Wald's unique insight was that the holes from flak and bullets on the bombers that did return represented the areas where they were able to take damage. The dat

Wald's unique insight was that the holes from flak and bullets on the bombers that did return represented the areas where they were able to take damage. The data showed that there were similar patches on each returning bomber where there was no damage from enemy fire, leading Wald to conclude that these patches were the weak spots that led to the loss of a plane if hit, and that must be reinforced. http://en.wikipedia.org/wiki/Abraham_Wald http://en.wikipedia.org/wiki/Abraham_Wald