The OKCR and Pilot Performance during Transitions between Meteorological Conditions Using HMD Attitude Symbology

Research has shown that spatial disorientation often occurs when pilots transition between real-world visual cues and head-down attitude instruments. Recent studies investigating the opto-kinetic cervical reflex (OKCR) indicate that when pilots transition between these two types of visual cues, they are also transitioning between frames of reference. Limited research has been conducted investigating pilots' response during transitions between real-world visual cues and helmet-mounted display (HMD) attitude symbology. Eleven pilots performed vertical “S” maneuvers in and out of clouds to simulate frequent transitions between visual meteorological conditions and instrument meteorological conditions using both primary flight symbology on an HMD and traditional head-down primary flight instruments. Because pilots focused primarily on the symbology during the task, the OKCR was not found. Results also revealed that pilots were better able to maintain commanded vertical velocity when using the HMD compared to the head-down instruments, which is attributed to the head-up location of the symbology. Having the HMD symbology superimposed on the real-world visual scene can provide additional visual cues that pilots can use to perform their task more efficiently.