Background: Orbiter landing data show decrements in pilot performance following spaceflight compared to preflight simulated landings. This study aimed to characterize pilot head-eye coordination during simulated orbiter landings, and relate findings to microgravity-related spatial disorientation.
Methods: Orbiter landings were simulated in an A340-300 simulator flown by six pilots. Turns about the Heading Alignment Circle (HAC) to align the orbiter with the runway were simulated by 45 degrees banking turns. Final approach was simulated with an 11 degrees glide slope from an altitude of 4267 m, with preflare at 610 m and touchdown at 200 kn. Orbiter landings were also performed in the Vertical Motion Simulator (VMS) at NASA Ames by a NASA test pilot.
Results: A340: During the HAC maneuver the head and eyes rolled toward the visual horizon with a combined gain of 0.14 of bank angle. Pilots alternated fixation between the instruments and the runway during final approach, almost exclusively focusing on the runway after preflare. Optokinetic nystagmus was observed during rollout. VMS: Head and eye roll tilt when rounding the HAC were of similar magnitude to that observed in the A340. During final approach the Heads-Up Display (HUD) reduced pitch head and eye movement.
Conclusions: Roll tilt of the head and eyes during the HAC tended to align the retina with the visual horizon. Overlaying critical flight information and the approaching runway with the HUD reduced pitch head and eye movement during orbiter final approach in the VMS relative to the A340 (no HUD installed).