Tuesday, 25 August 2009

Boundaries of acceptable performance

Paul Shanahan congratulated me on my 'courage' (cf. 'Yes Minister') in using the original version of Rasmussen's 1997 contours of safe operation diagram. He was right, the diagram is very hard to communicate. Rob Miles has used Venn diagrams in a way that complemented Rasmussen's contours, and so I have devised some Miles-Rasmussen diagrams to illustrate the effects of technology, management and regulation.

In the first instance, the operating envelope is bounded by the limits of Crew Resource Management, business performance, and safety (plus environment and security). Note that this last limit is blurred, unlike the others. Going outside the operating envelope results in unsafe operation, crew overload or unacceptable business performance.

The sales pitch for technology

The sales pitch for technology is that it extends the boundary for safety, giving an extension to the operating envelope, and "look how small the unsafe operation area is now". This is of course nonsense.

Technology is probably neutral, and can be visualised as just making the whole space bigger. This does not mean that actual operation is safer; it might stay at the boundary of safe operation, but with improved business performance.

Generative management

Generative management (cf. Ron Westrum) does increase the operating envelope; this picture ties in with Rob Miles' diagrams showing that good management does not see safety and business performance opposing each other.

Zealous regulation

Tightening regulation (with everything else staying the same) leads to a smaller operating envelope and a big increase in the potential for 'violations'.

There is some more to come on how 'nudge' regulation could be made to work via the internet. Not today, though.

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