The article presents a new method relying on Model-Based System Engineering concepts in order to efficiently deal with real-time and dependability constraints, throughout the design process of embedded systems. The method is de-scribed and its use is exemplified on the LEA project shared by MBDA and the PRISME Institute. The method is built in a SysML-centric context, and proposes to merge current effi-cient methods for safety, reliability and real time constraints analysis. In particular, the AltaRica Data Flow and AADL languages are integrated in the framework supporting the method.