Masters Theses

Date of Award


Degree Type


Degree Name

Master of Science


Aviation Systems

Major Professor

Richard J. Ranaudo

Committee Members

Frank G. Collins, Rodney C. Allison, George W. Masters


Technologies have developed within the last ten years to allow the Helmet Mounted Display (HMD) to be much more effective as an air-to-ground (A/G) weapons cue. HMD A/G accuracy and performance requirements should be added to the Joint Helmet Mounted Cueing System (JHMCS) specifications, detailed to be as good or better than the FA-18 heads-up-display (HUD). Because of target ranging and line-of-sight (LOS) errors, the JHMCS is only used as an area sensor cue in the urban close air support (CAS) role. Therefore, for use against point targets, improvements to JHMCS are needed. LOS errors have to be reduced from the current 13-mil error, which would equate to +/- 260 feet from a 20,000 ft slant range. To decrease this error, more accurate helmet trackers must be used with faster update rates. HMD Earth referenced symbol update rates, which are currently restricted to 20 Hz, must be increased to allow the helmet to provide accurate information, despite aggressive maneuvering or operations in a turbulent environment. Accurate ranging sources must be developed to enhance the target elevation algorithm in the FA-18 to ensure usable target data, once designations are made. During turbulent flight conditions, the difference between the actual target position on the ground and the unstable target designation (TD) diamond depicting it cause motion differences, which distract the pilot. Methods to filter the movement of earth-referenced symbols should be explored, as well as increasing JHMCS symbol write rates. Additionally, vibration levels during low-level flight and moderate turbulence levels make HMD A/G aiming and designation tasks very difficult. Buffet suppression algorithms are used during vibrations in the air-to-air (A/A) aiming role and should be implemented for A/G use as well. The purpose of this study is to focus on present capabilities with JHMCS. The author’s tactical experience has been achieved on the FA-18 A-F variants and tactical applicability will be directed to that platform. While most references to helmet displays will center on lessons learned from the JHMCS, helmet mounted display experience was gained while serving as an exchange officer with the UK Royal Air Force and evaluating the Guardian HMD system. The analysis contained within this thesis is based on the operational insights of operating within the demanding Close Air Support (CAS) environment and the tactical enhancement that has been demonstrated with the use of Helmet Mounted Cueing systems. Currently, JHMCS is available to about half the FA-18 fleet and operational assessments, resulting from its use in the Iraqi conflict, has accelerated the demand for increased capabilities to this target cueing device. Lessons learned from the current generation of HMDs will play a major role in the design of the cockpit for the Joint Strike Fighter (JSF).

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