Stage Dropping

[rjack321]

Exactly. We do multi stage, multi gas dives all the time, and every switch gets verified. I'm kind of shocked that this isn't SOP in caves as well.

It is, but people get careless when they "know" all the bottles are the same or they thought they dropped the correct bottle and so they don't have anything on them deeper than its supposed to be etc. I doubt the RB80 switchblock helped this situation because its not easy to see which stage is being breathed from an LP hose out of the diver's armpit. But someone should have said, "hey what is that 70ft bottle on you doing down here >70ft???" at some point. Maybe they did or ??? I pray for a full accounting so we can learn from what happened.

I argued so vehemently against UTD's silly "don't bother to mark bottom stages" rule exactly because on my boat there very well may be multiple bottom stages aboard with different mixes in them for different dives or different buddies and everyone needs to be verifying every gas breathed every time. Even with the markings it seems the protocol broke down in this case. This is not the first instance I have heard of where 3" MOD letters were mentally glossed over or not religiously followed (which seems to be the case here).

 

[limeyx]

I dont think this is correct. Those switches *should* be verified, including at the start of a dive before descent. If the info we have is correct, then it seems a Richard stated that it was human error in that they were not verified in this case that caused the incident.

Also, as pointed out, with a RB, it can be harder to see whats being used as the hose doesn't go direct to the mouth, so that makes it doubly important to show the bottle and the hose before you plug it.

Definitely a sad reminder not to let complacency set in.

Verifying a stage drop on these kinds of dives cannot be a "mechanical" check of the MOD as bottles probably are dropped for all kinds of reasons (i.e. it might be quite valid to drop a 240 bottle at 70 for later back-gas breaks, or maybe someone else is going to come collect it later --- for that, only clear briefings and discussion of team goals can probably be effective)

 

[cavemn]

Exactly. We do multi stage, multi gas dives all the time, and every switch gets verified. I'm kind of shocked that this isn't SOP in caves as well.

Who do you use to verify in a silt out? Or Solo?

I can't even see the side of two bottles on my side mount rig. They ride above and between my backgas and my harness. All I can see is what goes in my mouth. So, I practice my procedure which entails verifying markings before I even get in the water.

Your mileage may vary, Not available in all areas, See fine print for details

 

[down4fun]

This is no different than someone labeling the tanks incorrectly, forgetting to charge batteries, not making sure you have everything. When you fail to do something correctly in pre-dive, expect to fail during the dive.

true, humans make mistakes. It's why surgical limbs are marked yes and no with permanent marker, its why 2 RN's verify blood before a transfusion. so in diving having someone else double check only helps to ensure that it's caught during the pre-dive phase.

I screw up my reg setup pre-dive then it's my fault, nobody elses. If I don't label my tanks and according regs (I remove the tape after dives so I'm forced to check and label) then it's my fault. Your buddy/team is there to help you not babysit you. Only person looking after me is me.

If you had quoted my whole post you would have seen that in the last line I say "and though ultimate responsibility lies with ourselves it doesn't hurt to police each other too."

 

[TSandM]

It would be interesting to know whether the WKPP verified switches on and off bottom stages. I was specifically taught in Cave 2 that this was not necessary.

 

[Cave Diver]

In a slightly off the wall tangent, has anyone ever considered marking the MOD on the bottom of tanks in addition to the side? Sometimes with multiple bottles or single file diving the markings may not always be visible. Marking the bottom of the tank also may provide an opportunity for a secondary check.

 

[Dive-aholic]

I'm never going to be color coding regs or anything else. The damn bottle has 3" high numbers on the side. Those numbers must match the analysis before the cylinder leaves my garage. Those numbers are the only constant which conclusively links the analysis with a safe depth to breath it at.

Until you can't see those number because the cave you're in is that silted out. It can happen. Ask Lynne and Peter.

I agree. Using identical regs on all my bottles forces me to verify the markings on the bottle, rather than rely on a visual or tactile cue that I'm on the right gas. I'm not saying those of you who choose that method are being complacent and not checking markings, but I can see how it might become easy to do so.

Well, my AL40s are as follows - 100% are shot blast with the number 20 on them; 50% are yellow with 70 on them. I still rely on different regs for the times I might not be able to see those colors or numbers. But when I can see them the bright yellow color and the dull shot blast are usually enough to tell the difference.

As for my AL80s - 100% are shot blast with the number 20 on them; 50% are blue with 70 on them.

Also, my deco cylinders are the only ones rigged up with standard stage rigging. Easy way to differentiate when you dive sidemount and carry stage cylinders on top. Those cylinders are rigged very differently.

Finally, AL80s used for trimix are shot blast with SM stage rigging. AL80s used for nitrox are black with SM stage rigging.

If I place the wrong regs on the wrong cylinders, then I really don't need to be diving that day because I'd really have to have my head up my a$$ to make that mistake.

 

[jjones9527]

If I can't see the bottle markings, I don't use it, period. Relying on an identifying feature on anything but the bottle makes it that much easier to screw up. There was an instructor up here who used to rely on the "right rich, left lean" methodology for identifying his gasses. Worked fine until he strapped them the wrong side one day and went on O2 at 70ft.

Every system is fallible when complacency sets in. Reducing the things that can be over looked goes a long way in lowering the odds.

 

[rjack321]

It would be interesting to know whether the WKPP verified switches on and off bottom stages. I was specifically taught in Cave 2 that this was not necessary.

I'm sorry but you misheard, DR is 100% wrong, I don't know what happened. Stage switches are one of the moments of greastest screwup-age. People go "OOG" at stage switches and lordy know what else nevermind switching to the wrong gas.

 

[Dive-aholic]

If I can't see the bottle markings, I don't use it, period. Relying on an identifying feature on anything but the bottle makes it that much easier to screw up. There was an instructor up here who used to rely on the "right rich, left lean" methodology for identifying his gasses. Worked fine until he strapped them the wrong side one day and went on O2 at 70ft.

Every system is fallible when complacency sets in. Reducing the things that can be over looked goes a long way in lowering the odds.

Having tactile differences is not complacency. And you're response about not using the cylinder tells much about the environments you dive in. It's not unusual for me to be in a zero visibility environment. While I haven't dealt with it at the point of a switch to a deco cylinder, it's not unlikely for me. It's also why I make my secondary tie (cave diving reference) at 20' whenever possible. I then know when I am at the secondary tie off I can switch to my angled reg and do my deco even when I can't see anything.