The most valuable lesson we learned from all emergencies and accidents is the danger of complacency. Once we think we are sitting comfortably with everything organized that is the time to watch out. We will be caught out by the unexpected and the unpredicted – particularly, the human responses. We can never afford to be totally satisfied, no matter how much time, money and effort we have expended.

Investigations following accidents and emergencies have often highlighted the inadequacy of si...