Abstract
A considerable number of accidents have occurred in the gray zone between the safety domain and danger domain. Two cases can be considered as mechanism to produce the gray zone. In one case, it is difficult for system users to judge whether the system is safe or dangerous. In the design of such systems, designers are required to selectively use designs based on safety assurance or risk avoidance. The other case results from a difference in the thresholds of the perceived risk level for two entities. For example, mutual understanding is required between persons deciding regulations or rules and persons following them. Since it is difficult to completely eliminate the gray zone, this paper focuses on learning in the gray zone for the enhancemant of safety to construct a system safety science.
