2 Finnish divers dead, 3 injured in Plurdalen / Norway

[FinnMom]

I think the surviving divers all met at some point having completed the traverse (so they went through the deep section at 129 meters, and the major restriction at 110 meters thereafter, and then exited from a different point where they entered).

From reading the report in Finnish I understood:

All divers entered from the same place. They apparently intended to exit from the opposite end after about 5 hours.

Divers 1 and 3 exited from the opposite end after dives that were more than 8 hours. Diver 5 never went through the restriction where Diver 2 was caught (nor did Diver 4). Diver 5 exited from the point from which he had entered the cave system, which was a longer route than that taken by Divers 1 and 3. Diver 5's dive was more than 11 hours.

A very good translation of the Finnish Divers Federation report
https://docs.google.com/file/d/0B-iDm0Pmt3MYU3hxb0tZS3llTGpWVnZ0RWlPeDY5NTJybFVF/edit?pli=1

 

[gianaameri]

I see. This is a pretty surprising revelation for me considering anytime in my life dealing with life or death situations and mechanical gear, both in the military and in the civilian world, the main consideration when choosing a piece of kit for a particular mission is reliability. All other factors come in second place and below, ie extended range, portability, comfort, etc.

It seems that in the CCR world, reliability takes a back seat to the advantages of convenience of CCR while downplaying the importance of reliability. This ideology would never survive in any other life threatening activities that I've ever known, including firearms, personal defense, parachuting, rappelling, tree climbing and felling, riding bulls, and others.

Am I missing something on this or is this just the risk CCR divers accept?

CCR offers logistical advantages over OC in a few select circumstances (i.e. deep and/or long penetration cave dives).

So, it was the appropriate choice for this dive, but only a portion of it (in hindsight at least).

Certainly the deep section and the restriction could and should have been done on OC.

Even then, if a Meg ISC with 8 lbs. Radial would have sufficed for the remainder of the dive it is not 100% clear-cut.

I'd guess the probability of failure would have been greater than 5% (as much NEDU ascertained, the Meg has a 5% failure rate if memory does not fail me... imagine the other rebreathers which are not as good and may be the ones used in this dive).

The NEDU report: http://www.dtic.mil/dtic/tr/fulltext/u2/a549996.pdf ("The UBA failed in 4.9% of the 61 dives analyzed.").

 

[KellyAsh]

I see. A <1% failure rate sounds better to me, lol. I guess I'll wait until the CCR failure rate matches my MK25 regs' to get into CCR since I'm not getting paid to dive. I'm sure this is one of the main focus' of pretty much all the CCR companies though.

Thanks for the info.

 

[gianaameri]

I see. A <1% failure rate sounds better to me, lol. I guess I'll wait until the CCR failure rate matches my MK25 regs' to get into CCR since I'm not getting paid to dive. I'm sure this is one of the main focus' of pretty much all the CCR companies though.

Thanks for the info.

You'll be in for a long wait.

I did a research piece at University (a loong time ago) and off the top of my head the failure rate of the best regs. back then was a little over 2%.

This was pre Mk25 (but if anything although performance has increased, so has complexity, hence reliability is maybe worse now than back then when I did my research).

Still, OC is far far simpler and safer than rebreather and other than for extreme dives like this one OC side-mount (which reduces the failure rate of the system to maybe less than 0.04% guesstimate) is the obvious choice.

In this dive, sidemount OC with backmount rebreather and enough stages and a mix of OC and CCR may have been a safer plan (still a very extreme dive and challenge).

 

[Subcooled]

Would a SCR have been safer?

 

[gianaameri]

Would a SCR be different?

Lähetetty minun GT-S7710 laitteesta Tapatalkilla

Unsuitable for this dive, given the depth (but as this is internet I am sure someone knows better...).

 

[KellyAsh]

What, in your opinion, would it take to create this level of CCR reliability, barring all consideration for cost or current technology, gianaameri? More or different sensors or more sensors and gas controllers? Go crazy with it, lol, and give me a <1% failure rate CCR unit.

 

[gianaameri]

What, in your opinion, would it take to create this level of CCR reliability, barring all consideration for cost or current technology, gianaameri? More or different sensors or more sensors and gas controllers? Go crazy with it, lol, and give me a <1% failure rate CCR unit.

Bill Stone could not do it.

No one can.

Current technology does not allow it, but the Meg can be improved and the risk of a dangerous failure reduced by user modification somewhat (so if it is not too expensive, why not!).

Still, no user modification could further improve the ISC 8 lbs. Meg Radial and in this dive that would have been the constraining/limiting factor. Other rebreathers are behind the Meg in scrubber performance (and WOB) reason why I reference the Meg (and I am familiar with it).

 

[PfcAJ]

Unsuitable for this dive, given the depth (but as this is internet I am sure someone knows better...).

Depends on the SCR, doesn't it?

 

[TONY CHANEY]

In this dive, sidemount OC with backmount rebreather and enough stages and a mix of OC and CCR may have been a safer plan (still a very extreme dive and challenge).

I am with you pertaining to rebreathers. Where I am missing your point is where do you get the info. / idea that they did not plan to go on OC at the deep protion of the dive?