Head-up display symbology for ground collision avoidance

Four ground collision avoidance displays were tested using a fixed-base T-38 simulator with a projection screen and simulated head-up display (HUD). When given a standard Break-X, pilots were able to spend only 40% of the flight time between desired altitudes and crashed in 20% of the runs. Horizontally- and vertically-moving chevron symbols allowed 70% and 80% of the flight time to be spent at the desired altitude respectively and resulted in a crash in 8% of the runs. A preview depiction using a perspective elevated surface at the desired altitude was the best display for the task investigated, allowing 90% of the time to be spent at the desired altitude with a crash rate of 2%