Pilot cueing is a valuable use of Head Mounted Displays (HMDs) as it greatly helps the user to visually locate electronically identified targets. It is well known that a target which is hard to spot in the sky can be easily tracked and studied after it has been visually located. Transients, including sun glint, can reveal much about distant targets as they are visually studied. This is implicit in the Visual Rules of Engagement . The term Virtual Beyond Visual Range has been coined to reflect the fact that optimized HMD cueing can extend visual identification to ranges previously covered only by radar data. The visual acquisition range can drop by a factor of three, however, when HMD image correlation errors expand the uncertainty zone a pilot must visually search. We have demonstrated that system errors, tolerable for off axis missile targeting, can produce this large drop in operational effectiveness. Studies using the Spectron SE1430 HMD analysis system have shown that errors of this magnitude can develop in current HMD models, and that these errors were neither identified by ready room tests nor were they correctable in the cockpit. The focus of this study was to develop affordable techniques to quantify the relationship of combat effectiveness to HMD defects for this and other advanced operating modes. When combined with field monitoring of HMD degradation, this makes economic optimization of the HMD supply/maintenance model possible while fulfilling operational mission requirements
