Where systems are both tightly coupled and interactively complex, serious accidents are a structural property rather than an exception.
Perrow's 1984 analysis of Three Mile Island. The two properties are what matter: tight coupling means no time to intervene, interactive complexity means the failure mode was not anticipated.
In practice
- A chemical plant where a valve fault propagates in ninety seconds through a process nobody fully models is not badly run; it is that kind of plant.
- An automated trading system whose components each behave correctly produces a cascade in four minutes that no operator could have interrupted.
- Subject
- Risk & Reliability
- Essay
- How accidents actually happen