System accident

A system accident, or normal accident, is an "unanticipated interaction of multiple failures" in a complex system. This complexity can either be technological or organizational, and often has elements of both. A system accident can be very easy to see in hindsight, but very difficult to see in foresight. Ahead of time, there are simply too many possible action pathways.

These accidents often resemble Rube Goldberg devices in the way that small errors of judgment, flaws in technology, and insignificant damages combine to form an emergent disaster. System accidents were described in 1984 by Charles Perrow, who termed them "normal accidents", as having such characteristics as interactive complexity, tight coupling, cascading failures, and opaqueness. James T. Reason extended this approach with human reliability and the Swiss cheese model, now widely accepted in aviation safety and healthcare.

Once an enterprise passes a certain point in size, with many employees, specialization, backup systems, double-checking, detailed manuals, and formal communication, employees can all too easily recourse to protocol, habit, and "being right." Rather like attempting to watch a complicated movie in a language one is unfamiliar with, the narrative thread of what is going on can be lost. And other phenomena such as groupthink can be occurring at the same time. Real-world accidents almost always have multiple causes. In particular, it is a mark of a dysfunctional organization to simply blame the last person who touched something.

In 2012 Charles Perrow wrote, "A normal accident is where everyone tries very hard to play safe, but unexpected interaction of two or more failures (because of interactive complexity), causes a cascade of failures (because of tight coupling)."

There is an aspect of an animal devouring its own tail, in that more formality and effort to get it exactly right can make the situation worse. For example, the more organizational rigmarole involved in adjusting to changing conditions, the more employees will delay in reporting the changing conditions. The more emphasis on formality, the less likely employees and managers will engage in real communication. New rules can actually make the situation worse, both by adding another layer of complexity and by reminding employees, yet again, that they are not to think but just follow the rules.

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