In a former life I worked for an Air Traffic Control service provider, producing training software for Air Traffic Controllers. Like rock climbing, ATC’s have a lot riding on the line, namely other people’s lives. So they take safety and risk avoidance very, very seriously and put alot of time into studying and perfecting accident avoidance systems.
It was here that I was introduced to the Swiss Cheese Model of accident causation. The concept is that between any potential hazard and accident there is a series of steps or layers. Each of these layers has a series of systemic flaws or holes that, given the right circumstances, allow access through to the next layer (Swiss Cheese). If a number of these, sometimes seemly unrelated, holes line up you end with a catastrophic accident.
