Abstract
Workload assessment has become a common part of system evaluation. Workload assessment is an important adjunct to performance measurement because the operator is sometimes flexible enough to disguise excessively demanding systems by expending additional effort to overcome optimal information processing limits. This is often referred to as the problem of determining a “workload redline.” The present paper recounts an evaluation of a proposed redesign of the KC-135 tanker aircraft cockpit. The current KC-135 cockpit has three crew positions: pilot, copilot, and navigator. As part of a proposed redesign, modern automation capabilities to replace the navigator were considered. Ten operational KC-135 crews and two KC-10 crews were studied while performing missions of differing levels of workload in a high-fidelity simulator. Three main classes of data relevant to the redline issue were collected: Performance data. Subjective Workload Assessment Technique (SWAT) ratings, and Subjective WORkload Dominance (SWORD) ratings. Evaluation of the performance results demonstrated that the redesigned cockpit could be flown in accordance to regulations. This was a necessary first step, but could not ensure that acceptable workload had been obtained. Taken together, the SWAT and SWORD results strongly suggested that acceptable performance can be achieved at acceptable level s of workload. In conclusion, the present study is a prototypical example of using available assessment tools to determine system acceptability. These tools should be useful for many other system evaluations.
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