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HOW A COCKPIT REMEMBERS ITS SPEEDS

Edwin Hutchins Distributed Cognition Laboratory Department of Cognitive Science University of California, San Diego

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Introduction
Thirty years of research in cognitive psychology and other areas of cognitive science have given us powerful models of the information processing properties of individual human agents. The cognitive science approachprovides a very useful frame for thinking about thinking. When this frame is applied to the individual human agent, one asks a set of questions about the mental 1 processes that organize the behavior of the individual. In particular one asks how information is represented in the cognitive system and how representations are transformed, combined, and propagated through the system (Simon, 1981).Cognitive science thus concerns itself with the nature of knowledge structures and the processes that operate on them. The properties of these representations inside the system and the processes that operate on representations are assumed to cause or explain the observed performance of the cognitive system as a whole. In this paper I will attempt to show that the classical cognitive science approach canbe applied with little modification to a unit of analysis that is larger than an individual person. One can still ask the same questions of a larger sociotechnical system that one would ask of the individual. That is, we wish to characterize the behavioral properties of the unit of analysis in terms of the structure and processing of representations that are internal to the system. With the newunit of analysis, many of the representations can be observed directly, so in some respects, this may be a much easier task than trying to determine the processes internal to the individual that account for the individual’s behavior. Posing these questions in this way reveals how systems that are larger than an individual may have cognitive properties in their own right that cannot be reduced tothe cognitive properties of individual persons (Hutchins, 1995). Many of the outcomes that concern us on a daily basis are produced by cognitive systems of this sort. Thinking of organizations as cognitive systems is not new, of course. What is new is the examination of the role of the material media in which representations are embodied, and in the physical processes that propagaterepresentations across media. Applying the cognitive science approach to a larger unit of analysis requires attention to the details of these processes as they are enacted in the concrete activities of real persons in interaction with real material media. The analysis presented here shows that structure in the environment can provide much more than external memory (Norman, 1993). I will take the cockpit of acommercial airliner as my unit of analysis and will show how the cockpit system performs the cognitive tasks of computing and remembering a set of correspondences between airspeed and wing configurations. I will not present extended examples from actual observations
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because I don’t know how to render such observations meaningful for a nonflying audience without swamping the reader intechnical detail. Instead I will present a somewhat stylized account of the use of the small set of tools in the performance of this simple task that is accomplished every time an airliner makes an approach to landing. The procedures described below come straight from the pages of a major airline’s operations manual for a mid-sized jet, the McDonnell Douglas MD-80. Similar procedures exist forevery make and model of airliner. The explanations of the procedures are informed by my experiences as a pilot and as an ethnographer of cockpits. In conducting research on aviation safety during the past 6 years,3 I have made over 100 flights as an observer member of crew in the cockpits of commercial airliners. These observations span the range of old and new technology cockpits, domestic and...