Helmet-Mounted display cues enhance visual acquisition of mid-air collision hazards beyond using head-up displays alone

OBJECTIVE: This study undertook an experimental comparison of visual acquisition for the avoidance of Mid-Air Collisions (MAC) when using cueing provided by Head-Up Display (HUD) and Helmet-Mounted Display (HMD) symbology. BACKGROUND: Previous work has shown that providing accurate cueing can improve visual detection performance, but no study had quantified the impact of providing cues via a HMD to reduce MAC risk. METHOD: Military fast jet pilots flew two scenarios in a Virtual Reality (VR) simulation. In one, a HUD provided cues to nearby aircraft. In the other, a HMD was used alongside the HUD to provide cues. The study measured visual acquisition range of aircraft that posed a MAC risk, as well as subjective workload, Situation Awareness (SA), gaze direction, and qualitative feedback. RESULTS: Visual acquisition occurred at a longer range when HMD cues were available compared to using a HUD only. HMD cueing was associated with lower subjective workload and higher perceived SA. Participant gaze direction indicated that HMD cues resulted in a more focused visual search. CONCLUSION: Including HMD alongside the existing HUD used in military aircraft improved visual acquisition of MAC hazards, beyond that offered by HUD alone. The clear presentation of spatially referenced cues in the HMD enabled pilots to use a focused visual search process, improved SA and reduced workload.