Great video on the "normalization of deviance" error

[BRT]

Basically, if you are taking a calculated risk, calculate it properly.



Bob
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I think that advocating unsafe and dangerous practices is both stupid and foolish. That is why I don't tell people to do what I do. Dsix36

But a calculated risk may and eventually will end up badly, if you live long enough to keep taking the risk. We have to accept a level of risk.

 

[Bob DBF]

Quote Originally Posted by Bob DBF View Post
Basically, if you are taking a calculated risk, calculate it properly.

But a calculated risk may and eventually will end up badly, if you live long enough to keep taking the risk. We have to accept a level of risk.

Yes, a calculated risk is a risk, however the level of risk taken is dependent on your assessment of the dangers and your aversion to risk. Just breathing compressed air under water is a risk many will not take.

I do agree with Mike Mullane's thesis: "Normalization of deviance", in that calculating a risk based on your experience, rather than the facts of the evolution, will not give a true picture of the risk involved. As an example, say I solo dive regularly to 160' on air with a pony which I never have used on the dives. I now decide I do not have to carry the pony because it has never been used. My calculation of the risk is flawed because I base it on my experience rather than the possibility that something goes wrong and that "extra" air is needed to avoid a CESA or for a deco obligation. My risk is increased, and I don't know it, because I overlook some dangers inherent in this type of diving.

After 50+ years of diving I figure my risk assessment has been pretty good, others may argue that point.



Bob
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That's my point, people, by and large, are not taught that diving can be deadly, they are taught how safe it is, and they are not equipped with the skills, taught and trained to the level required to be useful in an emergency.

 

[Abdullah]

I agree with Mullane's thesis: "Normalization of deviance" leads to increased risk. I don't completely agree with his example. Not completely. My understanding is, Challenger's last flight occurred on a day that started off much, much colder than with any previous space shuttle flights'. These very cold temperatures compromised the ability of the booster rocket O-rings to quickly and sufficiently seal the rockets' joints when pressure built up inside the booster rockets, which led to the breaches and the catastrophe. It was the unprecedented, excessively cold temperature that is believed to have been the direct cause of the catastrophe.

If Challenger had flown, instead, again and again at this very cold temperature, with the catastrophe eventually "catching up" with NASA, then Mullane's using the Challenger catastrophe as an example would make more sense (to me).

Physicist (Nobel laureate) Richard Feynman's book ("Surely You're Joking ...") is worth reading regarding all this.

(A chapter of my 1991 statistics PhD dissertation pertains to this disaster. Specifically, a Bayesian statistical approach is employed to show that the likelihood of booster rocket O-ring failure increases dramatically with decreasing start temperature.)

Safe Diving,

rx7diver

The normalization of deviance was in NASA management decision making. They had allowed their decision process to deviate outside safe limits for manned space flight. The cold weather was a trigger that caused a particular catastrophic failure. It's not necessarily the only catastrophic failure the management process was vulnerable to. It was merely the one that happened first.

Translate this to diving in a basic example. BWRAF - Always performing these basic checks, especially with your new instabuddy, can resolve the most likely failures well before something becomes an emergency response. But how many times do you see divers not performing the checks? Compound that risk by orders of magnitude for rebreather checklists and overhead dive planning.

Many divers operate on a thin margin where a single simple failure can trigger a cascade to a catastrophic event. It's not a calculated risk because there is no assessment of the risk in the first place. The divers have simply adopted unsafe practices due to the lack of a critical failure in their body of experience (normalized unsafe practice). Compare to texting while driving.

Industry combats normalization through peer cross checks, inspections, and rigorous procedural compliance. Which has lead to continuous improvement in worker and plant safety at high hazard facilities. Divers, on the other hand, often have an individualist perspective that leads them to believe that safe practices are entirely optional (my hobby, my life, my rules).

 

[KevinNM]

Jill Heinerth mentions being encouraged to dive with a CCR rig that showed an error, but would still in theory operate. She declined, but noted years later that some of the people who told her it was fine to dive are now dead after CCR mishaps.

 

[Omisson]

Jill Heinerth mentions being encouraged to dive with a CCR rig that showed an error, but would still in theory operate. She declined, but noted years later that some of the people who told her it was fine to dive are now dead after CCR mishaps.

That's the "cut a corner and survive so it's ok" creep into safety that causes deaths- Jill knows better than most the need for diligence and redundancy. She's a greater educator and a pioneer. She walks the walk.

 

[rx7diver]

Yes, this type of thing is insidious, isn't it? Early on I learned the lesson from a dive buddy: We were doing a deeper dive in the Great Lakes. I had a free flow at depth and shut down the offending post, no problem. I motioned to continue the dive. My buddy, a very experienced Great Lakes diver and Florida cave diver, wagged his finger at me and motioned to abort the dive. I was a bit confused. After all, I had one good, functioning reg, and a competent buddy who had two good, functioning regs. What's wrong with continuing?! I received his gentle but sober lecture topside.

Safe Diving,

rx7diver

 

[Wookie]

I can't even begin to tell you how many folks continue their dive with a malfunctioning computer, then can't figure out why we "make such a big deal out of it" on a multiday liveaboard trip. Day 3, they forgot to set their nitrox in the morning, computer errors out on O2 and locks them out for 24 hours.

Me: It's OK, use your dive history to calculate your pressure group, and use a depth gauge and bottom timer to dive for the next 24 hours.
Them: Can you help me?
Me: (After looking at the tables, and knowing the answer beforehand) without the computer, you were off the tables on the first dive.
Them: You mean I have to sit out a day?
Me: Why didn't you just come back up when your alarm went off and reset your computer?
Them: I didn't want to miss a dive.
Me:
Them:

 

[Omisson]

I can't even begin to tell you how many folks continue their dive with a malfunctioning computer, then can't figure out why we "make such a big deal out of it" on a multiday liveaboard trip. Day 3, they forgot to set their nitrox in the morning, computer errors out on O2 and locks them out for 24 hours.

Me: It's OK, use your dive history to calculate your pressure group, and use a depth gauge and bottom timer to dive for the next 24 hours.
Them: Can you help me?
Me: (After looking at the tables, and knowing the answer beforehand) without the computer, you were off the tables on the first dive.
Them: You mean I have to sit out a day?
Me: Why didn't you just come back up when your alarm went off and reset your computer?
Them: I didn't want to miss a dive.
Me:
Them:

Things do not "get better in the morning" for such divers. It's amazing how many people will take risks like this routinely.

 

[ppatin]

I agree with Mullane's thesis: "Normalization of deviance" leads to increased risk. I don't completely agree with his example. Not completely. My understanding is, Challenger's last flight occurred on a day that started off much, much colder than with any previous space shuttle flights'. These very cold temperatures compromised the ability of the booster rocket O-rings to quickly and sufficiently seal the rockets' joints when pressure built up inside the booster rockets, which led to the breaches and the catastrophe. It was the unprecedented, excessively cold temperature that is believed to have been the direct cause of the catastrophe.

If Challenger had flown, instead, again and again at this very cold temperature, with the catastrophe eventually "catching up" with NASA, then Mullane's using the Challenger catastrophe as an example would make more sense (to me).

I'm going from memory hear so I may be misremembering, but I believe that o-ring "blow-by" (hot gasses making it past the primary o-ring) was one of the things that was mishandled. The original standard was that blow-by should never have happened, period. It did start occurring pretty early on in the program but since it didn't lead to a disaster initially the "new normal" became that gasses making it past the primary o-ring were acceptable since the secondary o-ring prevented a disaster from occurring. If the issue of blow-by had been addressed rather than accepted the Challenger disaster could have been prevented. I think that's why he uses it as an example (well that and the fact that Mullane was an astronaut, and he uses that as a selling point for his speaking career.)

 

[rx7diver]

I'm going from memory hear so I may be misremembering, but I believe that o-ring "blow-by" (hot gasses making it past the primary o-ring) was one of the things that was mishandled. The original standard was that blow-by should never have happened, period. It did start occurring pretty early on in the program but since it didn't lead to a disaster initially the "new normal" became that gasses making it past the primary o-ring were acceptable since the secondary o-ring prevented a disaster from occurring. If the issue of blow-by had been addressed rather than accepted the Challenger disaster could have been prevented. I think that's why he uses it as an example (well that and the fact that Mullane was an astronaut, and he uses that as a selling point for his speaking career.)

Also from *distant* memory, these "near misses" (manifested by scars/burns on the O-rings), which increased as temperature decreased, were incorporated in my Bayesian analysis. There is quite a lot of critical information in these near misses—quite compelling even using a non-informative prior.

Yes, I think you're right: Your summary (i.e., the issue of blow-by was never addressed) is probably why Mullane used Challenger to illustrate his point. Thanks.

Safe Diving,

rx7diver