Helmet-mounted display symbology for ground collision avoidance in fighter aircraft

Abstract

A two-part experimental simulation study was performed to examine ways of improving Ground Collision Avoidance Systems (GCAS) for fighter aircraft through the use of Helmet-Mounted Display (HMD) symbology. Modality and information presentation issues were addressed through the design and testing of five display formats. An audio alert with no visual symbology was used as a baseline. The addition of visual alert symbology was tested using a head-fixed iconic alerting cue. Formats for additional recovery information were tested using an aircraft-fixed guidance cue, a head-fixed guidance cue, and a head-fixed guidance cue with a pitch ladder. Subjects were given audio and visual side tasks and then responded to GCAS alerts. Recovery performance and subjective ratings of the displays were recorded. Lower reaction times were observed when a head-fixed visual alert was given in addition to the standard audio alert. No significant differences were seen in subject recovery performance, measured by altitude loss and response times. However, subject head motion varied significantly with display type. Subjects tended to fixate on guidance and state symbology when it was provided. This led to cases where pilots performed entire recoveries with their heads offboresight when using head-fixed guidance symbology. Subjects varied in their preference of symbology, but head-fixed guidance and state information was preferred over the other display categories using the Analytical Hierarchy Process.