Practice & prescription of work on the flight deck 1 The prescription and practice of work on the flight deck Peter Wright Department of Computer Science University of York York YO10 5DD, UK pcw@cs.york.ac.uk +44 1904 432742 Steven Pocock Department of Computer Science University of York York YO10 5DD, UK stevep@cs.york.ac.uk +44 1904 433384 Bob Fields Department of Computer Science University of York York YO10 5DD, UK bob@cs.york.ac.uk +44 1904 434755 ABSTRACT Technological change has led to the proceduralisation of flight deck work. Yet accidents attributable to pilot error still occur. CSCW studies of work suggest work as prescribed does not always reflect work as practised. While one might expect this to be less true of safety critical settings like the flight deck, the case studies we present provide support for this distinction. We present two re-framings which better capture the status of procedures on the flight deck. One case study illustrates what else is required in order to make procedures work. The second illustrates how procedures are customised. Instead of seeing them as prescriptions of work we view them as resources for action and boundary objects. We discuss design implications of this re-framing KEYWORDS Pilot error, CSCW, procedures, practices, resources for action, boundary object, due process. INTRODUCTION There have been many technological advances in the commercial aviation industry. A modern aircraft is now capable of automatic flight practically from take off to landing. For the humans on the flight deck, this technological advance has been associated with dramatic changes in the nature of their work and in particular an increasing proceduralisation of their work practice. Much of the human work on a flight deck is prescribed by so called standard operating procedures (SOPs), which are typically defined by aircraft manufacturers or operators. On all flight decks SOPs are represented in printed form in a so- called quick reference handbook (QRH) and in the more modern aircraft, they are also represented as pages on an electronic display. A QRH will include procedures for carrying out tasks conceived by the designers including both normal procedures such as landing checklists and procedures especially designed for dealing with emergencies. Viewed from outside the cockpit SOPs are understood as prescriptions of work and pilots are expected to follow them whenever possible. Yet, pilot error is still one of the most often cited contributing factors to aircraft accidents. In a recent CAA study of 447 global fatal accidents, 76% involved a crew primary causal factor. (CAA 1998). Such statistics raise the question why