Is it OK to turn off O2 in Rebreather Training?

[cerich]

I seem to remember a death at Blue Grotto due to hypoxia that worked a lot like this...

It was boom drills and the instructor didn't verify the oxygen was back on before they proceeded to the next drill which was black out with no HUD or the instructor watching the PPO2 was my understanding. If that is true the instructor was a moron either for thinking it was right or not saying "this is stupid" when being taught to teach that way

 

[doctormike]

Another dive professional in PM reached out and commented on this thread that it is a great example of Dunning-Kruger in action..

Eh, that's pretty harsh. I mean, I hardly consider myself to be superior to people in general, certainly not to someone of your stature. On the other hand, it's possible to have a different point of view without it being evidence of incompetence. Which is what you are implying about me and my instructor.

It seems from other responses to this thread that other instructor trainers also do the unannounced O2 shutoff, suggesting that there is at least some controversy about the point. And let's not make this into a slippery slope - I'm not suggesting that it's OK to sneak up and cut the student's loop open. I was talking about one very specific thing.

Look, anyone can screw up anything. If an instructor shuts off a students O2 and then swims off to see if he will find his way home, that's obviously malpractice. But shutting it off and sitting there watching the student and his controller is a different thing, especially when the instructor can turn it back on long before hypoxia if the student doesn't "get it".

For any OC divers reading this thread who might not know, this is NOT the same thing as sneaking up and shutting off someone's tank valve.

 

[cerich]

Eh, that's pretty harsh. I mean, I hardly consider myself to be superior to people in general, certainly not to someone of your stature. On the other hand, it's possible to have a different point of view without it being evidence of incompetence. Which is what you are implying about me and my instructor.

It seems from other responses to this thread that other instructor trainers also do the unannounced O2 shutoff, suggesting that there is at least some controversy about the point. And let's not make this into a slippery slope - I'm not suggesting that it's OK to sneak up and cut the student's loop open. I was talking about one very specific thing.

Look, anyone can screw up anything. If an instructor shuts off a students O2 and then swims off to see if he will find his way home, that's obviously malpractice. But shutting it off and sitting there watching the student and his controller is a different thing, especially when the instructor can turn it back on long before hypoxia if the student doesn't "get it".

For any OC divers reading this thread who might not know, this is NOT the same thing as sneaking up and shutting off someone's tank valve.

I'm not saying it to be harsh at all.

To your last regarding to OC, why not? Other than number of breaths and how they present the end result can certainly be the same. OC you are more likely to get panic, CC just gone

 

[boulderjohn]

It seems from other responses to this thread that other instructor trainers also do the unannounced O2 shutoff, suggesting that there is at least some controversy about the point.

As I said earlier, this kind of training has been a part of scuba since its earliest days, although usually without the blessing of the agency. It is also arguably a better way to teach, leading to a more aware diver. Maybe.

But there is for me and for the leadership of most agencies an unacceptable level of risk in this practice. The odds are that nothing will happen, but something could happen, in which case the instructor is responsible for the death of a student. I will therefore look for some less lethal way of building a desired skill.

An example of what can happen can be seen with an OW skill--CESA. A couple of decades ago, a UHMS study of scuba fatalities during instruction identified the CESA as the most dangerous of skills during instruction, and they identified specific practices that were problematic. As a result, almost all agencies adopted very specific rules about conducting the CESA and demanded that instructors follow those new procedures carefully. The most important of these was keeping the students' regulators in their mouths. Instructors used to require that it be discarded, proving to the instructor that they were not inhaling. This had led to many drownings, because when the students did inhale, it was often fatal.

In Belgium, however, scuba agencies apparently renounced those UHMS findings and went on as usual. It is apparently still common to teach CESA with the regulator out of the mouth there, or at least it was a few years ago when we had a thread on this topic. In that thread, a link was provided to a study showing that drownings of students while doing the CESA was still the most common form of fatality during instruction in Belgium, while it is almost unknown in the rest of the world. Apparently they believe there that they are getting an instructional advantage through this procedure that is worth the loss of an occasional student's life. (I have no idea what that advantage would be.)

 

[sea_ledford]

Obviously you can teach with or without this method, I didn't say it was the only way to teach it. But it's certainly better in my mind than just telling a student that their O2 valve is closed and that they should reach around and open it.

The teaching comes from the student working through the process in real time, with real inputs and real procedures. It's obviously not appropriate for everything - I'm not saying that it's OK to cause channeling to simulate hypercapnea. But it works for this, where the PO2 drop is slow enough for the instructor to monitor it and give the student time to fix it long before the loop becomes dangerously hypoxic.

Well, the obvious argument to that is not to tell the student that their valve is closed, but rather that their PO2 is dropping. Or even tell them what the lights in the HUD are doing. Student still has to work through the problem, but isn't in actual increased danger. TDI even makes a little prompt slate for just such a teaching moment so you don't even have to write it down. If the student is in enough of a task loaded state, it will result in plenty of thought processes being tested.

-Chris

 

[doctormike]

I'm not saying it to be harsh at all.

To your last regarding to OC, why not? Other than number of breaths and how they present the end result can certainly be the same. OC you are more likely to get panic, CC just gone

Other than the number of breaths? That's the whole point that I'm making.

Six minutes is a long enough time for an instructor to watch carefully and intervene if necessary. 10 seconds may not be.

 

[cerich]

Other than the number of breaths? That's the whole point that I'm making.

Six minutes is a long enough time for an instructor to watch carefully and intervene if necessary. 10 seconds may not be.

yeah no. it's simply too high and unacceptable risk IMHO

 

[doctormike]

As I said earlier, this kind of training has been a part of scuba since its earliest days, although usually without the blessing of the agency. It is also arguably a better way to teach, leading to a more aware diver. Maybe.

But there is for me and for the leadership of most agencies an unacceptable level of risk in this practice. The odds are that nothing will happen, but something could happen, in which case the instructor is responsible for the death of a student. I will therefore look for some less lethal way of building a desired skill.

I'm not an instructor. You guys all know far more than me about rebreathers and teaching. But I will point out that at some point, every instructor puts his or her students in some non-zero danger because the teaching benefits outweigh the risks. All we are discussing is where to draw the line, not whether the line exists.

When teaching, you guys do blackout mask drills, right? Lost line drills? Bailout with real deco? Loop recovery? Lost mask swims? Training in limited visibility conditions? I'll bet that you can find training accidents linked to all of these if you look hard enough.

So this particular method is different, because you aren't telling the student ahead of time that you are going to do it. But you also have a lot longer time to watch them figure it out.

If you are telling me that the agencies forbid shutting off O2 on a CCR in this circumstance, or that you consider the risk to outweigh the benefits, I'll take that as a teaching point, because I respect your knowledge. But that doesn't mean that other respected individuals may not see it differently.

 

[cerich]

I'm not an instructor. You guys all know far more than me about rebreathers and teaching. But I will point out that at some point, every instructor puts his or her students in some non-zero danger because the teaching benefits outweigh the risks. All we are discussing is where to draw the line, not whether the line exists.

When teaching, you guys do blackout mask drills, right? Lost line drills? Bailout with real deco? Loop recovery? Lost mask swims? Training in limited visibility conditions? I'll bet that you can find training accidents linked to all of these if you look hard enough.

So this particular method is different, because you aren't telling the student ahead of time that you are going to do it. But you also have a lot longer time to watch them figure it out.

If you are telling me that the agencies forbid shutting off O2 on a CCR in this circumstance, or that you consider the risk to outweigh the benefits, I'll take that as a teaching point, because I respect your knowledge. But that doesn't mean that other respected individuals may not see it differently.

without any instr names what agencies are the instructors you know that are shutting off gas certifying with?

 

[doctormike]

without any instr names what agencies are the instructors you know that are shutting off gas certifying with?

Are you kidding? After this thread? Try Superlyte, maybe he will give up his sources...