Packetsniffer / Jackson Blue

[Randy43068]

What is it about RBs that cause people to just fall asleep? I'm not saying that's what happened here but man there seem to be a lot of issues with that kind of thing. The thing that really scares me, we don't have any way to really know what happened.

I posted on another board a year or two ago that it woudn't take much in the way of electronics to data-log the dive similar to a aircraft "black box" to aid in the investigation when an incident like this happens.

 

[Randy43068]

Based on what I know about Richard's gear, I really only have 3 questions I'd like answered, and 2 questions for Dan.

I just hope I get to ask them.

Why bring it up if you're not going to ask those questions here?

 

[wedivebc]

What is it about RBs that cause people to just fall asleep? I'm not saying that's what happened here but man there seem to be a lot of issues with that kind of thing. The thing that really scares me, we don't have any way to really know what happened.

I posted on another board a year or two ago that it woudn't take much in the way of electronics to data-log the dive similar to a aircraft "black box" to aid in the investigation when an incident like this happens.

That is a good point about the black box. You may be seeing them very soon. The biggest problem with RBs is the fact that our brains aren't sensitive to low oxygen the way they are to high CO2. Breath into a paper bag for a couple of minutes and then analyze the O2. You will find the it gets very uncomfortable to breath yet the O2 level is probably still sufficient to sustain life. When you remove the CO2 and let the oxygen fall the body is unaware of it and just starts to shut down. I have no idea if this is what happened here and I am anxiously awaiting some facts.
As far as I know hypoxia was the culprit in only one fatality this year and occured when the diver forgot to open his O2 valve prior to the second dive of the day.

 

[Randy43068]

While I don't dive a RB, frankly I'm afraid of them, I wonder if using a full face mask would help somehow. Maybe my assumptions are incorrect, but it appears some folks just fall asleep while using 'em, and I agree with you about CO2 as a strong possibility, so would it not make sense to use a full face mask to prevent drowning?

At the very least one on a RB would have a buddy who would notice the diver in trouble as either acting in an odd way, or not moving at all which would then trigger the buddy to take some kind of intervening action.

Still I shake my head and cannot imagine Sniffer to be gone.... I never met him, but we had many friends in common and we traded some PMs about various things. What a decent guy.. he was.

That is a good point about the black box. You may be seeing them very soon. The biggest problem with RBs is the fact that our brains aren't sensitive to low oxygen the way they are to high CO2. Breath into a paper bag for a couple of minutes and then analyze the O2. You will find the it gets very uncomfortable to breath yet the O2 level is probably still sufficient to sustain life. When you remove the CO2 and let the oxygen fall the body is unaware of it and just starts to shut down. I have no idea if this is what happened here and I am anxiously awaiting some facts.
As far as I know hypoxia was the culprit in only one fatality this year and occured when the diver forgot to open his O2 valve prior to the second dive of the day.

 

[Missdirected]

Why bring it up if you're not going to ask those questions here?

Dan, Richard's buddy at the time, has stated he is going to give a full report on what he knows (he stated this on another forum). He asked that people give him a couple of days to collect himself. Fair enough, IMHO. I think, and I may be wrong, that Perrone is just waiting for Dan to put out that report so that he can ask his questions.

Please remember this thread is for the discussion of incidents we have a condolences thread here (we don't want to have the family have to wade through this stuff for condolences ): http://www.scubaboard.com/forums/passings/253606-packetsniffer-richard-mork-passes.html

 

[jimdiverman]

I hope I haven't offended anyone by posting these thoughts. I see RBs in my diving future and am trying to learn as much about them as possible, especially concerning all the deaths involving them recently.

Rob,

I'm with you. I believe rebreathers are in my future also, but until there is an economical and reliable way to measure CO2 in the loop, I won't be diving one. I bought books and started to read about them earlier this year to understand the workings and the different types, and I spent some time with Jeff Bozanic at the NSS-CDS Workshop in Marianna in May discussing them. Everyone that I have talked to, even those that dive rebreathers, acknowledge that not having a CO2 measurement is a shortcoming.

Now I am not stating anything about this incident because I wasn't there and I don't know exactly what happened, and I am not speculating, but I am saying that I would feel alot more comfortable about diving a rebreather if I was able to monitor CO2 and take action (purge the loop) while I was still able because I was alerted by a loop CO2 level alarm, or better still, a high CO2 level measurement automatically initiates a purge in case I am unable. In my opinion, this would be a major improvement in RB technology and make me feel a lot better about taking that route and diving one.

 

[Aaron203]

... The biggest problem with RBs is the fact that our brains aren't sensitive to low oxygen the way they are to high CO2.....

I'm not a doctor (just a lowly engineer), nor am very knowledgeable about RBs, but I think wedivebc is correct. I have had to take an Air Force "Altitude Class" (not the official name) because I was involved in some flight testing of different avionics for the USAF. Anytime a crew member (whether in the AF or a contractor like me) has to go above 10k ft in altitude (I think that's the cutoff), they must take this class.

The class is about a day and a half of lecture regarding the effects of altitude (and as a result hypoxia) on the body. They teach the students that everybody's symptoms of hypoxia are different. So, they put everybody in an altitude chamber, and take them to 30,000 feet and have them remove their oxygen masks (with an instructor in their face, still on O2). This serves two purposes, 1) you determine your symptoms to hypoxia (my fingers / lips start to tingle), and 2) you get a real sense for how dangerous it is. With my symptoms, I could easily see how without this class how I could just "pass out" without recognizing hypoxia.

My question regarding RB's is can this situation occur? I realize that at altitude, the entire atmosphere is less, so you're getting less O2 and CO2, etc so it's not quite an apple to apple comparison.

At this point, RB aren't in my near future (more due to cost and interest than anything else), but I'm always trying to learn new things.

 

[lamont]

Speaking generally about RB accidents, if there was some issue with the sorb (packing, reuse, channeling, etc) its typically impossible to analyze it post-fatality due to the loop being flooded in the accident?

 

[Meng_Tze]

Aaron, yes on RB's you can get hypoxia like with altitude. This can happen in several instances: going up and not adding O2, a solenoid stuck closed, a man add valve malfunction, O2 tank closed, leaky valve clogged, not watching PO2 levels continuously, etc, etc.


Lamont,
Depending of the actual RB, some are more resistant to flooding than others. The Cis Lunar MK IV for instance has a hydrophobic membrane around the stack and apparently can take a complete flooding. There are other systems that have larger water traps and can take quite a bit of water. I do not know enough about other systems than a Meg to be able to talk about their susceptibility to flooding.

Once flooded and water has been in contact with the stack, it gets messy. Probably to the extend that accurate analysis of the accident has been impaired I would say.

CO2 monitoring would be a great addition to any RB system. But lacking that, keeping a close eye on your breathing pattern and timely bailout to OC/loop flush when things don't seem well is the next best thing.

But these generic questions may be better off discussed in a separate thread maybe under the Rebreather Forum where other rebreather users and instructors are also participating.

 

[packman]

I hope the investigation and analysis provides us with some useful information. However, I'm not too optimistic. Regardless, we all lost a good friend this day.