Dutch Cave fatality - Marcilhac-sur-Célé, France

[Marie13]

I'd want one per tank.

Doesn’t work that way.

It’s becoming more common to have a transmitter on right tank with SPG on left tank (standard place for SPG on manifolded doubles).

 

[Miyaru]

According to the Dutch news article from post #5, they were on their way back, and the victim's buddy was in front after (almost) making a navigation mistake. When he looked back to check, the victim had no reg in his mouth.

Distance where the accident happened: 750m
Depth at this distance: 48m to 52m
The next T is a hundred meters farther into the cave, where the victim allegedly was about to take the wrong direction.

I'm impressed with the distance on OC, unless DPVs were used. My thoughts:

• Most likely the twinset was used in section 2. All this time the SPG didn't show a drop in pressure.
• If the manifold was closed at the start of the dive, the backup reg still would have worked.
• If the manifold was closed due to a problem while in the deep section, the diver must have been aware of a potential upcoming gas shortage and could have used the bailout gas from his CCR buddy.

Questions which I can't answer since I've only been to 630m in this cave. That is where I reached 1/3 of my backgas.

Cave profile:

 

[TheCoolBeans]

The questions I have in my own mind are based on owning and using a similar setup.

(I use Manifolded backmount doubles.
I have a normal SPG on the left post and a TX on the right post).

750metres in a cave for me is between 45-75mins of diving depending on pace.
In that time, if I’m diving with a closed manifold, I would either see an abnormal increase of gas usage via my transmitter/computer, OR, I would notice my normal SPG isn’t moving.

Either way, I’d recognise a problem.
i don’t know how you would dive for a minimum of 30mins (that’s 20m per/min pace… pretty quick without a DPV) without even a cursory glance at what gas was used.

So sad this happened, hopefully there will be lessons to learn from this tragedy.

 

[azstinger11]

Doesn’t work that way.

It’s becoming more common to have a transmitter on right tank with SPG on left tank (standard place for SPG on manifolded doubles).

When I dive doubles that is how I run it. Under normal operation I can cross check the AI/SPG to ensure both are operational/accurate, but if I had to isolate whatever tank i'm breathing has some way of reading pressure. I make it a habit of checking both everyonce in a while to prevent diving with a closed manifold (never happened to me, but it obviously does). However if I do have to isolate the dive is done, and i'm getting back to the surface ASAP.

 

[Leon_2020]

I'd want one per tank.

Why? At the beginning of kitting up, you check your manifold and valves are open. Once you enter the cave, you check again that everything is open. If you hit something, you do a valve check to check that everything is open and that you do not have a roll-off.

 

[Trace Malinowski]

Less is more.

Rich Courtney once asked me a question while filling my tanks at Cave Excursions East in High Springs. "Why do we even bother to shut down a leaking post?" What he meant by that was if we've planned correctly, the moment there is any problem with gas we should just be able to signal OOG and head toward the door.

We tend to overthink problem-solving in technical and cave diving. Another cave instructor and I became lost on a line in Manatee when my scooter quit. We were both trying to figure out the issue and referencing the guideline when we found ourselves getting the scooter going. We decided to continue the dive but we came to the end of the guideline. We somehow managed to get in a side tunnel. I started to lead out, but we never speed-matched the DPVs. I left him in the dust. I also spotted the outbound mainline and made a visual jump to it. Now, we not only had team breakdown, but we were on different lines out of sight of one another (and what if I was wrong about the line being the main exit out?). I waited for my buddy and saw him deploy his spool to do a lost line or lost buddy search. I signaled to him, but he didn't see my light. I fetched him and we exited. Eventually, we figured out we were sucked into the Milk Tunnel (siphon), that we forgot to match speed, and that it's too tempting to use a DPV to make visual jumps.

What was our goal when my SUEX XK1 quit? To go home. Why did we mess around with it and waste time? We should have just rigged for a single DPV towing a broken DPV exit and left. We would have had all day to fix it on the surface. Same with gas. As Rich Courtney pointed out, we should just get to the door and not waste time trying to solve manifold issues when we are most likely going to thumb a dive even after we get it sorted.

I'm not saying this is the solution. It is a possible solution. It's definitely a campfire or fill shed chat, but Rich had a good point to consider about just going home since we have the gas. And, the less time we waste, the more gas we have to get us home.

 

[Leon_2020]

For me, the most important item on the list is why did it make sense to the diver to do whatever he/she did at that point in time? What led him/her to make that decision?

If we understand the answers to the questions above, can we start to work on a solution.

 

[Nick_Radov]

I'd want one per tank.

You don't want one SPG per tank for doubles with an isolation manifold. A single SPG on the left post is sufficient. Adding another on the right post doesn't tell you anything useful, adds a failure point, and complicates hose routing. As long as the left and isolator valves are open, the single SPG tells you the pressure in both tanks. If there is any sort of failure which forces you to close a valve then the dive is over anyway so you will make an immediate safe ascent to the surface (including any mandatory deco). Since we do gas planning before entering the water we know we have enough extra gas in the team to get out even if one diver had a complete loss of back gas. No need to worry about pressure in the right tank.

From the accident description it seems like maybe the isolator valve was closed at some point, perhaps before the dive even started? There have been incidents where poorly trained gas mixing technicians did stupid things like closing the isolator valve, and filling oxygen in one side and helium in the other. Or only topping off air on one side. Or other variations of similar errors. So you can end up with completely different mixes in the left and right tanks possibly with dangerous oxygen levels. That's why we always verify the isolation valve is open before doing gas analysis. And then one of the pre-dive checks is to do a flow check and verify that all three manifold valves are open.

 

[PfcAJ]

Less is more.

Rich Courtney once asked me a question while filling my tanks at Cave Excursions East in High Springs. "Why do we even bother to shut down a leaking post?" What he meant by that was if we've planned correctly, the moment there is any problem with gas we should just be able to signal OOG and head toward the door.

We tend to overthink problem-solving in technical and cave diving. Another cave instructor and I became lost on a line in Manatee when my scooter quit. We were both trying to figure out the issue and referencing the guideline when we found ourselves getting the scooter going. We decided to continue the dive but we came to the end of the guideline. We somehow managed to get in a side tunnel. I started to lead out, but we never speed-matched the DPVs. I left him in the dust. I also spotted the outbound mainline and made a visual jump to it. Now, we not only had team breakdown, but we were on different lines out of sight of one another (and what if I was wrong about the line being the main exit out?). I waited for my buddy and saw him deploy his spool to do a lost line or lost buddy search. I signaled to him, but he didn't see my light. I fetched him and we exited. Eventually, we figured out we were sucked into the Milk Tunnel (siphon), that we forgot to match speed, and that it's too tempting to use a DPV to make visual jumps.

What was our goal when my SUEX XK1 quit? To go home. Why did we mess around with it and waste time? We should have just rigged for a single DPV towing a broken DPV exit and left. We would have had all day to fix it on the surface. Same with gas. As Rich Courtney pointed out, we should just get to the door and not waste time trying to solve manifold issues when we are most likely going to thumb a dive even after we get it sorted.

I'm not saying this is the solution. It is a possible solution. It's definitely a campfire or fill shed chat, but Rich had a good point to consider about just going home since we have the gas. And, the less time we waste, the more gas we have to get us home.

We’re getting off topic, but just abandoning viable gas and sharing air is needlessly putting all your eggs into one basket. Same with abandoning working scooters or not taking a moment to fix a scooter.

CAN YOU make it out? Likely. But there’s no sense in making a bad situation worse by not taking corrective action.

Getting pushed around into side tunnels or off the line happens to folks, but that just goes to show the importance of having one team member be the anchor (hand on line, thump pointed out) while the other sorts it out. Especially if it’s complicated and perception-narrowing.

RIP Rich tho.

 

[Endler's]

Were I ever to dive doubles, my isolator knob would be Vindicator style like this fellows:

YouTube Video by Dive Zone Scuba
I think they make diving safer.