David Mosey (Mosey, 2006) has examined several cases from the short history of nuclear energy. In the second edition this author cites four inter­related types of management error under four general headings:

1. Misperception of hazard. Lack of accurate and consistent understanding of the specific demands/vulnerabilities of the technology.

2. Dominating production imperative. Production considerations override safety. Safety is under-resourced.

3. Unassigned/undefined safety responsibility/authority. Failure to assign, define or assume safety responsibility and/or authority completely or clearly.

4. Failure to recognize, acknowledge or respond effectively to an unsatis­factory or deteriorating safety situation. ‘Denial’ or ‘unawareness’, or the failure to learn from experience, is included here.

Error number 4 includes, of course, the category of ‘normalization of devia­tion’ discussed earlier.

David Mosey clearly illustrates the importance of safety culture to the successful long-term operation of complex technologies. Quite obviously, senior management has a powerful influence on the performance of the whole organization within their authority. Less obvious, and often a neglected factor, is the influence that should be exerted ‘from the bottom up’. To say this in another way, the knowledge flow from junior to senior ranks must be fostered and encouraged. Senior management must be knowledgeable of the details of the organization they manage. This require­ment is opposite to the older notion, promulgated by some business schools, that the quality of a manager could be considered independent of the spe­cific activities of the managed organization.