Probability goal-based approach

Bear in mind that the goal-based safety criteria used to satisfy JAR25.1309 and JSP553 para 1.38 is not directly compatible with the risk-based approach required by the safety case. In this case, the former should rather be used to identify contributing factors within a sequence of events which may lead to an accident. The goal-based approach is thus a useful source of failure/event inputs, along with their probability of occurrence. 

Loss/malfunction of a missile approach warning system (MAWS) may not affect the airworthiness of the aircraft, and could be classified as a minor failure condition (using the goal-based approach) and may be probable in occurrence. However, in accordance with DEE STAN 00-56, this loss could cause loss of the platform as no warning would result in no evasive or protective action, and should thus be classified as a catastrophic failure condition, which should be extremely improbable in occurrence. 

In Chapter 1, we consider the legal issues associated with system safety. The purpose of this chapter is to reinforce the liabilities assumed in the generation of safety related documentation. In Chapter 2 we attempt to put the term safety into perspective, and the basic approaches used to achieve it. The next three chapters will then explore three of these approaches the use of Regulatory Standards is explored in Chapter 3 Chapter 4 considers the risk-based approach, which is widely adopted in the military industry as well as by Health Safety specialists Chapter 5 introduces the civil aeronautical approach to safety assessments, which (for the want of a better term) we shall call the goal-based approach (in contrast to the risk-based approach in Chapter 4) as it provides clear goals (i.e. failure probability targets) for system designers to achieve. 

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