The complexity of these systems makes it impossible for them to run without multiple flaws being present.
The system continues to function because it contains so many redundancies and because people can make it function, despite the presence of many flaws.
The potential for catastrophic outcome is a hallmark of complex systems. It is impossible to eliminate the potential for such catastrophic failure;
Because overt failure requires multiple faults, there is no isolated ‘cause’ of an accident.
When new technologies are used to eliminate well understood system failures or to gain high precision performance they often introduce new pathways to large scale, catastrophic failures. Not uncommonly, these new, rare catastrophes have even greater impact than those eliminated by the new technology.