Any complex organization is confronted to hazardous or unpredictable events which are impossible to imagine and to anticipate due to the interactions and the nature of the components of the organization (person, machine, processes, etc.). Some risky situation may then impact the performance, the integrity and the stability of the organization. Actor involved into or in charge of this organization must then be able to detect and to characterize these events, the emerging situations and the possible induced risks. This paper presents a work on progress about a composite approach allowing to model a complex organization and to analyze its behavior when facing new situations. This approach is applied to Health Care Organizations.