UK diver dead - Truk Lagoon, Micronesia

[Kevrumbo]

There's nothing in the report regarding CCR malfunction, or witness to any missed pre-dive steps such as a pre-breath & sensor check etc.

Cause of Death: Drowning. Rule Out Exertion Hypercapnia (?) as precipitating event.

 

[KevinNM]

How about not doing a pre-breathe for at least 5 minutes?

Yes (though I've seen arguments that this isn't as useful as was thought), there is a very long list of things people have done or failed to check that have led them to die on a rebreather. You are basically diving an anesthesia machine, and you don't have an anesthesiologist in the water watching all your vitals ready to act if something starts to go wrong.

None of this would be involved if it was a medical cause, if doesn't mater how careful you are with setting up your gear if you get a sudden massive stroke or PE in the water.

 

[wedivebc]

How about not doing a pre-breathe for at least 5 minutes?

If you are referring to doing a prebreathe as a necessary step in order to activate the scrubber that has been proven false. It has been also proven that the 5 minute prebreathe cycle may not be sufficient to show a faulty scrubber. It is my practice and I encourage students to not do the prebreathe sitting idly on the boat but to put the loop in their mouth while gearing up and moving about. More CO2 production means more likelihood of exposing problems.

 

[Patoux01]

It is my practice and I encourage students to not do the prebreathe sitting idly on the boat but to put the loop in their mouth while gearing up and moving about. More CO2 production means more likelihood of exposing problems.

What if they do something stupid, like not having the O2 open? I prefer passing out sitting than moving around on a boat with 30kg on my back. Accident Analysis – Near Fatal 5 Minute Pre-breathe

 

[doctormike]

So, from what I can tell - he was on the surface (?) with his buddy, trying to clip on a bailout tank. I guess he then became unconscious which caused him to lose the loop with the DSV open and flood the unit, making it negative, right? Hard to tell for sure from the report, but if that's the case, that rules out hyperoxia. So the loss of consciousness could have been from:

1) Hypercapnea - implies an exhausted or improperly packed or installed scrubber, or a failed mushroom valve.

2) Hypoxia - O2 shut off or otherwise not feeding the loop.

3) Medical event at the surface


1 seems more likely, especially since there is no way of monitoring CO2 concentration in the loop.

2 seems less likely for an experienced CCR diver. Not that there couldn't be a problem with O2 supply, but you would think that he would have seen the PO2 dropping on the controller and/or HUD.

3 is always brought up when we want to minimize the apparent risk of the sport, and I guess it's possible that he just happened to have a stroke or a deadly cardiac arrhythmia at the moment he splashed, but that seems statistically less likely.


Will be following this one closely for updates. Sad.

 

[wedivebc]

What if they do something stupid, like not having the O2 open? I prefer passing out sitting than moving around on a boat with 30kg on my back. Accident Analysis – Near Fatal 5 Minute Pre-breathe

Not having the O2 open is a real danger, especially in a leaky valve (KISS) type system because a diver will open the valve (usually) as they enter the water and close it when they leave the water to prevent the O2 from leaking away on the surface. It has been know for divers to forget to reopen the valve after a surface interval (I have done that). If you are monitoring your PO2 as you are suppose to do at all times you should catch a drop in po2 long before you pass out. In fact during the pre-breathe you will most likely need to add O2 to compensate for loss in loop violume which would catch a closed O2 valve. You would have to make quite a few errors before you would pass out during a prebreather due to a closed O2 valve. I don't think that was anything to do with this accident though.

 

[AZNetEng]

As a new member Ive read quite a few of the A and I threads. When something like this occurs is there typically someone involved with the investigation that knows something about diving, the equipment, etc?

 

[PfcAJ]

As a new member Ive read quite a few of the A and I threads. When something like this occurs is there typically someone involved with the investigation that knows something about diving, the equipment, etc?

Total crapshoot. Sometimes yes sometimes no. Sometimes even manufacturer reps check the unit. Conflict of interest? You bet!

 

[doctormike]

Not having the O2 open is a real danger, especially in a leaky valve (KISS) type system because a diver will open the valve (usually) as they enter the water and close it when they leave the water to prevent the O2 from leaking away on the surface. It has been know for divers to forget to reopen the valve after a surface interval (I have done that).

I have done it too - shows the importance of a preflight check / prebreathe before every dive. I was sitting there wondering what was taking so long for the O2 to rise to the 0.7 setpoint. As it slowly drifted to 0.5 and 0.4 after a few minutes, I was thinking that there was a problem with the solenoid, so I hit the manual add valve and got nothing, which made it clear what the problem was. But I was surprised how long the PO2 stayed in breathable range with no O2 supply.

 

[AZNetEng]

Total crapshoot. Sometimes yes sometimes no. Sometimes even manufacturer reps check the unit. Conflict of interest? You bet!

Thanks @PfcAJ. I figured as much but didnt want to assume.