Arguing from Hazard Analysis in Safety Cases: A Modular Argument Pattern

We observed that safety arguments are prone tostay too abstract, e.g. solutions refer to large packages, argumentstrategies to complex reasoning steps, contexts and assumptionslack traceability. These issues can reduce the confidence werequire of such arguments. In this paper, we investigate theconstruction of confident arguments from (i) hazard analysis(HA) results and (ii) the design of safety measures, i.e., bothused for confidence evaluation. We present an argument patternintegrating three HA techniques, i.e., FTA, FMEA, and STPA, aswell as the reactions on the results of these analyses, i.e., safetyrequirements and design increments. We provide an example ofhow our pattern can help in argument construction and discusssteps towards using our pattern in formal analysis and computer-assisted construction of safety cases.