(probability * cost) 979,750
Risk Management
37
3.3 Hazard Analyses and Testing
Hazard analyses were once used mostly by the ???safety??? industry as one part of preparing a ???safety case???
in order to have a system accepted and used. Any system which can cause or fail to prevent death, or
injury must have a ???safety case??? prepared in most countries whose governments are concerned for the
well-being of their people.
Today hazard analyses are also recognized as invaluable means of identifying financial, or indeed any
kind of critical loss. The process is briefly shown in Figure 3.3. Alternatively put, the process is like this:
??? Identify all the hazards (and write a hazard list).
1
??? Model the hazards using an FTA to identify what might ??” if it fails ??” provoke the hazard (based
on the fact that we have only the haziest notion of what the system will resemble).
??? Put the hazard list and the constraints we want to put on all the undesigned bits of an unbuilt
system into the requirements specification.
??? Design a system against the requirements specification. (Review the system to ensure it meets all
these constraints.)
??? Undertake an FMECA to see what would happen if some combination of components fails and
the probability of this happening.
??? Test the components of the system and the system as a whole to see if we can get some evidence
that neither the failure of any individual component nor some (rather small) group thereof will
cause a failure, with sufficient probability to satisfy the people who approve the safety case.
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