Analyses of industrial accidents have often concluded that 'human error' is a determining factor in 70-80% of the cases. Furthermore, multiple contributing errors and faults are normally found, because several defenses against accident have been used to protect a hazardous process. Typically, it is also concluded that the 'root cause' of the accident was a human error on part of a person involved directly in the dynamic flow of events, a pilot, a process operator, or a train driver.
Consequently, great effort has been spent to improve safety by better training schemes, by safety campaigns motivating the work force to be safety conscious, and by improved work system design to prevent human errors. In addition, considerable resources have been spent on human error research and comprehensive programs are established to define and categorize human behaviour fragments in terms of errors without any significant success; 'human error' data bases still do not exist.