People who work in life critical situations generally take a zero tolerance approach to mistakes. Whether you're landing airplanes, performing surgery, or handling nuclear missiles, it's important to get it right every single time.
Error management is a discipline unto itself, and far too broad a topic to explain here. The interesting part, though, is the balance between rigorous attention to detail and non-punitive management (PDF file) of the people actually doing the work. On the one hand, it's important to have and follow detailed procedures. On the other, if you fire everyone who makes a mistake, people will just hide their mistakes and you won't know where the problems in the organization actually are.
That's at the organizational level. Unfortunately, errors that come to the attention of people outside the organization are likely to become evidence in a lawsuit. (This is especially an issue with medical errors.) There's that punitive culture again. Can doctors learn from their mistakes if they are punished for admitting they made them? (Along these lines, I've mentioned Atul Gawande's excellent book Better: A Surgeon's Notes on Performance before. It's worth a look for a doctor's perspective.)