Effects of primary flight symbology on workload and situation awareness in a head-up synthetic vision display

The primary flight display - and primary focus of attention - in modern fighter aircraft is a head-up display (HUD). This is becoming true also for newer transports in the U.S. Air Force inventory. Some human factors issues associated with synthetic vision in a head-down display are different from those associated with a head-up synthetic vision display, especially when the displays are used as primary flight references. Among these issues are the use of color, ability to see through the display, symbology clutter, compatibility between head-up and head-down displays, and attentional factors. This paper reports the results of a study in which HUD-experienced pilots flew simulated complex precision approaches to landing in three visibility conditions, with and without synthetic terrain, using either pathway-in-the-sky symbology or more traditional military standard HUD symbology. Workload and situation awareness measures were collected to determine the relative workload associated with these conditions and if, as has been proposed elsewhere, flying a pathway-in-the-sky display is associated with "cognitive capture". or a decrease in situation awareness concerning things other than the pathway.