The cockpit of NASA's Gulfstream GV with a synthetic vision system display. Several different HUD elements are visible, including the combiner in front of the pilot. The green 'glare' in the lower right corner of the combiner is a result of backscatter of off-axis light from the projection unit, as well as reflection from ambient light in the flight deck. Because the combiner has a pronounced vertical and horizontal curve to help focus the image, compensation is applied to the display symbols to make them appear flat when projected onto the curved surface. When not in use, this combiner can swing up and lock in a stowed position. The Projector Unit in the Gulfstream GV image would be directly above the pilot's head.