Accident Analysis

[GDI]

Just a reading for your pleasure, quality comments welcomed:

ACCIDENT ANALYSIS


HOW WE USE THE LESSONS LEARNED

No other form or discipline of diving in the non-military or commercial diving world reviews and criticizes itself the way that recreational technical divers do. Cave divers are considered the most technical of this group and it holds true that they are onto themselves the most critical of all aspects of their chosen form of diving discipline. The process from which they guide their exploration so that those who will come after shall do so with lessened risk is referred to as Accident Analysis.

If I was to define Accident Analysis as applicable to the cave diving community I would have to say that it is the lessons learned following a detailed examination of the elements leading up to an event that is without apparent cause, that is unexpected or unintentional in nature often resulting in an unfortunate outcome.

Statistics have shown that since 1960 over 400 divers have perished in underwater caves throughout North America. Not all these divers were cave divers by certification; some were open water scuba instructors. This illustrates that the cave environment holds no bias to who may ever cross into this overhead darkened world. The training we do today to assure the safety and enjoyment of cave diving is due in part to our own self critique and observation of guidelines established through Accident Analysis. After all it really takes very little skill to enter the cave; our training is designed to exit the cave.

A single accident can be felt throughout the entire cave diving community. A study of these accidents has had an overwhelming effect upon the training and development of this sport. By compiling a list of safety procedures and studying those which were violated resulting in a cave diving fatality, a pioneering cave diver named Sheck Exley discovered that there was a commonality that contributed to the fatality of some early cave divers. Sheck Exley founded the basis of what is considered the building blocks of any cave diving educational system. Time has proven that this approach is an effective tool to preventing further fatalities in the overhead environments. Analysis of accident documentation has demonstrated five (5) contributing factors to diver fatalities and we list them here in their frequency of occurrence and thus making the rules of safe cavern and cave diving.

A. Training – Lack of training for the specifics of the cavern and cave diving environment. This is a major contributing factor;
B. Continuous Guideline – Failure to run a continuous guideline to the open water allowing for a direct ascent. This is by far the most common cause of cavern and cave diving fatalities. Many divers site exception to the rule and become complacent in running a continuous guideline. There are NO EXCEPTIONS TO THIS RULE;
C. Air Rule of Thirds – Failure to reserve at least two thirds (2/3) of the starting air supply for the exit and ascent to the surface, also known as the 1/3 Rule or the Rule of Thirds. This is the second most common cause of cavern and cave diving fatalities. This rule is adjusted to the equipment configuration, dive certification level and specific cavern or cave system conditions;
D. Depth – Exceeding the maximum depth limits for a level of training and as determined by the breathing medium used such as enriched air. This is the third most common direct cause of cave diving fatalities. Cavern dives are limited to a maximum depth of one hundred (100) feet. No recreational cave dive is to be deeper than one hundred thirty (130) feet. Responsible divers must always be aware of any depth related risks; and
E. Three Lights - Failure to have three (3) lights per diver is considered a major contributory factor. Such is this rule that some dive sites have restrictions of access against non-certified cavern or cave divers from carrying lights. It has proven one of the most effective ways in preventing unnecessary emergencies.

Unescorted and untrained open water divers can dive relatively safe if they avoid entering the cavern or cave, remaining in the direct ascent zone and they do not carry lights. Many divers enjoy the sport of diving and it is the responsibility of the cavern and cave diver to be alert and advise the untrained diver of the risks associated with the cavern and cave diving environment. As you would select a cave diving team based on their training, certification, equipment and attitude so must you be responsible to the untrained diver demonstrating a positive impact by a member of the cave diving community.

 

[cornfed]

I guess the next question is are there a similar set of rules that would apply to recreational/NDL diving?

 

[Rick Murchison]

I guess the next question is are there a similar set of rules that would apply to recreational/NDL diving?

To my knowledge we've never applied the same bounded scrutiny to recreational diving accidents, and that is in large part the purpose of this forum.
However, I would cite five recurring themes, lessons that are along the same lines as those gleaned from the caving world, and they are:
(1) lack of training for the environment
(2) lack or improper use of equipment
(3) inadequate/impropper gas planning/management
(4) diver fitness
(5) depth
Rick

 

[Ayisha]

Not allowing untrained divers to carry lights at certain sites is simple, yet brilliant. What an easy way to keep them (us... or me) out of caves! No false comfort by being able to see...

 

[GDI]

I find that for most concerns there is a balance, a block of

The Diver, Their equipment, their training, the environment

If one is not up to par or prepared there can be a problem

 

[cornfed]

I find that for most concerns there is a balance, a block of

The Diver, Their equipment, their training, the environment

If one is not up to par or prepared there can be a problem

At the risk of over simplifying things, I think this can be boiled down to training. Without adequate training someone might not realize the equipment is inappropriate, or that they're entering and environment that shouldn't be in.

 

[GDI]

Cornfed, I hear ya!
Taking into account That a unknowing student diver enters a LDS and requests scuba lessons. The instruction would need to cover the aspects of skills, limitations, environments. Most instructors I would like to think covers these things but there is still a disconnect somewhere that causes people to go beyong what they know. Curiosity, ego, peer pressure. Sometimes the instructors are the worst violators and students follow by example. Training is the first point though isn't it

 

[cornfed]

Taking into account That a unknowing student diver enters a LDS and requests scuba lessons. The instruction would need to cover the aspects of skills, limitations, environments. Most instructors I would like to think covers these things but there is still a disconnect somewhere that causes people to go beyong what they know.

My OW instructor was very good. I know, I know... your basic OW instructor is like your real estate agent; everyone thinks their's was great. However he put a large amount of emphasis on progressing slowing and gaining experience. He often talked about how not only is there often more life in the shallow portions of the reef but you get more time to see it. Sure anyone can read the tables and figure this out themselves but hearing this multiple times helps drive the point home. He also covered basic air consumption. Which he coupled with navy deco tables. We didn't really cover deco in class but in the right hands deco tables have a tremendous pedagogical value. Instead of "your tank will last N minutes at X depth" he took it a step further. We had many examples that went something like this,

"So you're at X ft and you're only planning to stay their N minutes so you don't exceed you NDL. But you see something really cool and before you know it you're past your NDL. The Navy deco tables say you have to stop at M feet for T minutes. How much air will you need? 85 ft3? Hmm.. that's more then you can fit in a tank. Looks like you drown or you'd better hope the is a chamber nearby."

At the end of the last class he gave us a short talk about what we could do now that where certified. He drove home all the points again. There is more to see shallow, the deeper you go the less time you have and the less room for error you have, etc. But expanded them to include things like, "if you go on a wreck dive say on the outside." Seems obvious, but someone needs to say it! Someone asked him what they could do for more experience. He gave the same everyone else does, "I'm teaching AOW soon". But he didn't stop there. He went on to say, "If you bring a buddy and don't get in the way you can use the equipment and pool for free."

Now let's compare this with the class my buddy and his girlfriend took. The only mention of deco was that it was bad and should be avoided. And the best way to avoid it was to get a computer. (My instructor mentioned computers but he said they were expensive and at this stage in our diving we'd be better off spending or money on other gear or better yet renting some gear and going diving!) They never covered SAC rates or air consumption. They never covered this in their AOW class either. By the way, they took the AOW class to get more experience because they didn't feel comfortable after class and had a trip coming up. After the AOW class I caught her telling someone, "we just finished our advanced class so now we can dive below 100 ft!"

After talking with a lot of people I believe my experience wasn't normal but that my friends training was. So I'm not surprised when I hear about people doing stupid things. The don't know they're being stupid because no one every explained the "rules". I take the back, the rules probably were explained... but no one took the time to drive them home.

 

[GDI]

I agree that training is very much the key starter point. Accident Analysis can be used to reinforce that training. Of course this is only if the trainer is willing to learn it and put it forth. The other side is if the points were driven home and the trainee walked away with a understanding of it. I took my first class back in 1976. We actually went through deco diving procedures using US Navy tables. After my what was the equal to O?W class dives back then, we had other dives we did that were deeper and required more planning. Now keep in mind that I was a 16 year old kid, but my instructors drilled home the risks of diving. General dangers and Wreck, Ice, deep were all discussed as far as risks involved. If I knew then what I know now? They made me redo my basic exam over because a wrong answer to any question was not acceptable. Paul Dumas my instructor use to say wrong answers kill people. Many instructors today do not themselves understand the principles fully that they are trying to put accross to their students and I don't care what agency they teach with, it is a systemic problem. This is a sad situation because the more you know the more fun you have.