Electrooculographic measurement, fatigue and variability of performance in simulated aircraft flight

Typescript (photocopy).Recent aircraft technology has resulted in the development of aircraft with greatly increased range, flight duration capabilities and increased performance. The complexity of operating a highly sophisticated aircraft has made the problems of pilot fatigue and the associated performance decrements an issue of growing concern. The purpose of this study was to examine several components of eye and eyelid movement, using the electrooculogram (EOG) as the measurement technique. The intent was to determine whether four specific eye movement measures could be used as predictors of the subtle performance decrements due to flying related fatigue. It was also intended to determine whether subjective fatigue changes and performance decrement could be detected in tasks similar to typical Air Force pilot duty-days. Fatigue was measured with pre- and post-"flight" subjective scales and an error scoring method which scored the variability of performance (standard deviation) weighted by accuracy (mean error). These measures, along with continuous EOG, were evaluated while Air Force trained pilots "flew" a four-hour sortie in a GAT-1 flight simulator. Prior to the sortie, pilots were sleep deprived for 12 hours, after an average 2 1/2 hours sleep. The results of the data analyses were that: (1) The variability based error score was more sensitive to performance decrements than a measure used in earlier studies, (2) the subjective fatigue measures indicated a significant increase in fatigue over time and were positively correlated with the performance measure, (3) blink rate was the best predictor of performance decrements for the tracking (maneuvering) segments of the task, (4) long eye closure rate was the best predictor for the monitoring (straight and level) segments and second best for the tracking segments, (5) blink duration was a less significant predictor in both tasks, and (6) horizontal saccade velocity was not a significant predictor in either task segment. Follow-on studies being conducted by the Air Force were discussed. These studies include in-flight simulation studies and the AFTI/F-16 tests to develop the fighter aircraft of the future. Recommendations were made to re-evaluate the Air Force crew duty-day schedules which have not kept pace with advancing aircraft technologies