Issues in Human Reliability

Abstract

The correct premise of the topic of human reliability is that system personnel fail in their responding just as equipment does, and so they must be considered along with the equipment in the specification of system reliability. The goal of human reliability efforts as they are presently pursued is to find measures of the reliability of human performance that are expressed in the same terms as measures of equipment reliability and can be combined with them to produce system reliability. The thesis of this paper is that conceptualizing human reliability in these terms raises methodological problems that are likely to prevent this goal from being achieved. What is lacking are: a definition of human failure, units of human behavior whose reliability can be determined, a way to synthesize the reliability of larger behavioral sequences from the units if we could specify them, and a way to integrate human reliability, if it could be determined, with equipment reliability. Monte Carlo modeling is seen as a promising approach to the topic.