Effects of in-flight field-of-view restriction on rotorcraft pilot head movement

The work reported in this paper examines the effect of restricting visual field-of-view (FOV) on rotorcraft pilot head movement. To simulate the FOVs of current and future helmet mounted displays (HMDs) used for night vision pilotage, a FOV restrictor was attached to the helmets of the test subject pilots. The restrictor limited horizontal FOV to 100, 80, 60, 40, and 20 degrees. Ten test subject pilots executed a set of low altitude flight maneuvers in an instrumented NAH-1S helicopter at the NASA Crows' Landing Airfield Head movement was measured with an IR head tracker for those pilots who flew in the rear seat and by a video camera for those who flew in the front seat. Test data indicated that pilots responded to restriction sin horizontal FOV by changing their pattern of head movement, both in azimuth and elevation. These compensation strategies change as FOV decreases and vary from pilot to pilot. Test results reported in this paper, in conjunction with referenced data outlining FOV effects on flight performance, handling qualities, and visual cue ratings, give visionic system designers and users predictive information on pilot workload and performance.