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Thanks that makes sense. But doesn't that raise the question of how gas densities were calculated in the QinetiQ database? The correctness in "absolute" terms is not as important as making sure our gas density planning is based on a calculation that is apples-to-apples the same with the way...

That's nuts. Thanks for pointing out. It's got to be more than just rounding off the 1.293 for air to 1.2 because MultiDeco seems to get this wrong for other mixes, not just air. For example, a 16/50 mix at 250' yields a gas density of 5.9 in MultiDeco but 6.37 using the gas density...

This is addressed a bit earlier in the thread (see post 26 and thereabouts). I think the answer is that it isn't really clear. Dr. Mitchell's paper is in the context of CC, but he notes that similar effects are found in the data for OC divers. Whether that means that OC divers ought to plan...

I think I'm in the same category - it's been a week+. Just wondering if it sync'd up. Many thanks!

Everything about the equipment screams a planned a dive to 100-150, which it sounds like the site would have accommodated (i.e. stuff to see). Obviously, the exact profile from the computer, not just max depth, would give greater insight. But, let's assume it was a planned 300' dive, for which...

Can't speak to what SSI requires as a bare minimum, but I know my SSI shop has an in-person class in addition to the e-learning module. That said, I would be surprised if the requirements, in addition to the written test, don't also include demonstrating that you know how to analyze a cylinder...

I do think there is a lot of good learning going on in this thread, even if ultimately much of it proves to be on topics unrelated to the cause of this tragedy. To me, that's the point of A&I. It isn't some scuba star chamber of armchair quarterbacks, or it shouldn't be. I think the latter is...

This is nonsense. You could make this argument about almost any advance in diving safety. Risk exists on a spectrum. It isn't a light switch and the fact that something is safe 99% of the time doesn't mean you ignore the 1%. This like saying "my grandpappy smoked unfiltered Camels til he was...

This is the key point. All the questions about setup, let alone speculation about other stuff, is pretty pointless and premature until this is figured out.

Thanks @tursiops. I have to think something got garbled upstream from you. Complacency is one thing, but air DIL at 300'? Between the narcosis, DIL PO2 and gas density that's hard to fathom - a triple bust. And only having 2x 40s for bailout? Another bust. Solo? I only met her in passing...

No. Top picture is an Ambient Pressure (Inspo) BOV. Bottom picture is stock footage that some TV station grabbed of, I assume, John Hanzl on his rEVO.

I read it was an Inspiration and saw a picture of her with an AP BOV. Very sad. Was lucky enough to meet her when she spoke to a group here in town. From what little I know of her, I would guess that she would be the first one to want others to (respectfully) learn from the tragedy.

I agree that it would be hard to pull together a retrospective analysis and that's not really what I had in mind. The data they reference on pp. 72-73 of their paper from "QinetiQ" was from lab test dives and seems to have been much of the foundation for the 5.2/6.2g/L recommendation. If I'm...

I don't dispute that it is an issue on OC as well - Dr. Mitchell makes it clear that though the data is sparse, the same sort of results are seen on OC - but it would seem to be even more critical on a rebreather. Clearly the physiological considerations (meaning how the respiratory system...

The gas density issue has become much more prominent and standards for gas planning have not caught up. However, I believe the issue is of much greater importance to rebreather divers that OC divers. You'll see the original paper was in that context, as well as the study that noted the spike...

I agree with all of that which sort of speaks to your second point, which is that to take advantage of the RX100s extra capabilities it's more bulk and more work and a newer diver might not be up for it. At least for me, dives have seemed to break down into "photo" dives and "dive" dives...

I don't disagree with the bottom line of @stuartv's advice, but I will say that having had an RX100ii setup before going to an A6500 and having a GP7 now, the RX100ii will take far better stills, if you do it right. Not a little. A lot. That's the only part I don't really agree with. Strobes...

80' for 45 min on EAN30 is 47 OTUs and 16% on the CNS clock (starting from 0). Your bottom PO2 is only a little over 1. Plenty conservative. Stay on the geezer gas....

Sort of a general comment made earlier and worth repeating for late comers to this thread.... The models, rules, algorithms - whatever you want to call them - that we use for oxygen toxicity (both CNS and pulmonary) are just our "best effort" to give guidance about what is likely safe versus...

I don't believe that is a correct statement of the context of the quote. What is being discussed in the Alert Diver article is using O2 while waiting to get to a chamber, not while in it. CNS hits are not a risk at that point because you're at 1 ATM (PO2=1.0). Air breaks have some relevance...