> The Challenger disaster could perfectly well have been avoided if they had been willing to look.

The tragedy of Challenger is that Morton Thiokol engineers did look enough to know that the O-ring design was likely to fail under cold weather conditions. This was already a known issue and the engineers specifically recommended that Challenger postpone launch because of the temperature at the pad the night before the launch.

They got overruled... almost certainly for what amounts to political reasons as the big bosses didn't want to throw off the timing of the media-hyped "first class taught from space".