"A Boeing 747 is not really an airplane, but five million parts flying in close formation."
Even if no one knows who once said this sentence, it is a great metaphor to picture how modern airplanes were, and still are, complex machines that require a tremendous amount of manual effort to manufacture and assemble.
Complete automation is nowadays still not possible for mainly two reasons.
First, due to the small lot size of parts leading to high robotic systems programming costs, and second because automation is not practical in many cases, especially where high dexterity and perception of a human are required.
Not only that, manufacturing processes were over time becoming more and more complex. People in the factories were required to use an increasing amount of information in their jobs, much of it coming from CAD systems engineering designs.
While PC screens were occasionally used to indicate the next step in a process or a part's position, assembly guides and templates used on the factory floor were most of the time in a paper format. A significant source of expense and delay in airplane manufacturing when they had to be updated with engineering design changes.
For all of these reasons, Thomas Caudell and his colleague David Mizell were asked to come up with an alternative to the expensive systems used to guide workers on the factory floor.
... with an "augmented" solution.
After some thought, the two Boeing employees realized that if factory workers were able to directly access digital CAD data when performing manufacturing or assembly operations, several sources of expense and error would be eliminated.
Their idea was to provide a “see-thru” goggles system to the factory workers that can augment their visual field of view with useful and dynamically changing information. They finally came up with was a heads-up display headset, called “HUDset”, combined with head position sensoring, and workplace registration systems.
As Thomas Caudell and David Mizell explained in their study "Augmented Reality: An Application of Heads-Up Display Technology to Manual Manufacturing Processes", this technology is used to "augment" the visual field of the user with information necessary in the performance of the current task, and therefore we refer to the technology as “augmented reality".