In an effort to address some of the fundamental issues that must be considered in any long- range progression from `targeting' to `flight instrument' for any helmet-mounted display (HMD), this study investigated the impact of incorporating an HMD with one of the objective flight performance tasks used in head-up display (HUD) evaluation. The task, an unusual attitude recovery, was adapted to require head movement by having the pilot acquire a target either on- or off-axis prior to initiating a recovery. Experiment One did not include any HMD orientation symbology and established the increase in reaction time 0.82 seconds for the on- axis condition to 1.35 seconds for the extreme off-axis condition (+/- 90 degrees off-axis with a +30 degree head tilt). Experiment Two included minimal HMD orientation information in half of the trials. In trials where no HMD symbology was presented, initial reaction times significantly increased (i.e., from 1.06 for on-axis to 1.56 seconds for +/- 80 degrees). In trials where pilots were provided minimal HMD orientation information off-axis, initial reaction times did not significantly increase (i.e., 1.06 on-axis to 1.12 seconds for +/- 80 degrees).
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