Last Weekend's "little" accident

[TONY CHANEY]

Nice post to remind all of us not to assume anything. My AOW instructor had a way of making that point very clear. He would write a date on a slate and ask us to write down what our age would be that year. i.e. I was borned on 10-21-1963 and he would write something like 11-21-2013. I would write while being timed 50 YO. We did good, not real good on the surface. When we got to depth and stayed there for a while we performed the same test again. We were happy with our times and finished the dive. Afterwards he showed us the slates. He had changed the year! Damn we both screwed this up. His take on the situation was never assume **** down there as well as on the surface. Thanks for the reminder DD and glad all worked out well to dive another day.

 

[dumpsterDiver]

Thanks, I think this error has something common with many errors we make. Sometimes we make a big error and sometimes small ones, but they often start out with a SMALL error. an incorrect assumption, a miscommunication, saying "north" when giving directions, when we mean south, even doing math problems in school, you make one, stupid little error at the beginning of a "process" and for whatever reason, you never go back and check or verify the original mistake or error.

When you fail to question yourself about something, you tend to just move forward with a certain level of confidence and never go back and fix the first little error and that sets you off on the wrong path (which can have very bad consequences in some situations). This is not an excuse, but I see similarities in other situations.

I found the discussion in the video link below very interesting.. What does it feel like to be wrong? Think about that for a few moments, then try to answer the question... what does it feel like to be wrong? Not, what does it feel like to be confronted with your own wrongness (and to discover the error), but what does it "feel" like when you are wrong?

Then check out this video if you have time..

Kathryn Schulz: On being wrong | Video on TED.com

 

[danvolker]

In any case, and in complete seriousness, is it the depth at which the Nitrox is used that may cause a reaction, ocular or otherwise, or is it the frequency? I suspect the latter.

The first time Sandra has a run in with the hyperoxic myopia, was about 3 weeks before the article in DAN about this issue and the time Howard Hall had it.....
It is the duration with high PO2 oxygen....because the shallow water at the Blue Heron Bridge allows a diver with a 100 cu ft tank to do 5 and a half hour long macro photography dives, and this can be done day after day...at some point, the potential for this becoming a problem increases...for Sandra it was around 4 days in a row of this using around a 40 % mix.

Aside from that....this is likely to be causing a large increase in random oxidative metabolism related byproducts like Free radicals....which normally people try to eliminate by taking vitamin C, E and Astaxanthin....

 

[openmindOW]

I think criticism and discussion is a good way for people to learn.

bashing doesn't help people to learn.

respectful, thoughtful discussion does.

 

[TONY CHANEY]

The link was very good..thanks DD.

 

[phoenix31tt]

Thank God for that fish right...

Some say that between 50-100 dives is the most dangerous for a diver because thats the time when they start becoming so confident with diving that they leave out procedures and not double/triple check everything... i can only imagine how difficult it is for somebody of your experience to double/triple check stuff...

good post and good reminder... regardless of our training/experience we are all susceptible to complacency and honest mistakes

 

[Rusty Nail]

This is my first post and the first thread I have read. I only have 25 dives under my belt and just picked up the book for nitrox certification yesterday. I don't think I could have picked a better thread to start off with. Thank you DD for having the courage and the insight to understand that posting your incident could potentially save a life. I found some helpful info in this thread. Glad your OK.

 

[tracydr]

Some of the fatal accidents that I've read about have been caused by similar errors. Not verifying that your tank is the % O2 that you think it is when you do a gas switch or jump in to do a deeper gas is a huge one and I believe I've read a few accidents where this was the immediate cause of death in highly experienced technical divers, instructors, even.

 

[TSandM]

I've thought overnight about the pony full of air. Yes, it's good to have a remedy for a potentially fatal problem underwater. But it seems to me that, rather than change your procedures or equipment underwater to SALVAGE a messed up gas choice, the place to look is at the procedures you are using to ensure that you don't end up in the water with the wrong gas. whether it's making your analysis stickers bigger, or the MOD number bigger, or segregating your tanks so that you never have the ones you don't want for a given dive, it seems to me that that's the place where the effort should be spent to solve the problem. Hoping you'll get onto an air bailout before you seize is the last, worst option.

 

[dumpsterDiver]

I've thought overnight about the pony full of air. Yes, it's good to have a remedy for a potentially fatal problem underwater. But it seems to me that, rather than change your procedures or equipment underwater to SALVAGE a messed up gas choice, the place to look is at the procedures you are using to ensure that you don't end up in the water with the wrong gas. whether it's making your analysis stickers bigger, or the MOD number bigger, or segregating your tanks so that you never have the ones you don't want for a given dive, it seems to me that that's the place where the effort should be spent to solve the problem. Hoping you'll get onto an air bailout before you seize is the last, worst option.

I agree that hoping that oxygen toxicity symptoms are recognizable at depth and being able to switch over to an air pony in those circumstances is probably not much more than wishful thinking, hopefully I never have to test if it works. On the other hand, it does put a check mark in the plus column for filling a pony with air.

Your segregating tanks idea has problems. That is exactly what got me into this mess! I thought that I loaded only nitrox tanks in my truck and I was checking their mixes as I loaded them. I assumed that I had effectively segregated the tanks, deliberately leaving the air tanks home because we had decided to not do any deep dives on this trip the night before.

The solution is simple, check the label..It was legible, I just DID NOT LOOK. Maybe a better protocol would be to check the mix when you set up the BC and then check it again when you turn on the air and check the air pressure. Maybe the protocol of checking twice would be more robust?

Also, my old computers had a feature I hated! After one nitrox dive, they would revert to 50%, so it was always a PIA to remember to re-set the mix, when commonly you are using the same mix. Now I have my computer set with a default to assume that the mix is the same as the previous dive, if I don't change it. So the elimination of the step of re-setting the computer, DOES deprive me of an opportunity to be prompted to double check the mix when I am changing tanks...

It does not need to be complicated.. just check the label on the tank.