roulishollandais,
I think one has to be realistic when citing percentages. The gold standard is Six-Sigma - 99.99966% free of defects. You can calculate what this might mean in terms of successful flight hours. However, I should point out this does not include the thing that nature might throw at you, variables that are beyond any control. When you take into account the machine and all of its various component makeup, the human factor and all that could and does imply, and the nature of flying in an atmosphere that can be and is unpredictable at best, Six-Sigma can be a goal, an admirable goal, but may take considerable time to reach, if at all obtainable. Think of all that must happen to make it so. However, the human aspect can overcome some of the shortcomings of the other two variables, as has been pointed out by various pilots, based on proper training, proper instincts and hands on learned abilities...
TD