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

Abstract

In the contextual complexity of modern, computerised systems, thecurrent system state can come as an unpleasant shock to even anexperienced user. In this paper, we show that errors, which occur withinsuch complexity, cannot easily be described in terms of individual tasksand their component actions. We use this starting point to examine thedominant 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 humanfactors involved. We then show the existence of a deeper problem, whichwe identify as a knowledge gap (Johnson, 1992) between operator andsystem. We next assert the existence of a second, higher level ofactivity, which encompasses the strategies used by operators to managetasks within a complex, changing environment. We show that the knowledgegap identified arises as the result of a failure in such a strategy anddevelop a new design solution, based on this reclassification. We thenevaluate this new approach through the redesign of interfaces in asimulation of a well-documented air-incident. The results of ourevaluation show the redesign to be significantly less prone to thedepicted error. We conclude by considering the implications of theseresults in terms of our knowledge-based approach.