is pointless.
For me, this is not a bug, this is not a feature, it is a real design flaw.

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silent running

Stuart, it is certainly true. But I think it would be worth looking at the differences in dive profiles/styles btw KISS users and ECCR divers. An ECCR will give more freedom than an MCCR, but still requires oversight, a different kind of oversight that can be more involved than an MCCR. I think a more logical explanation is that ECCR divers take more risks on average, for better or worse, than their MCCR bretheren, hence the statistics.

But that doesn't mean that ECCRs neccesarily invite a more complacent mindset. Dived properly, I think they require more analysis/thinking and less doing than an MCCR: The unit is behaving a certain way, is it doing what it should? vs. I will make the unit do what I think it should-thinking and hopefully not doing vs. just doing. This is a dynamic that is not accounted for by the conventional idea of complacency usually involved in the E vs. MCCR debate...

But still the big question remains: Why are certain people attracted to MCCR and others ECCR? And is there any way to weed out the truly lazy ECCR divers from those who understand the trade off btw simple, regular task loading and the possibity of a task overload like hearing an increasing frequency of solenoid firing and noticing the onset of hypox due to current limited cells and still having the prescence of mind to shut down the unit power or O2 valve? It's not an easy estimation to make of oneself, much less someone else from an instructor's POV...

silent running

Yes Mark, but I really don't think anybody, manufacturers included, has an obligation to protect people from being totally reckless, like jumping into the water without preping the unit at all. IMHO we need to limit the scope of responsibility if anything is going to get done for the better. Otherwise you might as well go diving with your mother... -Andy

GuyW

Come on guys. You need to turn the unit on. You also need to turn the gas on, put sorb in it, put you fins on etc ...

The manufacturer can't protect you from all the stupid mistakes you make. And it they try, you end up with more complexity and more to go wrong. And someone still finds something stupid to do and hurt themselves.

The real issue here is you need to treat a rebreather with some respect, and run through a checklist (even in your head) before you jump in the water. Just like flying a plane or any other comlex bit of gear that will kill you if it is not managed correcty.

Wet switches are not a silver bullet. E.G. they turn the unit on when it gets wet and flatten your batteries. Ask hammerhead owners.

Guy