Before debating skills vs. equipment, please consider Risk Compensation

[redacted]

In general the risk may be overstated but divers using rental gear are at the mercy of whoever maintains it which is an unknown I don't have.
Any combination of the above helps.

Many divers have such a poor understanding of scuba gear that they are simply unable to do reasonable risk assessments of gear failures. Divers who rent rather than own probably have even less knowledge about gear. Understanding failure modes and associated risks should be the foundation for recognizing failures, and planning and practicing responses.

 

[Rick Inman]

This was an interesting thread to read. It side-car's a book I am about to finish called Deep Survival, and I recommend it to all divers.

Something I've both experienced and witnessed is what I call increasing risk through experience. Say Fred dives some new deep dark location. It's Fred's first time there so he doesn't know what to expect. He's on guard, on high alert. He's hyper careful with his pre-equipment checks, gas management, awareness in the water...

But after 50 dives at this site, he's gotten used to diving it. It's never given him any trouble, so he does the dive under the assumption that it never will, and he is less careful. But is there any less risk to the dive? It's still 100' in dark cold water. Unless there is some change in skill level, a dive is no less risky just because you've made it before. Yet many divers seem to feel that they are better divers simply because they get accustom to diving and "feel" more comfortable. So they will increase the difficulty of the dive based on becoming accustom to diving rather than increased training.

An emergency on a dive will not be dealt with any better because the diver has made lots of dives at the location. And yet, with experience, rather than training, divers ramp up the risk.

It's promoted on dive boats. Before the 110' swim through, the DM asks, "How many dives do you have to 100' or more?" The vacation diver replies, "Seven." The DM approves and off they go. As if the seven dives somehow proves that this diver has the training and skills to safely make the 110' dive. The diver may feel more comfortable, but that doesn't mean he/she has the skills. Somehow the DM believes that because the diver survived the other seven dives, they are qualified for this one. The odds of an accident happening do not decrease because of how a diver "feels", it decrease based on training and skills. In fact, sometimes new divers (meaning, new to the level of the dive, be it OW, deep trimix, whatever) are the most cautious of all.

The ratio is difficulty to training and skills, not difficulty to number of dives.

And that is my hope for my own diving. Keep me new. Make the safety of each dive as important as every other - whether it be a 30' vacation dive or a 300' deep wreck penetration. Let me always make my risk decisions based on my training and skill, not because I've done it before and survived.

Oh, unless I've got a spare air with me.

 

[ReefHound]

Reg raises an important point discussing a critical aspect of the human element. His example of ABS brakes is only one of many documented examples where the addition of a new safety factor changed human behavior.

I have my doubts about the ABS results. I don't know anyone who drives faster because they have ABS. For the faster drivers, stopping is not on their minds so much as controlling the vehicle (or getting a ticket). Performance tires and suspension make some believe they are a Grand Prix driver. But I think the ABS was due to ignorance, as most people had been taught to "pump the brakes" to avoid wheel lock, which is counter productive with ABS.

 

[ReefHound]

Drew, Risk Compensation is an observation about the statistical behaviour of large numbers of people. It cannot be used to explain the behaviour of an individual: each person has their own reasons for choosing equipment or dive profiles or buddies. However, I suggest that in the aggregate, Risk Compensation has something to say to us about the results in the aggregate.

FYI, the automobile studies are carefully balanced to factor out things like increased numbers of cars on the road.

But at least some studies are not balanced to factor out differences in mileage.
***
Insurance study overlooks mileage?
HLDI does not take mileage into account when claim frequencies are compared among the 1992 year models with standard ABS and the 1991 models without ABS. Though annual mileage tends to decrease with vehicle age, the HLDI unit of exposure (insured vehicle years) makes no difference between the younger ABS and older non-ABS cars.
Antilock (ABS) brakes and their safety. VETA driver support.

 

[ReefHound]

Actually, it does. You may not perceive that to be the case, but when people's driving habits have been subjected to objective measurement, with the same driver driving cars equipped with ABS and those without, it's been shown that's exactly what happens, even though the test subjects, when confronted with the data, denied it just as firmly as you are.

Have you actually read these studies (and have a link) or are you repeating what you've heard?

 

[ReefHound]

I find it interesting that risk compensation seem to be based on the idea that people increase their risks because of added safety features. I think this is different from those who add safety features because they plan to increase their risks.

I also find it interesting that the presumption has been that people first acquire the added training and/or safety features then engage in riskier behaviour. As wrong as it may be, I know a lot of people who have done the reverse by increasing their risks then deciding it might be a good idea to get more training/gear to deal with them. I'm not talking about yahoos going cave diving with no training, but most people I know who have pony bottles began solo diving and deep diving before they got the pony. Then somewhere along the way, having gained knowledge and experience, they begin thinking "what the heck am I doing?" and start worrying that the numbers will eventually catch up with them.

 

[redacted]

I have my doubts about the ABS results. I don't know anyone who drives faster because they have ABS. For the faster drivers, stopping is not on their minds so much as controlling the vehicle (or getting a ticket). Performance tires and suspension make some believe they are a Grand Prix driver. But I think the ABS was due to ignorance, as most people had been taught to "pump the brakes" to avoid wheel lock, which is counter productive with ABS.

I found that surprising also. Perhaps there was something about the experimental protocol that might have contributed to such results. Perhaps the participants were given classes on the "benefits" of ABS and that specific training may have biased the results. I suspect that most drivers don't even know if their car has ABS nevermind understand what it does and does not do.

 

[mikemill]

Just one of the studies:

Driver Response to Antilock Brakes: A Demonstration of Behavioural Adaptation; B.A. Grant and A. Smiley Proc. CMRSC-VIII; pp. 211-220; Saskatoon, Saskatchewan; June 14-16, 1993

Abstract: Drivers adapt their driving behaviour to take advantage of safety features installed in vehicles; the process by which this occurs has been called behavioural adaptation. These behavioural changes often reduce the effectiveness of safety features and their potential impact on overall safety must be evaluated if we are to be able to predict safety benefits. Antilock brake systems (ABS) are an example of a safety feature which has the potential to produce negative behavioural adaptations. The driving behaviour of 81 test subjects, who were exposed to both ABS or nonABS braking and who practiced normal or hard braking (emergency-like), was evaluated to determine how drivers might modify their driving behaviour. The results indicated that those who were shown the increased control available with ABS drove faster in a curve following task, accelerated faster, and used higher brake pedal forces than others who had not been shown the benefits of ABS. It is concluded that drivers adapt to ABS by driving less safely and therefore the overall safety benefit derived from these systems may be less than expected.

 

[don Francisco]

Those who doubt the ABS risk compensation data might be assuming that since ABS only affects stopping, it's very different from things like improved tires and suspensions which improve the "feel" of a car and make drivers feel as safe at higher speeds.

In looking at how improved braking might lead to higher speed, consider the effects of near misses or close calls. Your driving on a rainy or snowy night, the car infront of you stops and you slam on the brakes. If you experience an uncontrolled slide and brace for impact, or your car skids or spins slightly, you'll tend to be more cautious until the memory of the experience fades and you resume your normal habits.

By changing the nature of these close calls, and replacing them with controlled braking, ABS lowers the frequency of these incidents and removes some of the "whew, that was close" factor that makes drivers more careful (at least for a while).

 

[Puffer Fish]

Don, excellent overview. As ABS brakes change how the vehicle will stop...humans quickly adjust.

Boeing learned that lesson with their voice safety systems, which were eventually determined to actually cause crashes, until their design was changed.

The pony bottle, in diving, is potentially another great example. Around half the people I know that carry them, have actually used them for something other than an absolute emergency..I mean what is the reason for carrying it, if you cannot get a couple extra minutes of bottom time every now and again???

Those who doubt the ABS risk compensation data might be assuming that since ABS only affects stopping, it's very different from things like improved tires and suspensions which improve the "feel" of a car and make drivers feel as safe at higher speeds.

In looking at how improved braking might lead to higher speed, consider the effects of near misses or close calls. Your driving on a rainy or snowy night, the car infront of you stops and you slam on the brakes. If you experience an uncontrolled slide and brace for impact, or your car skids or spins slightly, you'll tend to be more cautious until the memory of the experience fades and you resume your normal habits.

By changing the nature of these close calls, and replacing them with controlled braking, ABS lowers the frequency of these incidents and removes some of the "whew, that was close" factor that makes drivers more careful (at least for a while).