“a long incubation period [before a final disaster] with early warning signs that were either misinterpreted, ignored or missed completely” – Diane Vaughan

NASA normalized the deviances in performance of the tiles on the Columbia shuttle. They were performing fine for multiple trips, and the degradation during trips was noted but ignored as they never caused a problem, until it lead to a loss of life event.

Feels similar to software system degradation over time, where team members recognize noisy alerts, but become so used to them that they are normalized. Then a huge outage occurs.