The Impact of System Design on Human Error

All human activity takes place within and is influenced by the environment, both physical and social, in which it takes place. It is, therefore, often very difficult to separate system design error from operator error In highly automated systems, the operator is often at the mercy of the system design and operational procedures. One of the major mistakes made by the operators at Three Mile Island was following the procedures provided to them by the utility. The instrumentation design also did not provide the information they needed to act effectively in recovering from the hazardous state [99], 

In the lawsuits following the 1995 B757 Cali accident, American Airlines was held liable for the crash based on the Colombian investigators blaming crew error entirely for the accident. The official accident investigation report cited the following four causes for the loss [2]  

The flightcrew s failure to adequately plan and execute the approach to runway 19 and their inadequate use of automation. 

Failure of the flightcrew to discontinue their approach, despite numerous cues alerting them of the inadvisability of continuing the approach. 

The lack of situational awareness of the flightcrew regarding vertical navigation, proximity to terrain, and the relative location of critical radio aids. 

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