Safety cntical systos are systeme in which failures may affect the environment of the esem ard cwse injury or desth to the people in that environment. The principal conce of snttry specificetion is to identily requirements that will minimize the probability that su eetem fhiures will occur. Safely requirements are primarily protection requirements and are es oorcened with nomel system operation. They may specify that the system should be shu deym so that wafely is maintained. in deriving safety requirements, you, therefore, need to fin at acceptable balance between safety and functionality and avoid overprotection. There is auint in bankiing a very safe system if it does not operate in a cost-effective way.
Safety specification is usually focused on the hazards that may arise in a given situation, and the events that can lead to these hazards. The activities in the general risk-based specification process, mapped onto the safety specification process as follows:
1.(71).In safery specification, this is the hazard identification process that identifies hazards that may threaten the system.
2(72).This is a process of hazard assessment to decide which hazards are the most dangerous and or the most likely to occur. These should be prioritized when deriving safety regurements.
3.(73).This process is concerned with discovering the events that can lead to the accurrence of a hazard. In safety specification, the process is known as hazard analysis.
4.(74).This process is based on the outcome of(75)and leads to identification of safety requirements. These may be concerned with ensuring that a hazard does not arise or iead to an accident or that if an accident does occur,the associated damage is minimized.
