Near-infrared spectroscopy (NIRS) has emerged as an easily manageable non-invasive method for the continuous monitoring of cortical oxygenation during various cognitive tasks including mission flights of helicopters. This study evaluated effects of auto flight control system (AFCS) on pilot’s prefrontal cortical responses during flight using NIRS. Four male test pilots volunteered in this study to perform an in-flight examination of a light scout and observation helicopter, OH-1. Each pilot performed 12 sorties including 6 instrument flights and 6 level turn flights, with and without AFCS. During the flight, oxyhemoglobin (O2Hb) was continuously recorded from right side of the forehead using NIRS. Mean O2Hb concentration changes　 (⊿O2Hb) from the baseline before the starting maneuver were calculated at each flight task (e.g. instrument flight, left and right turns). The ⊿O2Hb was significantly lower in the flight with AFCS (mean± SD of 2.13±1.54 μmol･L-1) than that without AFCS (3.35±1.40 μmol･L-1). There were significant AFCS effects to keep ⊿O2Hb lower level during the level turn in the 2 less experienced pilots with 190 and 30 hours OH-1 flying. While the experienced pilots with 1,800 and 1,360 hours of OH-1 flying showed higher AFCS effects on the instrument flight. The present results showed the NIRS provides enough sensitivity to monitor prefrontal activation during helicopter flying maneuvers. They also suggested the AFCS may reduce the prefrontal O2Hb induced by the cognitive demand during the flight.

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