Contents I. Introduction
The missile system has the characteristics of complex structure, dangerous substances and energy intensive, so the failure of devices, integrated circuits and software may lead to major accidents such as disintegration, crash and explosions. The safety of a missile is closely related to its own safety and human life. The frequent occurrence of accidents and hidden dangers of missiles have become a constraint in achieving the goal of high reliability and safety. Therefore, the accident based on fault monitoring is an important part of the missile system PHM. System safety analysis and assessmentl'J is a work to get system risk information, research the law of system risk changes and assess the system risk level, so that people can be aware the system safety status, identify the weakness and get the risk uncertainty, assist the risk decision making, guide the risk control, ensure the system to achieve the best safety status, which can provide theory support of safety analysis for the missile system PHM. The traditional missile system safety analysis and assessment methods are difficult to accurately and comprehensively assess the results of the assessment, component failure effect analysis, component failure to the system failure effect analysis modeling methods, the dynamic changes law of the system safety are largely restricted engineering application and further development of security risk analysis and assessment. Therefore, it is necessary to study the effect of component failure on system safety risk according to system characteristics. Goal Oriented (GOy2]is a method developed by Kaman Scientific to analyze the comprehensive safety and reliability of weapons and missile systems, such as SPRINT, SPARTAN, NIKE HERCULES, HONESTJOHN, LANCE, MADM, M454 and M422 etc. Also the Navy weapon systems including POLARIS, POSEIDON and TRIDENT etc. Pl, Later this method is applied on the risk probability of nuclear power station emergency shutdown system, emergency diesel power generation system and auxiliary water supply system[4]–[6]. All of the above facts can prove the strong ability of analysis engineering application. In recent years, with the continuous improvement of the functions and algorithms of GO methodlr!”, it has become an effective and general safety analysis method for its simplicity, ease of use, versatility, comprehensive analysis capability, high efficiency, and low cost. This paper proposes an accident probability determining method for missile system. And taking a certain missile system as example, its accident transfer model and qualitative analysis are conducted using GO method. Compared with the result of dynamic FT A, the advantages and rationality of the GO method are verified.
