Error mode prediction

The study of accidents ('human errors') has been dominated by efforts to de velop 'error' taxonomies and 'error' models that enable the retrospective i dentification of likely causes. In the field of Human Reliability Analysis (HRA) there is, however, a significant practical need for methods that can predict the occurrence of erroneous actions - qualitatively and quantitativ ely. The present experiment tested an approach for qualitative performance prediction based on the Cognitive Reliability and Error Analysis Method (CR EAM). Predictions of possible erroneous actions were made for operators usi ng different types of alarm systems. The data were collected as part of a l arge-scale experiment using professional nuclear power plant operators in a full scope simulator. The analysis showed that the predictions were correc t in more than 70% of the cases, and also that the coverage of the predicti ons depended critically on the comprehensiveness of the preceding task anal ysis.