The HUD – Heads Up Display – provided crucial data to pilots when the Space Shuttle glided home for landings.
The Space Shuttle was a combination space craft and glider. It was launched into space thanks to two solid rocket boosters plus an external fuel tank that helped fuel the Shuttle’s three main engines. Once in reached zero gravity in space, the size and weight of the Shuttle wasn’t an issue.
Landing was accomplished by firing its Orbital Maneuvering System thrusters to decelerate and re-enter the Earth’s atmosphere. In higher atmosphere the shuttle used a reaction control system and then as it descended it was controlled by “fly-by-wire” hydraulically actuated flight surfaces.
All in all, a neat trick for a 110-ton “glider.”
The pilot/commander also had the advantage of a Heads Up Display (HUD) system that has become a major boon to pilots, particularly of military aircraft and more modern airliners.
The HUD is an optical mini-processor that displays flight data on the glare shield. Without taking his/her eyes off the view of the horizon, the pilot can stay up to date on crucial information. This keeps pilot situational awareness high.
During a crucial phase of descent like shuttle landings – there’s no opportunity for a “go around” – the less the pilot is distracted by shifting his vision, the better.