Monday, September 19, 2011

ERROR CHAINS

By Mark Young

“For the want of a nail, the shoe was lost; for the want of a shoe the horse was lost; and for the want of a horse the rider was lost, being overtaken and slain by the enemy, all for the want of care about a horseshoe nail.”
–Benjamin Franklin, Poor Richard’s Almanack
 
The cover story for this edition took me back to an article that ran in the second issue of Dive Training — December 1991. It was a Learning Experience column written by a guy who got into trouble diving from a private boat.The reason that article readily comes to mind is because I never forgot it; I’ve always been amazed that it’s so possible for intelligent people to do dumb things. More about that in a minute, but here’s a recap of the event.

So the author’s friend calls and asks if he would like to go lobster diving. The friend owns a boat, they’re in South Florida and the Gulf Stream should make it an easy drift dive; the divers will tow a float, which the boat will follow to pick them up at the end of the dive.

On this day the boat will be driven (and the float will be followed) by the guy’s new girlfriend. She’s never done this before; in fact he’ll teach her to drive on the way to the dive site. It’s just the three on board so she will also be alone on deck as the sole observer. None of this is too smart so far.

Before leaving the dock they question whether to dive. The seas are running 2 to 4 feet, expected later to become 3 to 5. They decide they can beat that, and go. The wind is picking up when they reach the site so their next good idea is that it’s a good idea to get diving and get back soon. In other words, no time for predive briefings or much of a dive plan or, for that matter, to show her how to use the boat’s radio or find her way back to an inlet if necessary. It’s also getting pretty late in the day. They continue on and make the dive.

You can see what’s coming; why couldn’t they?

We tend to think that accidents come from out of the blue, but most don’t. They are usually at the end of a series of events. In fact far too often accidents or incidents are both foreseeable and avoidable. So why do even smart people do such predictably dumb things?

The best answers come from the archives of the National Transportation Safety Board, the operation that investigates airplane accidents. After thousands of well-documented cases, here is what they’ve determined.

The chain of events leading up to an accident is often called the error chain. At the start of the chain is almost always some human factor of personality, of judgment or fault. It’s the mental mechanism that, for example, keeps the pilot flying into iffy weather eager to make his destination when he probably shouldn’t have left to begin with, or should have fixed his gyro, or taken the time to top off his fuel tanks for margin, or had the opportunity to stop at numerous airports along the way. He instead ends up a statistic.

Those same human factors in play, the author of the story hesitantly yields to the boating experience of his friend, who committed to take his buddy diving and is hesitant to back out while the girlfriend, obvious to all to be incompetent for the task, wants to appear cool, capable and willing. There were also at least six event links along the error chain when any one of the three could have said no, and broken it. The horseman is slain, the pilot is lost and the divers adrift on a dark sea, worried as much about how the girl will get back home as about how they will. Lucky for all of them it ends up OK.

Diving from a private boat is fantastic fun. The how-to-do-it article in this edition is a very good primer. What is left to consider when it comes to both your ultimate safety and enjoyment, is awareness of that chain of events. Those not tuned in to their instincts are rarely aware that an accident is forming, so if divers and boaters pay attention and accept the responsibility for safety, most links will be broken before the chains that cause accidents can even begin. And at that time when your gut does kick in, you only have to break one link in the chain of events to never know what was coming.

In the end, it’s always better to be on shore wishing you were in the water than in the water wishing you were on the shore.

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