In this paper we investigate the utility of an explanatory and predictive account of awareness in the (re)design of complex human-computer interaction. We start by describing both the wider field of human computer awareness and the specific sub-field of situation awareness in the aviation domain. We also discuss the wide range of observations and descriptions, which detail both success and failure in the acquisition, maintenance and repair of such awareness across a range of domains. Next, we assert the need for an explanatory and predictive model of the phenomenon in the search for a reduction in the breakdowns reported and propose such a model. We then go on to investigate the utility of our model as a guide for design through the discussion of a recent experiment involving manipulations of an animated warning signal on a simulated cockpit control panel. Our results show initial support both for the model and for our earlier assertion of its utility. We conclude that our composite view of awareness yields practical benefit in the design of human computer awareness support and provides a basis for future research. (C) 2003 Elsevier Ltd. All rights reserved.