Are Rebreathers Dangerous? - Closed Circuit Rebreather Accidents

Find out about different types of rebreather diving accidents and how to avoid them. Featuring the Choptima rebreather by Dive Rite.
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Featuring PADI Course Director Aitor Diaz at the Dive Ninja Expedition office in Cabo San Lucas, Mexico.
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In this video we cover:
Are rebreathers dangerous?
What kinds of accidents can happen?
How do you respond?
Can you help your buddy?
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[@AzulUnlimited]

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[@Teampegleg]

It is true that human error is the primary cause of CCR fatalities, the reason why rebreathers are seen as dangerous is because many of the failure modes are completely silent and a very short period from we have a problem until unconsciousness. Like the Hawaiian fatality and the one we had here at Ginnie two years ago, they probably had no clue that they were going to die until they found themselves in the after life. While most failure modes and errors in OC outside depth violations are quite obvious. And you likely have a chance of noticing the problem and taking some sort of action. IMO that is why rebreathers have their reputation. It doesn't help that lots of CCRs are poorly designed. "Let's put the DIL and O2 MAVs on the same block with no real difference between the buttons, what could possibly go wrong." "Let's build a CCR where if you want a HUD that requires a complex and flaky arrangement to hook into the cells." Add into the mix new divers that quickly went to CCRs and are doing deep hypoxic dives but haven't built up their OC bottle management skills, so when they have to bail out swapping tanks it a painful possibly fatal process for them.

[@AzulUnlimited]

All excellent points. Thank you for sharing

[@cavediver2579]

I have several hundred hours on a Kiss Sidewinder. I am a cave diver and mainly dive CCR. There are really only 3 failure modes all relating to the gas we are breathing. Hypercapnia, Hyperoxia and Hypoxia. The last two can be avoided by the cardinal rule of CCR diving, and that’s know your PO2, my unit is manual and I chose that because it forces me to be more attentive to my unit and what is going on with it, AND with me as a diver. We know what we feel like normally, we know how we should feel on a dive, etc… if anything feels off try and diagnose it and fix it, this may mean bailing out, even if just for some sanity breaths. I feel better breathing OC I may be getting some CO2 break thru. My point is that you have to dive the unit with the thought process that you will have a failure at some point. Stay on top of it and it won’t just kill you without you knowing something is wrong. Get the right instructor and training and a CCR is as safe if not safer in some environments than OC. Of course there are mechanical failures, but all of those are why you carry bailout gas.

[@Fdzzaigl]

Personally saw 3 accidents, 1 deadly during covid when people started diving a lot in Belgian quarries. One extremely experienced instructor of my club died a few years earlier due to forgetting a valve after getting back in the water after first getting out when losing a fin at the start of the dive. I'm slowly getting interested in rebreather but be damn careful with them things. I'm always a bit critical of certain techies pushing toward rebreather diving. It's not for everyone.

[@AzulUnlimited]

I completely agree. Accidents are always terrible. Be safe out there

[@scubaeb]

Just saw this. We are going to Socorro end of March. Can't wait to see your report/video! We are already so excited. What boat are you on?

[@AzulUnlimited]

I haven’t gotten the response I was hoping for this trip, so I’m not sure I’ll be there… it was going to be on the Nautilus Undersea… maybe I’ll get people for a trip in 2025 🫠 enjoy yours though! I want to hear all about it!!

[@pinnacledivingco]

5:30 into the video: HUD's are backup systems only, and should be treated as such for a few reasons. The first is "Orientation Attention" which is tied to "Unconscious Selective Attention". Your brain picks and chooses what information to pay attention to ("Discovery Attention") based on a few variables such as immediate needs, perceived threat, actionable requirements, etc. Unfortunately, this means you really only ever "pay attention" to 10% or less of the world around you. The HUD on the loop in front of your eyes is the same, and your brain will choose to ignore it simply because things "go right" greater than 99% of the time. Dive after dive after dive, you complete the dive successfully, and the HUD, while flickering in front of your eye, will disappear from your vision entirely (despite the flickering LED's), simply because your brain will purposely begin ignoring it as not worthy of its attention. The second reasons is "Retinal Rivalry". This is a subject all aviators are trained on, but applies equally to divers, and to which I discuss in my book and course on Spatial Disorientation for Divers. Essentially, if you have an object in front of one eye, and nothing in front of the other, the eyes will begin fighting back and fourth for visual dominance, up until your brain makes a decision to focus on what it thinks is more important. At the end of the day, thanks to the first issue mentioned, this means the ocean/landscape/object(s)/buddy(s) out in front of you will win, and that HUD with the blinking LED's will lose, slowly disappearing out of existence before you realize it during the early stages of the dive. This is exactly why I choose to stick to using a Petral2 on my arm instead of a NERD2 on my loop as my CCR Unit's controler.

[@AzulUnlimited]

Thanks for the info. Aitor mentioned that it’s good to use the hud as a quick visual check to verify that everything is reading correctly. He only mentioned using the counting method as a last resort when dealing with other failures.

[@pinnacledivingco]

@@AzulUnlimited Yes, that is typically how HUD use is taught. Though, it demands consistent, meaningful, and intentional practice, even on every dive after certification. Without these, the HUD quickly slips into the blind spot, and many in the past have gotten into trouble when all else failed, and they never once looked at their HUD to notice a problem even existed.

[@EdwardSouthworth]

i will being doing two weeks in the sea of cortez aug 7-17 2024. ill be bringing my KISS Classic with me!!

[@AzulUnlimited]

Awesome!!! Sounds lovely

[@davidb5195]

I will do ccr/rebreathers potentially next year. Currently, I am getting ready for oc technical diving courses.

[@AzulUnlimited]

Heck yeah! You're gonna love it.

[@BrandonSchmit]

When practicing bailing out, doesn't water get introduced into the mouthpiece even though the valve in front is closed off? In that case, just a small amount of water would be introduced into the system upon rebreathing again? Is this why there are water traps in the system?

[@AzulUnlimited]

There’s a hole in the mouthpiece where you can purge that water before opening the loop. It’s not a lot of water.

[@E_Clampus_Vitus]

That water in Cabo is ridiculously warm.😂

[@AzulUnlimited]

Haha it’s not too bad

[@Yggdrasil42]

Look at that pro intro!

[@AzulUnlimited]

Thanks so much!

[@willsmooth45]

What I love about my RD1 rebreather is it’s FULLY modular and repairable this unit doesn’t seem to be as easily repairable also it’s 1/4 the cost 😅

[@AzulUnlimited]

I’ll have to check that out!

[@padraicmcgraw]

@9:24 is that scene from zoolander where they want to get the files out of the machine but it is sorb in a canister.

[@AzulUnlimited]

Omg yes! 🤣😅 that was totally it

[@EdwardSouthworth]

I dont see the sea of cortez trip

[@AzulUnlimited]

My Baja trip is sold out but Komodo is still available!

[@nathanmesser56]

I'm a rebreather diver, so I'm not anti-rebreathers by any means. However I think the attitude that it's safe because deaths are caused by human error rather than unit failure is flawed (and it is a very common attitude among rebreather divers). If you making a minor mistake is potentially fatal, then it is more dangerous, as we're all human, and we all do make mistakes. I think that attitude is actually holding us back from making rebreather diving safer, and is a way of avoiding confronting the fact that it is more dangerous. RF4 was sobering, and it taught us that rebreather fatalities are still occuring at about the same rate they were 10-15 years ago, whereas the general opinion in the community was that it had gotten significantly safer. Telling people to simply be more disciplined is unlikely to get us the step change we all want in making it safer. Personally I think a lot is in the unit designs. I'm always amazed for example that some units don't have an audible alarm (mine has a buzzer, aka "an attention getter").

[@AzulUnlimited]

Fair enough. I just shared what Aitor was taught during training. Maybe the message needs to be changed for students 🤷‍♀️

[@nathanmesser56]

@@AzulUnlimited For balance I should say I do love my unit, and everything you've heard about fish not being scared and getting close is true. I've had huge schools of sand eels swarming round me and pollock hunting them as if I wasn't there 🙂

[@mikesbigadventures194]

Rebreathers are great because you have lots of time to work through a problem if you need to.

[@AzulUnlimited]

Exactly🤙 thanks for watching🙏

[@timgosling6189]

You say that many rebreather accidents are due to human error. This is true, but remember that rebreather divers tend to be already highly experienced open-circuit divers. They are generally not stupid, even if with 20/20 hindsight they appear to have done something really dumb. In the sad case you mention the guy was a Navy diver, a qualified professional, undergoing his final CCR training. So the important thing is to understand that the human brain is an integral part of your dive equipment, and know what its common failure modes are, as well as a the technical failures we tend to concentrate on, say with the scrubber or electronics. As I understand it, CCRs are now pretty safe but there is more knowledge and new skills to master and the diver needs to be firmly in the zone, and aware of potentially dangerous distractions or mental pressures. For instance, as Aitor says, in the real world you wouldn't work through your checklist while doing a piece to camera. Gareth Lock, one of my old colleagues when I worked for a living, has made an excellent film that includes some great points: kzbin.info/www/bejne/fnaTlGqtrLmnjbM

[@davidb5195]

Yes you have to use your brain and decide what the appropriate action is based off of what the machine is doing.

[@AzulUnlimited]

Thanks for watching 🤙

[@Yggdrasil42]

Well said. The machines are quite reliable. Humans are not. It's worth doing the Human Factors In Diving training from Gareth Locke. It's a very worthwhile course for all divers but especially for CCR divers. It teaches you that accidents don't come from a single mistake but are a combination of factors and how to deal with that.

[@AzulUnlimited]

@@Yggdrasil42 Thanks for sharing that resource!

[@BrandonSchmit]

So not only do you need an expensive rebreather, you have to have two really expensive computers as well? That's an additional $3.5K or so! If you bought two Petrel 3's.....

[@AzulUnlimited]

The systems usually come equipped with the computer controller so you *just* need one more😅

[@ChrisShaferKTM]

The rate of rebreather incidents and fatalities per hour of diving is significantly higher than open circuit. The chance of breathing a gas incapable of supporting life on open circuit is much much lower

[@AzulUnlimited]

Which is why you need good training and check lists. Trust me, I get it, but I also understand why people want to dive them

[@AegeanEpiphany]

In 17 mins - with the dangerous assumption that all those ending up on a rebreather (for whatever reason) are the right people, in the right circumstances...

[@AzulUnlimited]

I think a lot of people are interested in them, so why not talk about it?

[@whitter86]

"Are they dangerous?" *proceeds to have a light hearted conversation about death* I'd say they are. 1 in 100 die using a rebreather.

[@AzulUnlimited]

I would say the conversation was just us being realistic. Scuba diving has inherent dangers and yes, rebreathers are more technical meaning there are more places for error and accident. I still think that using them appropriately with the right training and conservative practices is safe

[@sadagat]

I was out as soon as I heard human error . . .

[@AzulUnlimited]

how so?

[@sadagat]

@@AzulUnlimited, attributing the cause of a diving accident to 'human error' is practically useless. That term is a bucket that we can put all the different sorts of performance variability into without understanding what we can do to prevent future events. Adverse events like accidents, incidents, and near-misses are the outcomes of interactions within a system, and we can’t deconstruct the problem to single failures of individuals, hoping to ‘fix’ them. While ‘human error’ might be an easy bucket to throw the variability of human performance and its associated outcomes into, the attribution rarely improves safety or performance because it doesn’t look at the rationale behind the performance or the context associated with it. Gareth Lock, 2022

[@Frindleeguy]

But it's user error. It's not equipment failure. Those are the buckets most rational people are using to determine risk factor. That's super common sense, and makes sense to everyone but you ;) @@sadagat

[@lyndycranson6786]

I understand that rebreathers can be safe. Saying that I have known several very accomplished divers that have died on rebreathers. My choice is to continue to dive OC.

[@AzulUnlimited]

Totally understand. Accidents are horrible and I’m so sorry you’ve lost friends to that.

[@jonnieinbangkok]

I'm sorry but in my opinion, rebreathers have too many service points compared to open circuit scuba diving, which makes that many more points where even a consciousness diver can slip up with fatal consequences. There is a place for rebreathers in the military and maybe certain types of scientific or commercial diving but not in recreational diving. And almost whenever I read about a dive fatality, the person was on a rebreather. And the units themselves are so hinky, you need open-cir until bailout tanks with you anyway (that be like open circuit divers being required to also have a rebreather.) Why even today, I walked into a shore dive without my fins and I'm a Divemaster and a very consciousness diver 😅😅😅

[@AzulUnlimited]

I get it! Rebreathers aren't for everyone, but it's cool that tools are getting better for all the different kinds of diving we want to do.

[@alaincaspar2148]

Because you may be a very consciousness diver but without a written check list you are going to forget things one day (like your fins this time). That's why they made written check lists in aviation and for CCR. I admit it is a bit cumbersome for most divers

[@AzulUnlimited]

@@alaincaspar2148 Totally, which is why most divers will never get into CCR, but it's nice to have the tools 🙏