It appears that there are enormous differences of opinion as to the probability of a failure with loss of vehicle and of human life. The estimates range from roughly 1 in 100 to 1 in 100,000. The higher figures come from the working engineers, and the very low figures from management.
Richard P. Feynman (2011). “"What Do You Care What Other People Think?": Further Adventures of a Curious Character”, p.238, W. W. Norton & Company
