ABSTRACT
In Human Reliability Analysis the notion of human error does not correspond only to the likelihood that an operator will not perform correctly the task that he has been assigned to do but also (among other things) to the likelihood that he will not perform the assigned task within the required time. Most of the critical tasks include the concept of time in their characterization as ‘‘critical’’ and most of the error taxonomies developed specifically for human reliability analysis include errors like ‘‘too early/too late’’, ‘‘action performed at wrong time’’, ‘‘delayed action’’, ‘‘operation incorrectly timed’’, ‘‘too slow to achieve goal’’ and ‘‘inappropriate timing’’ (Embrey 1992, Hollnagel 1998, Isaac et al. 2002, Kontogiannis 1997, Swain & Guttmann 1983). What is thus important for Human Reliability Analysis is the identification and quantification of human error and at the same time the estimation for the response time of the operator in the performance of a critical task. In modeling human performance for Probabilistic Risk Assessment it is necessary to consider those factors that have the biggest effect on performance. The same is also valid for factors that influence operators’ response time.
