A Safety Analysis Method of Airborne Software Based on ARP4761

Abstract

Most of the functions of civil aircraft are achieved through software at present. Therefore, the safety of airborne software has become an important part of safety analysis. However, to achieve complex functions, the onboard software becomes very complicated, and it is usually difficult to guarantee safety. ARP4761(Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment) is an important safety assessment guideline for civil aircraft, but it believes that software development can satisfy safety as long as the software development process complies with the software development standards, instead of incorporating the software into the safety analysis process. To improve airborne software safety, this paper proposes a safety analysis method based on the ARP4761 process which is tailored to adapt to the software. In the software requirements and design, the method uses FHA(Functional Hazard Assessment) to analyze the hazards of the software and define the hazard levels, then use FTA(Fault Tree Analysis) to build a software fault tree, and carry out CCA(Common Cause Analysis) analysis based on the fault tree; after the software development is completed, the method uses FMEA(Failure Modes and Effects Analysis) and FMES(Failure Modes and Effects Summary) to summarize the failures of the software and return these failures to the fault tree to determine whether the software can meet the defined requirements. At the end of the article, an anti-icing software is used as an example to explain the process and effectiveness of the method.