Symposium Presentation Plan Continuation Errors: A Factor in Aviation Accidents?

Despite efforts to design systems and procedures that support safe aviation operations, accidents still occur. Errors in human judgment and decision making have been found to be a contributing factor (NTSB, 1994). In this session we will examine the nature of decision %~oIs’~ on the flight deck and possible contributing factors. The difficult problem of identifying and defining decision errors will first be addressed. The difficulty stems from the fact that often there is no single best solution, judged by an objective criterion. An even more serious difficulty is the problem of “hindsight bias” (Fischhoff, 1975). It is easy to point fingers after the fact, identifying the errors that must have contributed to the accident. Clearly, caution must be exercised in moving from post hoc analyses to causal explanations. The research described in this symposium was motivated by a common pattern evident in a large set of Pt. 121 aviation accident reports examined by the NTSB (NTSB, 1994). About two-thirds of the decision errors identified by NTSB analysts could be categorized as “plan continuation events,” that is, decisions to continue with the original plan of action despite the presence of cues that suggested changing the course of action (Orasanu, Martin, & Davison, in press). These events are similar to what have been called “get-there-itis or “pressing on” (O’Hare and Smitheram, 1995). Traditional approaches to understanding decision errors have typically focused on cognitive limitations or biases of the human decision-maker. In contrast, a systems approach (Reason, 1997; Woods et al., 1994) mandates analyzing systemic factors that may contribute to these errors. Contextual factors include the quality ofthe available information, organizational policies or social factors, and weather, aircraft, or other situational conditions. Not to be ignored are cognitive factors such as level of relevant knowledge or experience, cognitive resources, and cognitive strategies. Personal factors include attitudes and motivation. Presentations will examine relations between plan continuation events and their potential causes. The first presentation (Martin et al.) will describe an analysis of Pt. 121 accidents that have occurred since the 1994 NTSB report. The goal was to determine whether error patterns are constant across time, despite changes in aircraft systems, flight deck design, and crew resource management training. It also examines contextual factors present in the accidents. The second paper (Burian et al.) will examine the nature of decisions that pilots make when they encounter weather, based on incident repons. Comparisons will be made between events involving Pt. 121, 135 and 91 flights. Differences in Lynne Martin, NRC/NASA Ames C. Elaine McCoy, Ohio University