A systematic approach for safety evidence collection in the safety-critical domain

In order to show that the required safety objectives are met, it is necessary to collect safety evidence in the form of consistent and complete data. However, manual safety evidence collection is usually tedious and time-consuming, due to a large number of artifacts and implicit relations between them. The potential ambiguities in the textual description of safety objectives even increase the difficulties of collecting the necessary safety evidence. Consequently, suppliers, who have to ensure that the required objectives have been fulfilled, need to investigate safety evidence requirements very carefully and rigorously to avoid collecting any ineffective information, or missing any important information. This paper proposes a systematic, model-based approach to facilitate manual safety evidence collection with clear evidence requirements. To evaluate the effectiveness of our approach, an industrial case study on an avionics Real-Time Operating System (RTOS) is conducted. A large number of evidence items are collected from thousands of artifacts (involving more than 10,000 test cases and nearly thousand pages of requirement specification), for demonstrating the compliance of system development with the avionic safety standard RTCA DO-178C.