Understanding the Implications: Critical Path Analysis vs Dependent Failure Analysis in ISO 26262 Safety Methodology

ISO26262 - Parts 4,6,9 - 2nd edition [1–3] was published in December 2018 and addressed functional safety management and engineering at organizations and projects involved in safety activities for road vehicles and motorcycles, to provide them with requirements and work products needed to manage this activity in pre- and post-production phases for vehicles or vehicle systems. In this paper, we provide an insight between two distinct kinds of safety analysis methods tackling both properties, the (Technical) independence property as well as the freedom from interference property, one is standardized by ISO26262 – part 9 [3] which is the dependent failure analysis method (DFA), while the other one is not standardized by the ISO26262 - Parts 4,6,9 [1–3] and IEC 61508 [4] which is the critical path analysis method (CPA). The paper draws from the authors' past experiences in the automotive sector. In addition, the following case study is considered as one of the pilots for investigating the software-dependent failure analysis vs the critical path analysis by highlighting the approaches for each of them.