The NASA Task Load Index As A Measure Of Pilot Workload In The Commercial Transport Environment

This paper examines the usefulness of the NASA Task Load Index (TLX), a multidimensional rating procedure, in subjectively assessing the overall aircrew workload. There is evidence that nothing is gained by using weighted averages from individual bipolar rating scales to generate a single rating for overall workload. A similar, reliable assessment can be developed from several of the individual bipolar rating scales.

During a joint simulation study conducted by Douglas Aircraft Company and Boeing Commercial Airplanes, NASA-TLX scores were collected from pilots in simulated commercial transport operations. Both normal and emergency conditions were programmed to a Phase II certified B-727, six degree-of-freedom motion-base simulator. Correlation and factor analyses of the bipolar ratings were computed to determine the overlap of the different rating scales within the NASA-TLX. In addition, the bipolar scales were compared to the computed Weighted Workload Score to determine the sensitivity of the measures to the manipulation of task demands.