Beyond Mode Error: Supporting Strategic Knowledge Structures to Enhance Cockpit Safety

In the contextual complexity of modern, computerised systems, the current system state can come as an unpleasant shock to even an experienced user. In this paper, we show that errors, which occur within such complexity, cannot easily be described in terms of individual tasks and their component actions. We use this starting point to examine the dominant thinking in this field (Palmer, 1995, Palmer et al, 1993, Degani et al, 1996, Rushby 1999). We show this dominant position, which suggests that much of this ’automation surprise’ (Palmer 1995) results from mode error, is a fundamental misclassification of the human factors involved. We then show the existence of a deeper problem, which we identify as a knowledge gap (Johnson 1992) between operator and system. We next assert the existence of a second, higher level of activity, which encompasses the strategies used by operators to manage tasks within a complex, changing environment. We show that the knowledge gap identified arises as the result of a failure in such a strategy and develop a new design solution, based on this re-classification. We then evaluate this new approach through the redesign of interfaces in a simulation of a welldocumented air-incident. The results of our evaluation show the redesign to be significantly less prone to the depicted error. We conclude by considering the implications of these results in terms of our knowledgebased approach.