Hazardous States and Accidents

I have long wanted to write about how root cause analysis is a crap technique for learning from failure. In order to do that, we need to know some fundamentals first. These are good to know for anyone designing anything they want to be reliable.

A hazard is an accident waiting to happen

In safety-critical systems, we distinguish between accidents (actual loss, e.g. lives, equipment, etc.) and hazardous states (sometimes called only “hazards”). If we say that HH stands for hazardous state, EE for environmental conditions, and AA for accident, then the equation is