The safety assessment represents a key aspect to consider during the design and development of a complex system, especially in the aerospace domain. Nowadays the traditional methods (Fault trees, FMEA, HAZOP) used for the qualitative and quantitative analyses reveal several drawbacks, for example the large investment of time needed to perform the safety assessment of a single system architecture. MBSA (Model Based Safety Assessment) is a new method to elaborate the dysfunctional models of complex systems by using block diagrams. In the context of digitalization and constant innovation, MBSA finds interesting applications in several phases of the safety assessment process in order to substitute the traditional methods and tools, in particular the fault trees.