A Quantitative Evaluation of Pilot-in-the-Loop Flying Tasks Using Power Frequency and NASA TLX Workload Assessment

While all manner of both qualitative and quantitative assessment tools exist to measure pilot performance during aircraft flight test, the argument to mathematically correlate two such diametrically different metrics is strong. By definitively connecting a pilot’s written handling qualities or task loading feedback with measured performance data, researchers can more accurately examine any of a whole host of flight research topics.

Building upon past research which shows a positive correlation between Cooper-Harper Handling Qualities Ratings and calculated values for power frequency using a group of experienced test pilots, it is valuable to examine whether power frequency correlates with other metrics such as the NASA Task Loading Index (TLX). TLX provides a measure of a pilot’s self-assessed workload and is routinely used in modern flight test experimentation to measure perceived pilot workload.

Using data from twenty-nine instructor pilots flying the NASA Ice Contamination Effects Flight Training Device (ICEFTD), the data set examined showed little connection between power frequency values and the TLX scores assigned by the pilots to each approach. Among the group of pilots flying the ICEFTD, self-assessed workload was a poor indicator of measured work load – such a trend indicates that non-test pilot self-measurement in workload assessment may not be as valuable as trained test pilot measurements. A number of influential causal factors were evident in the use of this recycled data set, and an ideal retest scenario is discussed at length.