Introduction : This position paper presents how the engineering of interactive system may be impacted when these systems are designed to be deployed in safety critical contexts. These domains are specific as they are usually driven by constraining standards defining precisely best practices and mandatory processes to be applied. The authors discuss how it is possible to take into account these constraints in real-life domains where critical and non-critical components may coexist. Engineering approaches in this context must jointly exploit formal description techniques (for the critical parts) and standard software production techniques (for the non-critical part). The paper describes how Engineering Interactive Systems in these domains particularly impact design and development processes, systems architectural aspects and developers’ tasks.