en.wikipedia.org/wiki/Survivorship_bias

Basically the story goes that planes would fly to the battle field and come back with bullet holes. Experts started charting where the bullet holes (as you can see in the top image) and decided to reinforce the armor in those areas since they were “the most commonly struck by bullets”. Makes sense!!! Exceptttttt… those were the planes that survived, meaning that the bullet we see in the image do not explain why planes fall in battle. Places that have no bullet holes in the image are the areas that, when struck by a bullet, would cause the plane to fall. When they started reinforcing the areas that have no bullets in the image, “plane survival” increased significantly.

I hope my explanation is understandable!