Abstract: In order to solve the safety assessment issue of the next generation IMA, safety cases for the IMA were constructed and demonstrated. The deficiency in SAE ARP4761 standard was analyzed, and the basic structure of safety case was described .The applicability of the method for IMA was analyzed. Then the safety cases for IMA were constructed from three aspects, the safety requirements, framework and implementation. Two demonstration methods, process based and product based demonstrations were discussed. Safety demonstrations were implied on the system management function of IMA based on the GSN. The results show that the safety cases can correspond to the development process of civil aircraft systems,and can provide a more effective way to integrate the safety evidence resources in the safety assessment process, thus establishing a clear relationship between the system safety requirements and safety evidences.

Key words: civil aircraft, system safety assessment, integrated modular avionics(IMA), safety case, goal structuring notation(GSN), airworthiness