Evolving a safe system design iteratively

Abstract

ARP4754 suggests that, whenever possible, aeronautical safety critical systems may be developed as well as checked in an incremental way. But in practice the safe design emerges from the functional essential design in a discontinuous fashion. Engineers take several decisions in the direction of safety that sometimes can loose some of the desired functional characteristics. This can increase the development cost by only detecting functional problems in late phases of the development life cycle. In this paper we propose a strategy that starts from an initial proposed design, where functional behavior is investigated using model checking, and evolves to a reliable and safe design in a stepwise fashion. At each step, where safety aspects are introduced, safety constraints are checked using probabilistic model checking (Markov analysis). The final design emerges when we cannot find any safety violation. © 2010 Springer-Verlag Berlin Heidelberg.