Effects of FOV and aircraft bank on pilot head movement and reversal errors during simulated flight

Background: Recent studies have shown that while flying under Visual meteor ological conditions (VMC) pilots tilt their head to keep the horizon stabil ized on their fovea. This reflex, referred to as Opto-Kinetic Cervical Refl ex (OKCR), may improve spatial awareness by establishing the horizon retina l image as a stabilized primary visual-spatial cue. Since the limited field of View (FOV) provided by helmet-mounted displays (HMDs) significantly dec reases visual stimuli, the purpose of this research was to determine how re duced FOV affects head movements. Hypotheses: As FOV is decreased, there wi ll be a significant reduction in OKCR-induced head movement. Reduced FOV wi ll also increase control reversal errors. Methods: Twelve pilots completed simulated flight tasks in a stationary dome. Head tilt, pitch, and yaw were examined as a function of aircraft bank and FOV(40 degrees, 60 degrees and 100 degrees circular). The number of control reversal errors was analyzed to investigate signs of spatial disorientation. Results:During VMC manuever s pilots exhibited significant OKCR; however there were no significant diff erences among the three levels of FOV. FOV significantly affected head pitc h movements under both VMC and instrument meteorological conditions (IMC). Pilots yawed their heads in the direction of aircraft bank under VMC. Pilot s committed 22 reversal errors out of 72 trials (30.55%). The magnitude of the error was largest for the 40 degrees FOV condition. Conclusions: Pilots exhibit the OKCR under all tested levels of FOV and also make head yaw mov ements in order to keep the way point in sight during banking maneuvers. Pi lots demonstrated stick reversal errors when transitioning from following a lead aircraft under both VMC and IMC conditions.