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Cave Ccr Student Dies At Blue Grotto Today

Discussion in 'Accidents & Incidents' started by The Chairman, Apr 15, 2016.

  1. DA Aquamaster

    DA Aquamaster Directional Toast ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
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    I agree, but it's probably worth some discussion of the purpose of a lights out drill in a modern cave class - whether it is CCR or OC.

    I think most cave divers and instructors would be hard pressed to recall the last fatality, or even the last incident where a team encountered total light failure. Modern primary lights are very, very reliable, and many modern LED back up lights put out more light than the primary light I started with and given burn times of 4-5 hours at that intensity and approach 30 hours at lower intensities, automatically stepping down to achieve that as voltage in the battery drops. When you consider you have 2 primaries and 4 back ups (minimum) on a team of two the odds of having to come out of a cave with no lights are right up there with winning next Wednesday's Powerball jackpot.

    The purpose however is to teach the skills needed to deal with a silt out. A potential problem for an instructor in a lights out drill is that modern computers provide a fair amount of light, so I suspect some instructors still prefer to cover masks as they apparently can't trust students to close their eyes, and/or don't like the limited ability to monitor the student(s) with brief, dim flashes of light.

    Whether you'd want to operate with no access to your primary display or HUD is probably unit specific. For example, on our KISS Sidekick mCCRs, there's no O2 solenoid to stick open, and if the O2 MAV were to stick you'd hear it, and shut off the O2 to avoid a high PPO2 condition, and if it had already occurred, you'd do a dil flush to get a known to be good volume of gas in the loop, even if you didn't trust the sensors or couldn't see the displays.

    Low PPO2 conditions take several minutes to develop, unless you are also rapidly ascending and a roll off of the O2 (which we've had happen) is a non event as you note the PPO2 going .1 low either on the HUD or on a routine check of the computer every 3-4 minutes, hit the manual add valve to correct it and notice there's no O2 bleeding into the loop when you press the button. If there are no scooters or open circuit divers around, you'll probably note the lack of sound of gas flowing through the orifice as soon as the roll off occurs. And, just like OC side mount, you should be checking for a roll off anytime you encounter a situation where a roll off could have occurred.

    -----

    In that regard, I don't think using a covered mask for a few minutes would lead to my imminent demise, however I personally don't think covering a mask at any time makes any sense in a rebreather course. At a minimum though I'd want to be confident that the instructor would right over my shoulder monitoring the loop and maintaining an awareness of the loop and the configuration of the rebreather.

    Mask covering is also pretty pointless as it doesn't reflect any real world scenario. In truly zero viz, you can still plant the HUD right up against your mask and still see the flashes, and with a missing make, you can still see the HUD happily flashing the PPO2 information from the sensors. You'd also really have to screw up to have a total silt out with truly zero viz for more than 50 feet or so. Even if you come through a few hundred feet of small, silty side mount passage and then turn the dive and retrace your route, that zero viz will have improved to at least some viz over most of the distance, and just a few inches is enough to easily see a HUD.

    ----

    We've been diving under a limited sign off for cave diving under some limited penetration distance and bailout conditions, following our technical CCR cert and pending completion of our full CCR cave cross over on our next trip. Consequently, I can't speak to full cave CCR classes specifically, and I suspect it might be a different for a CCR diver taking cave training for the first time as opposed to a full cave diver taking technical CCR training in a cave. However, running the unit without electronics is covered in technical CCR course and you have some options. Assuming the depth is reasonably constant and you're running it with minimum loop volume, you should be able to continue to maintain your set point just by adding O2 as needed as you metabolize it with no reference to the electronics. That however assumes you can maintain a steady depth and know it's the same depth. That isn't something you can do with a mask covered, unless the line you are on is at a constant in depth. Another option is to run it as an SCR, using the SCR operation to extend the off board bailout gas. The PPO2 during the dive and the deco won't be as efficient, but it's something that can be done even with variations in depth.

    We added a HUD to our KISS Sidekicks in part for redundant loop monitoring, but also in part to ensure that we could monitor the loop in low viz conditions in silty, tight, side mount passages. It works as we've been in some very limited viz (a few inches) a few times in short sections of tight, silty passage, and you can still see the HUD happily blinking the loop status.

    In that regard, the only time we're not going to be able to monitor the loop would be in the event of an electronics failure, and that's a whole different set of drills, options and responses.
     
    The Chairman and Seya like this.
  2. The Chairman

    The Chairman Chairman of the Board Staff Member

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    They have to be certified on the actual CCR the student is using! They're an idiot if they're not on a rebreather as well. They'll be racking up all kinds of deco while their student is completely clear.
     
  3. Ayisha

    Ayisha DIR Practitioner

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    I wondered if the instructor was still at depth because she still had deco and I'm guessing that your last statement alluded to this and that she may have been on OC? It doesn't appear that she is currently an instructor for the JJ but who knows whether she is certified on the JJ?
     
  4. MRKB

    MRKB Registered

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    She is an instructor on the JJ. I posted a link to the courses she teaches earlier in the thread.

    Mike
     
    Jax likes this.
  5. Germie

    Germie Tech Instructor

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    We did this in our course too. There was told: on mccr you only can go to oc bailout. On eccr you can hear your solenoid flashing. If you hear this on regular basis you know your PO2 is within 'safe' limits. You where always allowed to switch to oc or course. The idea of this skill was that if you have a short time of no viz you don't have to worry. We have done this around 10 minutes max I think.

    The neoprene covers are used here in Europe in cave courses. I don't know what is normal in Florida? It makes you don't have to put your mask off, what can be quite cold. But without mask you still have 'some viz', and you don't have any with a blacked mask. When I dive in a cave without mask, I can still see my hud. I cannot see my hud anymore with a blacked mask.
     
  6. rjack321

    rjack321 ScubaBoard Supporter ScubaBoard Supporter

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    Do you know if the O2 was right side up or inverted as is more normal on a CCR?
     
  7. The Chairman

    The Chairman Chairman of the Board Staff Member

    # of Dives: I just don't log dives
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    Unless your O2 is off. Then you'll hear the solenoid, but no hiss. The hiss isn't as pronounced.
     
  8. kensuf

    kensuf ScubaBoard Sponsor ScubaBoard Sponsor

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    rjack321 and Seya like this.
  9. The Chairman

    The Chairman Chairman of the Board Staff Member

    # of Dives: I just don't log dives
    Location: Cave Country!
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    For those that don't want to read all of the standards, here is an excerpt:
     
    Seya likes this.
  10. MK1709

    MK1709 Registered

    12
    1
    Hi there..

    first of all my deepest condolences to all affected.

    Seeing a lot of all that vague assumptions ongoing on this treat I'm a bit
    bewildered...

    @ NetDoc.. do you think its a need or purposfull posting the instructors full name in here?

    Do anybody knows if the accident happened while entering the water and on decent or way back? If its on decent I would not say its a black out skill issue as most skills would be practice on the way out.

    If there was two students its somehow unbelivable to not have both of them on a spot as they should act as buddy team and doing drills toghther while being monitored from instructor, ready to correct and cut the exercise any time.

    Do anybody know about the spend bottom time and depth? Was it first dive the day and which stage of the training?

    Do anybody know for sure if this happened on the open water area or cavern zone?

    As the JJ is close to the AP vision, do anybody know is there is some acoustic warning if PO2 is dangerous low or high?

    If its a true hint a closed O2 bottle happens on most CCR incidents already while entering the water. Most CCR divers been trained to have the bottles opened just two to three turns so they could act immediately in case of a boom scenario.

    In this case half a turn could make the difference and there is not sufficent flow to feed the solenoid. Being under full task load a training bing your PO2 could drop fast below the toxic 16% special while entering the water and most units and pilots will start with a low set point between 0.5 & 0.7..

    Have to add a roll off with a rebreather would be also very difficult to do.. even with the valves up they sit way lower as on a OC double and you would roll off your head first. Also using 2 or 3 litter bottles there would no need to have the valves up as your will not be able to reach them.. So I assume valves down and JJ does have a stand which is wide enough to protect the valves.

    Cheers
     
    Last edited: Apr 17, 2016

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