Safety Life Cycle

The safety life cycle is the series of phases from initiation and specifications of safety requirements, covering design and development of safety features in a safety-critical system, and ending in decommissioning of that system.

The basic concept in building software safety, i.e. safety features in software, is that safety characteristics and behaviour of the software and system must be specified and designed into the system.

The problem for any systems designer lies in reducing the risk to an acceptable level and of course, the risk tolerated will vary between applications.

When a software application is to be used in a safety-related system, then this must be borne in mind at all stages in the software lifecycle.

The process of safety specification and assurance throughout the development and operational phases is sometimes called the ‘safety life cycle’.

The first stages of the life cycle involve assessing the potential system hazards and estimating the risk they pose. One such method is fault tree analysis.

This is followed by a safety requirements specification which is concerned with identifying safety-critical functions (functional requirements specification) and the safety integrity level for each of these functions. The specification may either describe how the software should behave to minimize the risk or might require that the hazard should never arise.

A ‘normal’ process model is then followed with particular attention paid to the validation (inspection, testing etc.) of the system. Part of that validation should be an explicit safety validation activity.

Famous quotes containing the words safety, life and/or cycle:

    The high sentiments always win in the end, the leaders who offer blood, toil, tears and sweat always get more out of their followers than those who offer safety and a good time. When it comes to the pinch, human beings are heroic.
    George Orwell (1903–1950)

    Wisdom is not just knowing fundamental truths, if these are unconnected with the guidance of life or with a perspective on its meaning. If the deep truths physicists describe about the origin and functioning of the universe have little practical import and do not change our picture of the meaning of the universe and our place within it, then knowing them would not count as wisdom.
    Robert Nozick (b. 1938)

    The Buddha, the Godhead, resides quite as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain or in the petals of a flower.
    Robert M. Pirsig (b. 1928)