Abstract
Various methods have been used for safety and reliability as it becomes more difficult to ensure safety owing to the increasing complexity and scale of systems. This study aims at making it easier and more efficient to discuss risks and countermeasures for completeness, review, and knowledge transfer by improving methods to create fault tree analyses which focus on the GSN [1], which are among the methods used to describe assurance cases. More specifically, the purpose of this study is to incorporate strategy and context, GSN concepts, along with reason, which is a new concept, into FTA; the study focuses on three points. One point is support for the safety designer to draw a mutually exclusive and collectively exhaustive (MECE) FTA. The second is to make it easier to understand diagrams and meanings of FTA compared with the usual methods. The third is to make creating an FTA more efficient and to pass on existing know-how. Eventually, FTA can achieve completeness, review, and knowledge transfer. An introduction is provided in the first section. Next, the methodology covered in this paper is explained in the second section. The third section describes the proposed notation method based on two proposals made in this paper. In the fourth and fifth sections, results and discussion are provided, respectively. Finally, in the sixth section, conclusions are described.