Why Can't We Get a Handle on This Safety Thing 4

Finally, I was left with only one conclusion. What happened to me was nothing more or less than exactly what the potential result was, during any of the times I had landed under similar or more challenging circumstances. It was a dangerous landing because of what could have (and did) happen. The corollary, of course, is that the other landings I had done on more challenging gliders, in more challenging conditions were also dangerous. (In fact, they were more dangerous.) And they were so in spite of the fact that no bad results ensued in any of those landings.
And suddenly I felt like I was beginning to understand something that I hadn't previously understood.
You see, here's how I think it works. The overriding determinant of pilot safety in hang gilding is the quality of pilot decision making. Skill level, experience, quality of equipment--all of those things are not determinants. What those things do is determine one's upper limits. More skill gives you a higher limit, as does more experience or better equipment. But safety is not a function of how high your limits are, but rather of how well you stay within those limits. And that is determined by one thing: the quality of the decisions you make.
How good do those decisions have to be? Simply put, they have to be just about perfect. Consider the types of decisions you have to make when you fly. Do I fly today? Do I start my launch run at this time, in this cycle? Do I have room to turn back at the hill in this thermal? Can I continue to follow this thermal back as the wind increases and still make it back over the ridge? Each time you face such a decision there is a level of uncertainty about how the conditions will unfold. If you make the "go" decision when you're 99% sure you can make it, you'll be wrong on average once every 100 decisions. At 99.9%, you'll still be wrong once every thousand decisions. You probably make 50 important decisions per hour of airtime, so the thousand-decision point comes every 20 hours, or about once or twice a year for the average pilot.
So, to be safe you have to operate at more than 99.9% certainty. But in reality, 99.9% is virtually impossible to distinguish from 100%, so really, for all intents and purposes, you have to be 100% sure to be safe.
And now I think we can begin to understand the problem. Let's first consider this: We all have a strong incentive to make the "go" decision. The "go" decision means I launch now, relieve my impatience to get into the air and avoid the annoyance of the pilots waiting behind me, instead of waiting for the next cycle because the wind is a little cross and the glider doesn't feel quite balanced. It means I turn back in this thermal and climb out above launch and stay up, instead of making the conservative choice and risk sinking below the top and maybe losing it all the way to the LZ. It means I choose to fly today, even though conditions are beyond my previous experience, rather than face listening to the "there I was" stories of my friends in the LZ at the end of the day, knowing that I could have flown but didn't, and knowing that they did and were rewarded with enjoyable soaring flights.
So the incentive is there to choose "go." The only thing we have to counter this incentive is a healthy respect for the possible dangers of failure and our ability to evaluate our prospects for success. And here's where we get caught by a mathematical trap.