FRAMA: A safety assessment approach based on Functional Resonance Analysis Method

•Extension to Functional Resonance Analysis Method, including a framework with steps.•Formal modeling based on rules of function variability for practicably exhaustive analysis.•Application to a ferry capsizal, obtaining more details about the accident causes. Based on the Functional Resonance Analysis Method (FRAM), a framework associated with practicable steps is presented to support hazard analysis for socio-technical systems. In the FRAM-based analysis (FRAMA), the derivation of rules describing function variability (RFV) is highlighted to understand the influence of system elements on each other, as well as to determine how the various performance of functions can occur and aggregate. The RFV enable the analysis to be conducted by means of model checking (MC), and consequently facilitate exhaustive search, based on the FRAM modeling, for potential performance of the system functional model. How hazards result from highly complex interactions among system functions, and how the scenario(s) where safety constraints are violated, is illustrated. In a case study, the method FRAMA was applied to a typical ferry capsizal accident, and the model checking results illuminate more details about the accident causes than both the details provided in the officially-issued investigation report and those produced by the current FRAM.