Archives For Uncertainty

NASA safety handbook cover

Way, way back in 2011 NASA published the first volume of their planned two volume epic on system safety titled strangely enough “NASA System Safety Handbook Volume 1, System Safety Framework and Concepts for Implementation“, catchy eh?

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Process is no substitute for paying attention

As Weick has pointed out, to manage the unexpected we need to be reliably mindful, not reliably mindless. Obvious as that truism may be, those who invest heavily in plans, procedures, process and policy also end up perpetuating and reinforcing a whole raft of expectations, and thus investing in an organisational culture of mindlessness rather than mindfulness.

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An articulated guess beats an unspoken assumption

Frederick Brooks

A point that Fred Brooks makes in his recent work the Design of Design is that it’s wiser to explicitly make specific assumptions, even if that entails guessing the values, rather than leave the assumption un-stated and vague because ‘we just don’t know’.

Brooks notes that while specific and explicit assumptions may be questioned, implicit and vague ones definitely won’t be. If a critical aspect of your design rests upon such fuzzy unarticulated assumptions, then the results can be dire. Continue Reading…

While I’m on the subject of visualising risk the Understanding Uncertainty site run by the University of Cambridge’s Winton Group gives some good examples of how visualisation techniques can present risk.

In June of 2011 the Australian Safety Critical Systems Association (ASCSA) published a short discussion paper on what they believed to be the philosophical principles necessary to successfully guide the development of a safety critical system. The paper identified eight management and eight technical principles, but do these principles do justice to the purported purpose of the paper?

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One of the canonical design principles of the nuclear weapons safety community is to base the behaviour of safety devices upon fundamental physical principles.

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I’ve recently been reading John Downer on what he terms the Myth of Mechanical Objectivity. To summarise John’s argument he points out that once the risk of an extreme event has been ‘formally’ assessed as being so low as to be acceptable it becomes very hard for society and it’s institutions to justify preparing for it (Downer 2011).

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