Elucidation of crew communication aspects is required to improve the manman interface which supports operators' diagnoses and decisions. Experiments to clarify operator performance in emergency situation were performed using a training simulator. The operator performance was evaluated from the viewpoint of crew communications. The following four approaches have been tried to evaluate operator performance. (1) Crew performance are quantitatively evaluated by number of tasks gained by operator

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... w. (2) The group thinking process was clarified by cognition-communication flow. (3) The group response process was clarified by movement flow. (4) Quantitative indexes for evaluating crew performance are represented by the amount of information effectively exchanged among operators. Crew communications in emergency condition were categorized into four types.