Realisation and Development


In the same way that reliability, availability and maintainability (RAM) and safety share a large number of techniques and aims, good engineering and good safety engineering have a lot in common, such as the principles of inherent safety. A well-developed safety case will take advantage of the risk reduction provided by these.

Many safety standards make requirements on processes used in developing and implementing a system, most making use of Safety Integrity Levels (SIL) in the determination of the processes to be followed.

Risk reduction or fulfilment of the engineering requirements include use of approaches such as inherent safety, reliability, availability and maintainability (RAM), layers of protection, fault tolerance, and verification and validation (V and V).

Different standards have differing opinions on what is required; for example, guidelines covering hardware and software can be found respectively in Parts 2 and 3 of AS 61508 "Functional safety of electrical/electronic/programmable electronic safety-related systems", or respectively in Def Stan 00-54 Requirements for Safety Related Electronic Hardware in Defence Equipment and Def Stan 00-55 Requirements for Safety Related Software in Defence Equipment.

Why?

The Ariane 5 launch failure may have been prevented by better software engineering.