Critical Stages and Sources of Error

The critical stages and sources of error summarised above are dealt with in greater detail in the following sections. 

Management policies are the source of many of the preconditions that give rise to systems failures. For example, if no explicit policy exists or if resources are not made available for safety critical areas such as procedures design, the effective presentation of process information, or for ensuring that effective communication systems exist, then human error leading to an accident is, at some stage, inevitable. Such policy failures can be regarded as another form of latent human error, and will be discussed in more detail in Section 2.7. 

The derivation of these requirements is a critical step in the development process because errors and deficiencies at this stage will eventually challenge the validation process if not detected during development. Additionally, defects in the computer system requirements are a potential source of common cause failures in redundant subsystems containing identical software. 

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