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The effect of optical blur on simulated IFR approaches
Background:
Most of the research on near visual acuity and pilot performance has concentrated on the effect optical blur has on the readability of navigation charts. In order to determine how reduced visual acuity could affect other aspects of pilot performance, we investigated the effects of optical blur on simulated instrument-flight-rules (IFR) approaches.
Methods:
Simulated IFR approaches were performed under 4 different levels of optical blur by 15 instrument rated pilots. The simulator resembled a single engine aircraft with basic IFR instrumentation. Light levels were selected to represent both day and night time flight conditions.
Results:
The majority of the subjects maintained adequate control of the aircraft to the decision height under all levels of optical blur. The root-mean-squared values for the localizer position during the inbound phase degraded significantly at the worst acuity levels of 0.78 and 0.90 logMAR under daytime conditions. However, RMS values under nighttime conditions were not significantly affected by optical blur. The major effect of reduced near acuity on IFR approaches was the inability to resolve the detail on the approach plates and radios.
Conclusions:
The major decrement in performance as a result of reduced near acuity is the inability to read the approach charts and radio settings. If this information is provided to the pilots, then they should be able to continue successfully the IFR approach to the decision height.