To say that accidents are due to human failure is not so much untrue as unhelpful for three reasons:
- Every accident is due to human error: someone, usually a manager, has to decide what to do; someone, usually a designer, has to decide how to do it; someone, usually an operator, has to do it. All of them can make errors but the operator is at the end of the chain and often gets all the blame. We should consider the people who have opportunities to prevent accidents by changing objectives and methods as well as those who actually carry out operations
- Saying an accident is due to human failure is about as helpful as saying that a fall is due to gravity. It is true, but it does not lead to constructive action. Instead, it merely tempts us to tell someone to be more careful. But no one is deliberately careless; telling people to take more care will not prevent an accident from happening again. We should look for changes in design or methods of working that can prevent the accident from happening again.
- The phrase “human error” lumps together different sorts of failures that require different actions to prevent them from happening again.
Source: An engineer’s view of human error, Third edition, Trevor Kletz, 2001
