Minimising Rebreather Deaths / Fatalities

Mdemon

As DrMik/RichC/DW said, what the Hell's the point in having electronics if you then ignore them and do a sloppier job by doing it manually?

Your training is to let the unit handle the O2 and to monitor it doing so. So do it! Jeez, talk about adding unnecessary complexity for the sake of it! (1) Why not clip a handset in front of one eye using an old coat hanger? You'd have an even better idea of what your PO2 is doing then.

Maybe we use thicker hoods in the UK, but I only hear the odd firing of the solenoid. Most of the time I am busy doing the dive. What I have got time for is relentlessly checking my handsets. In other words, doing the basic stuff right.

If you are in the habit of checking your handsets regularly, there is no difference between running a unit mCCR and eCCR (monitoring-wise) except for your actual PO2 will be held steadier using the latter. I can think of more sensible ways of making Rebreather diving safer.

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If you are religous about monitoring your PPO2 then flying manually adds little, however if you are not then it forces the user to monitor their PPO2 - in an ideal world it would not be needed as everyone would always know their PPO2 (and the fact the leccies are working correctly) however it became blatantly obvious to me when doing this work that is not the case.

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PacketSniffer

But if one is religious enough to manually run their rebreather (to keep yourself alive), then why can't someone religiously monitor their PPO2 in eCCR mode?

With either method, the goal is to keep yourself alive. I just don't understand how anyone could be complacent on that duty.

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bgpartri

I think another factor in here is that people who do their first 100 hours on a manual unit get a very good "feel" for how the rebreather is supposed to work. They could be more likely to notice if it is acting weird.

If you start off automatic, I think it some people take a lot longer to get the sense of when things aren't normal.

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RichClark

Thats a very good point - i do feel that by diving my KISS i'm much more in 'tune' with my unit, more so perhaps than using a newbie using a eCCR. I would expect this to carry over, if i ever do move to a eCCR.

Cheers

Rich

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jmurba

Hi rich,

all of that has a Limit.

I've dived kiss style without alarms for long following what Gordon Smith was preaching years ago (alarms and automatic systems are lowering diver guard and are leading him to death).

For long I could show off saying with my kiss style i have never had less then .70 bars of o2 in my loop....

I recently jumped in my rib, switched on my gps, and arrived on a wrong dive site.

The viz bad (i am not used of that in Cannes), once at the bottom a tried the recognized the site, ans has it was not the one i thought it took me 15 minuted lingering at the bottom to realize that i was not where a tought.

Of course i lost my way and was preoccupied by the situation (necessity of finding back the anchor line beacause no one was on the rib)

For the first time in my life I must have spnt at least 10' without watching my meter......and as during this time I ascended from 45 m to 30m following the bottom the ppo2 went down to .60 bars, a ppo2 that i learnt cheking my meter after say 10' on anchor seeking at the bottom !!!!!

I don't have a lot of CCR hours (arround 300) but I relly thougth that it could not happend to me.....

The worst point of the story is that I have buitl a good metter that drives good and loud alarms and that I prfer not to use it cause the mark munro has mutch pleasant displays than my 2x16 lcd display that It is not pleasant to read : see the photos http://www.rebreatherworld.com/photo...php/photo/3488

Even if gordon was a fantastic Rebreather man I think now that even if some of us fly manually to master the machine , we need good and reliabl automatic systems either to inject o2 if there is not enough either to let us know clearly that there is not enough.

I think that using the automatic injection system as a back up, is a good idea, but why don't you add your ECCR a kiss valve to lower your task load ?

regards

jean mi

Tom Rose

Hi Guys,

The original thread has somewhat lost, but the discussion has been interesting to a lurker. I guess I have to weigh in, and thats a lot of weight.

It seems to me that many of the more recent comments have focused on issues from specific types of diving and system comparisons. I personally think that the first article did a great job....

Many of you guys dive deep, dive long, dive under conditions I no longer consider exceptable. You are looking at it from a narrow view....and your points properly reflect that view...

IMHO shallow dives to 25 feet or less with a pure oxygen rebreather...no meters except a simple depth gauge is safer than any OC....Note the qualifiers in my statement. Thus, I have to respectfully disagree with the notion that OC...which I dive about 70% of the time is safer. No moving parts, light weight, no decompression...and availability of lots of great diving on shallow reefs around the world. Over the years I have had more mechanical problems with OC...

So my thesis is that we must consider why we want to use a rebreather....My view is based upon my usage.

Most of my dives are less than 140 feet....
Nothing but water overhead or a short stretch of shipwreck....
And I bet if you surveyed the group you might find that a high percentage dive under similar conditions.

I dive ccr mixed gas during the week to get close...really close to critters...I love to have them climb up on my arm to clean the hairs off. It makes video a dream and stills too.

I like a 90 minute dive without having a dry mouth or to get as cold.

My fully loaded rig for two hours does not even weigh 30 pounds....

On the day before I fly out, I only dive a rebreather....stay less than 40 feet and decompress faster than the guys in the bar overall....with my long time in the shallows at the end of the dive....

On the day I fly out, I sometimes get in as much as two hours on pure O2 in the shallows while other people are waiting to get home....a quick change of clothes...dump the scrubber....throw everything wet into a bag in the box...and away we go.

And in addition to that light weight rebreather, I carry a spare air. I am comfortable that I can claw my self back to the surface safely.

So I too look at it from a narrow view of my diving practices

I guess I am saying while there seems to be some disagreement, it is based on how you dive....

Regardless, the article is fantastic for getting you starting on the right road for yourselves. This thread has been great.

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Dave Sutton

It flashes *when the solenoid is commanded to fire*, IE: When is *should* fire. If it's been isolated off, it'll still be "under command to fire" by the pod, so a blue LED then means *push manual add*.

Sort of a nice feature.

Dave

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babar

When I took my MOD 1 on the inspiration, my instructor made us fly manually for the first 3 days of the course,in order to build up the habit of checking the handsets every minute. It was a pain at the time, but I think it was a good approach, forcing us to develop that habit. The 4th day on auto was a breeze by comparison.

Of course, now, I just dive my KISS, so am on manual all the time.

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Tom Mount

Hi stuart
As I think this is very important read your excellent article and made some comments in red some wil give a different not better or worse approach than you would do- but overal agree except I'm a great beleiver that if one practices and know the unit they can usually take sanity breaths and fix the problem other than CO2 and full floods- and of course inaccurate cal. then go back on loop[ increasing the survival probability- but to do so must have the training - understanding of unit and experience to validate various procedures
Minimizing Rebreather Fatalities

We can minimise that possibility by following some easy rules:

1 – Never ever dive when there is something wrong with your unit. It does not matter what that fault is, it will start you down the incident pit. If it is not working 100% then do not start the dive – call it before you get wet.
This is always a big problem with many divers and most likely has contributed to accidents

2 – Set your equipment up consistently (fresh sorb every deep dive!) – I believe the only way to do this is to follow a written checklist that you sign off every time (In my opinion it is too easy to click through electronic checklists). We have all heard of people who died without switching their unit / O2 on – wouldn’t have happened if they had a checklist they followed religiously. Consider laminating your checklist for a final run through before you jump in.

Excellent suggestion- should be taught in most course but is often abandoned by divers once out of training


4 – Test your cells before / at the start of every dive and ensure they can read at least 20% higher than the PPO2 you intent to use to complete the dive (gives you a safety margin). You can do this in a number of ways:

• A pressure pot you can put your units head in.
• The device Ron Micjan makes to test cells
• Or my favourite combine it into your bubble check at 6m. At 6m I stop we inspect each other and I do an O2 flush and make sure my cells all get over 1.55ish and I then I can continue my dive on my usual 1.2 – 1.3 ppo2 and feel fairly happy.

Agree with the suggestion although not practical for many divers- I over pressure to check linearity then at 40 feet every third dive flush with o2 (during ascent not descent) if unit reads 1.8 or higher I know my sensors are tracking- then flush down with dil and continue ascent- Joe Cinteli has a system for over pressure testing also but do not think it is for commercial use. As we do fast drops on wrecks here such as 1 tpo 2 minutes to 160 to 200 fsw- the 20 ft check on descent is not doable for S Fl deep wreck divers
5 – Carry bailout and know how to use it / practice regularly. I am not going to go into a debate on what bailout is best for you, just have enough to get up. If you don’t have bailout and something goes wrong (Murphey anyone) you will die.


Would expand this to say practice ALL emergency routinely and understand bailout planning also practice switching bailout bottles with your buddy

6 – If something goes wrong on the dive with your Rebreather, it does not matter what it is, bailout and call the dive. Do not try and go back on the loop do not try and continue the dive bail out, surface and live to dive another day.

Due to deeper dives and cave diving would disagree here- if you know for sure what the problem is such as solenoid stuck closed or open – you can go back on the unit and control the po2- But agre4e that dive is to be aborted at this time

I agree if you are not sure of the problem then stay off the unit- Personally in all my years of CCR diving I have always been able to take a sanity breath and identify the problem and go back on the loop- including a failed open solenoid with instant 3.5 po2 took lots of flushes but did get back on unit and exit the cave on unit The only time I have had to stay off loop was due to co2 issues

I recommend you read the Tek cCR manual put out by IANTD it covers emergencies in depth


Take note of this – do not ever head for the surface if something goes wrong. You bailout out then you ascend.

Amen

7 – Dive in a buddy pair and stay together! If one person calls the dive you both call the dive. If somebody has an issue you need to be near enough to help them straight away. This I am sure will be contentious but in my research I have found over 5 incidents where people survived as their buddy brought them up, several where people died as there was no buddy pair (grey area) or the buddy pair split up and only one where it is strongly suspected that both people died as a result of one buddy getting into difficulties and causing the death of both of them.

And many cases where they died in spite of a buddy- point is dive with a buddy but be capable of saving your self as on CCR more so than any other piece of gear in diving if the diver does not identify the problem –correct it or get off the loop the buddy cannot prevent the consequence- So do not become buddy dependent and always dive with a buddy who like you is self sufficient then you have a true buddy team and one that can survive

This is an individual choice and I would urge you to discuss it with your buddy and your family but I strongly believe that diving in a buddy pair significantly decreases the chances of being involved in a fatal incident.

your unit manually using the electronics as a safety net. I strongly believe that anything man made is not perfect – we can spend billions on developing electronics be they for space ships, airplanes, rockets or nuclear power stations and we all know they go wrong and cause fatalities – a fraction of development cash is spent on Rebreathers compared to the above so let’s use them as a safety net.


For those who would argue why have electronics then lets qualify this with do the fine control of the unit as manual such as maintain the po2 etc say as 1.2 and set the set point at 1.0 to 1.1 so you are relying on the electronics as back up – but are using your skill and brain for control- this gives you the advantage of both worlds
I was unable to identify a single fatality that occurred when a unit was being flown manually.
In theory I agree- but not sure how we identify if people are diving manual or set point control – so I think the statement is stretching it a bit- But I would say a manual control as defined above makes for a lot safer diver

The list of 10 above is not designed to be an exhaustive list of how to dive your Rebreather safely nor does it guarantee to keep you alive, however they are the top 10 lessons I believe can be learnt from my recent work of examining fatalities on Rebreathers.

Panic

I feel I also need to spend a moment talking about Panic – it kills.

At the most basic level if your rebreather ceases to function and you panic and do not bail out you die. Where as if you do not panic and you bail out you live.
Panic is not staying on are getting off the unit- panic is a behavior that will kill you regardless of on or off unit-

And I personally would bailout long enough to do a sanity breath – check the system and if I recognize the problem go back on loop and I think live longer as I still have surplus bailout gas if needed

I need to live, this means I must not panic, to help me achieve this I practise my survival skills and envisage how I would deal with panic inducing scenarios.


Great and combine with visualization of all situations seeing your self react calmly then again always practice- I ruptured my round window in Sept and am just getting back in the water so my first few dives back are just practice and more practice so all my emergency skills are up to par

I have 3 scenarios I think about, practise where I can and visualise how I would deal with them to hopefully stop panic.

Scenario 1 – Something wrong with my kit. I bailout to my stage via open loop if possible. I signal my buddy if they have not noticed (I am sure they would have) and we ascend staying in very close contact.

Just avoid open loop if a co2 problem exist unless the dil ad is direct into the divers mouth without passing through the canister- it is good for many things such as electronics failure if you are not comfortable with SCR

I hope that this article has been useful to you and will help ensure that you do not become a statistic, it is not designed to be the definitive guide and I am sure that many other Rebreather World members will be able to contribute on how we as individuals can dive safer. To discuss this article please cl

I would add all emergencies to your visualizations and rehearsals
The old saying use it or lose it is very true and especially to doing emergency skills that should be practiced until they are in your muscle memory and then repeated to keep them in muscle memory

and thanks for the article it is well done and you will most likely survive th3e situtations that will happen on dives someday iif not already due to your atitude and on going personal training - of your skils- and reactions

One big thing on cCR everything one is trained on wil happen at some point if you dive CCR enough and everything that can happen is easily managed if you folow the though processe such as presented in this article- this kind of thinking makes one a survivor
Tom