Creating safety assurance cases for rebreather systems

The creation of safety assurance cases is a new requirement for rebreather manufacturers, where a rebreather is simply understood as a self-contained underwater breathing apparatus. The two main potential benefits to creating safety assurance cases for rebreather systems are: ensuring that the system is sufficiently safe in a given context and showing compliance to a regulatory framework. This paper presents our experience in the process of developing a safety assurance case for a rebreather sub-system, thus providing guidance on this process to other rebreather manufacturers. We used the Goal Structuring Notation (GSN) to develop a safety argument that compelled us to re-evaluate our safety goals, and that provided a basis for productive discussion between embedded systems engineers, systems safety consultants, and reviewers.