"Some assembly required." This phrase strikes fear into the heart of every parent faced with putting together a bicycle on the eve of a kid's birthday. But it's also an intimidating fact of life for manufacturing firms-perhaps none more so than aircraft makers, whose employees must often piece together bewildering assortments of parts using volumes of jumbled instructional verbiage. Wouldn't it be nice if these complex transportation systems could tell an assembler how to put them together?

For some airplane-factory workers, certain plane parts can do just that, with the aid of augmented reality (AR). This technology melds virtual-reality viewers or other visual displays with positional trackers and ever smaller and faster computers to provide real-time assembly instruction. Unlike virtual reality, in which the user is completely immersed in an artificial world, AR lets you see the real world as well as an additional overlay of information that appears attached to the workpiece itself.