A model-based safety analysis approach for airborne systems using state traversals

Safety analysis is an important task in both the development and certification of civil aircraft. The traditional safety analysis is significantly dependent on the skills and experiences of analysts. A model-based safety analysis approach is proposed for airborne systems based on the model built with Simulink. This study builds Simulink models of typical failure modes as well as the fault injection methods. The responses of system performances are monitored by traversing all failure combinations based on a state space reduction method. The system will be in an unsafe condition when the responses exceed their thresholds. The minimal cut sets of the system are obtained automatically by recording the failure combinations leading to the unsafe condition. Finally, a lateral-directional flight control system is taken as a practical example to illustrate the application and effectiveness of our proposed method. The result shows that our method has higher accuracy and the causes of the unsafe conditions can be determined by the automatic generation of the minimal cut sets. Additionally, the cumbersome work of building a traditional safety analysis model such as the fault tree, the Markov model, or the dependence diagram can be avoided.