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The objectives of this study were to: validate a multidimensional measure of display clutter for advanced head-up displays (HUDs) incorporating enhanced and synthetic vision systems (EVS/SVS); assess the influence of HUD configuration on pilot perceptions of display clutter and flight performance; and model clutter scores in terms of visual display properties. Eighteen pilots flew a flight simulator in a landing approach using three different sets of HUD configurations (low, medium, or high clutter). Pilot ratings of overall display clutter and its underlying dimensions were recorded along with flight performance measures (deviations from localizer, glideslope, altitude and approach speed). A display image analysis software application was used to measure the visual properties of HUDs. The multidimensional measure of clutter showed internal consistency with high correlations of overall perceived clutter. Calculated clutter scores were sensitive to the various HUD configurations and in agreement with prior display classification (based on the new measure). There was a trend for the extremes of display clutter to cause less stable performance. High clutter displays were associated with cognitive complexity of flight tasks and low clutter was associated with a lack of display information. Multiple linear regression models of perceived clutter were developed based on HUD visual properties.