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

We observed that safety arguments are prone to stay too abstract, e.g.solutions refer to large packages, argument strategies to complex reasoningsteps, contexts and assumptions lack traceability. These issues can reduce theconfidence we require 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., both used for confidence evaluation.We present an argument pattern integrating three HA techniques, i.e., FTA,FMEA, and STPA, as well as the reactions on the results of these analyses,i.e., safety requirements and design increments. We provide an example of howour pattern can help in argument construction and discuss steps towards usingour pattern in formal analysis and computer-assisted construction of safetycases.