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 The NASA researchers reexamined the 37 accidents included in the safety study to determine the most common decision errors and any themes or patterns in the context within which the errors occurred. NASA found that the most common decision errors occurred when the flight crew decided to "continue with the original plan of action in the face of cues that suggested changing the course of action." The NASA study stated:

Clearly, more cognitive effort is needed to revise one's understanding of a situation or to consider a new course of action than sticking with the original plan whose details have already been worked out.... It appears that evidence must be unambiguous and of sufficient weight to prompt a change of plan.

With regard to ambiguity and its effect on situation assessment and decisionmaking, the NASA study stated:

Cues that signal a problem are not always clear-cut. Conditions can deteriorate gradually, and the decision maker's situation assessment may not keep pace...a recurring problem is that pilots are not likely to question their interpretation of a situation even if it is in error. Ambiguous cues may permit multiple interpretations. If this ambiguity is not recognized, the crew may be confident that they have correctly interpreted the problem. Even if the ambiguity is recognized, a substantial weight of evidence may be needed to change the plan being executed.

The study noted that stress may limit the pilot's ability to properly evaluate the situation: Reaching decision...requires projection and evaluation of the consequences of the various options. If pilots are under stress, they may not do the required evaluations.... Under stress, decision makers often fall back on their most familiar responses, which may not be appropriate to the current situation.

Further, the NASA study determined that organizational and social pressures may contribute to the high incidence of "plan continuation errors" by creating goal conflicts, which may result in decision errors in the face of ambiguous cues and high-risk situations. The study noted that organizational and social factors that have the potential to create goal conflicts with safety include pressure for on-time arrival rates, fuel economy, and avoidance of diversions to reduce passenger inconvenience.

The NASA study concluded that, to reduce pressures on pilots, operators "must be willing to stand behind their pilots who take a safe course of action rather than a riskier one, even if there is a cost associated." The study noted that integrated flight displays that present up-to-date information on dynamic variables, such as weather and traffic, could reduce the ambiguity of events flight crews might encounter and that training to help flight crews develop "strategies for choosing a course of action" would be beneficial.