Conformal Symbology,Attention Shifts,and the Head-Up Display

Thirty-two pilots flew instrument approaches in a high-fidelity simulator. Location of flight symbology was manipulated head-up vs. head-down while controlling for optical distance and symbology format. Pilots were assigned to one of two symbology sets, conformal and non-conformal. Each pilot flew half of the trials with the symbology presented in a head-up location and half with the symbology located head-down. Airspeed tracking for both groups was displayed with non-conformal digital symbology. An unexpected far domain event was presented on one trial per pilot. The results revealed that, for flight path control, there was generally a cost associated with head-down location. The magnitude of this cost was larger for conformal than for non-conformal symbology. Head-up presentation resulted in faster transition from instrument to visual flight reference, but poorer airspeed tracking and slower response to the far domain unexpected event and greater error tracking digital airspeed. The results are interpreted with the theoretical framework of object-based and space-based theories of visual attention, and the tradeoffs between clutter of overlapping imagery and information access cost.