Waterford Garda dead - County Wexford, Ireland

[helodriver87]

Whether he was aware of the malfunction or not, it’s still a malfunction. How can you then say it was a user error. Just because someone fails to bailout doesn’t make the reason for the bailout their fault.

Because that should be survivable. You're taught exactly how to respond to a situation like that when you learn to dive CCR. From the beginning I've said it was mechanical failure compounded by user error. Because the vast majority of accidents include human error as a contributing factor. Very, very rarely can you accurately say it was totally unavoidable. There are lessons to be learned from a human factors perspective here that you're trying to discount.

 

[John the Pom]

As an engineer, I am deeply uncomfortable with a system where the safety philosophy is: "When there is a fault, an alarm will sound. The first time the user fails to respond correctly to that alarm, the user dies." Because a system like that will inevitably kill its users at a steady and fairly predictable rate.

 

[jborg]

How noticeable are these alarms? In a thick drysuit with hood I don't expect vibration and audible alarms to be very reliable. So a blinking led somewhere in the normal FOV and a message on the dive computer (which may not be in your FOV)? A freeflow event on OC is at least fairly noticeable. Stall warning in an airplane is quite noticeable.

 

[Celt]

As an engineer, I am deeply uncomfortable with a system where the safety philosophy is: "When there is a fault, an alarm will sound. The first time the user fails to respond correctly to that alarm, the user dies." Because a system like that will inevitably kill its users at a steady and fairly predictable rate.

That’s exactly it, and because divers are not reacting quickly enough the user is been blamed.

 

[telemonster]

How noticeable are these alarms? In a thick drysuit with hood I don't expect vibration and audible alarms to be very reliable. So a blinking led somewhere in the normal FOV and a message on the dive computer (which may not be in your FOV)? A freeflow event on OC is at least fairly noticeable. Stall warning in an airplane is quite noticeable.

Unfortunately the Shearwater electronics used on CCRs lack any audible (beep) or mechanical (vibrate) alert when things are in the red. The HUD is in your FOV, and should be blinking red but I wonder if it's possible at large hours to grow accustomed to it and miss it.

No idea why Shearwater left out other signaling. Control systems that came before it like the Hammerhead would vibrate the the HUD if critical messages were on the controller. Not blaming Shearwater, their products are some of the best out there but I wonder how many deaths would have been avoided had the controllers signaled outside of display messages.

Did this diver mix the o2 tank up with the dil tank?

 

[helodriver87]

That’s exactly it, and because divers are not reacting quickly enough the user is been blamed.

News flash, if you don't react quickly enough to most breathing system failures underwater, you'll die. And I'll reiterate it One. Last. Time. Toxing isn't instantaneous. He likely had a few minutes to recognize the issue and take a two second corrective action.

 

[helodriver87]

How noticeable are these alarms? In a thick drysuit with hood I don't expect vibration and audible alarms to be very reliable. So a blinking led somewhere in the normal FOV and a message on the dive computer (which may not be in your FOV)? A freeflow event on OC is at least fairly noticeable. Stall warning in an airplane is quite noticeable.

The HUD is the standard. It uses an LED blink system that kinda fades into the background until it changes pattern. It's very noticeable, but can get washed out by direct sunlight, which is why a crosscheck with your controller is important. The HUD will blink frequently and bright red directly in your FOV and your cell readings on the controller will turn red and flash. It's very hard to miss if you're regularly checking your PO2. If you're very distracted though, of course you could miss it.

 

[helodriver87]

As an engineer, I am deeply uncomfortable with a system where the safety philosophy is: "When there is a fault, an alarm will sound. The first time the user fails to respond correctly to that alarm, the user dies." Because a system like that will inevitably kill its users at a steady and fairly predictable rate.

I don't see how that's much different from a free-flowing reg. You have to respond correctly on the spot, whether that's a shutdown, OOG signal, or surfacing. Fail to respond to the first indication, you drown.

 

[Colliam7]

Rubbish, it isn’t user error if the equipment malfunctions.

I think that the point that posters are making is that there may be technological failure, but the proximal cause of ultimate outcome may nonetheless be user error.

There may be failure of technology, but users can still react and salvage the situation. Several posters have made reference to aviation, such as comments on how prominent the sound of a stall horn is. Yet, even though stall warnings are prominent, pilots still mange to stall airplanes.

One extraordinary example of the relationship between user error and equipment failure, in which equipment failure was the initial problem, but user error was the proximal cause of the tragic outcome, was Air France 447. The equipment failure was pitot tube icing. As a result, the pilots lost airspeed information, and the autopilot turned off. Notwithstanding that issue, the aircraft was still very flyable - it remained entirely airworthy - the control surfaces were fully functional, the engines remained capable of producing full thrust. But, the pilot flying the aircraft (right seater) stalled the aircraft, by gradually pulling back on the yoke, probably out of anxiety, perhaps complicated by distraction. According to the investigative reports, the stall warning sounded prominently some 75 times over the next 4+ minutes, as the pilots literally flew the aircraft into the ocean. The proximal cause of the accident was user error, not equipment failure.

 

[uwxplorer]

I think that the point that posters are making is that there may be technological failure, but the proximal cause of ultimate outcome may nonetheless be user error.

No. My point was that there can be NO rebreather failure but the succession of errors by the diver may lead to the diver toxing. I know at least one close and personal example.
Our Irish friend doesn't seen to believe that this is possible. I would invite him to open up his mind to the endless subtleties of human psychology...
I also pointed out that you can die of oxtox on OC if you breath the wrong gas at the wrong depth and there again, everything might otherwise work just fine, but use error will result in death. This has happened not so long ago, when a diver declined to analyze his gas before a cave dive and toxed out.