This article is classified "Real"
Training professional pilots, regardless of whether those pilots will end
up flying F-15s for the USAF or 747s for KLM, is extremely expensive. One
way of controlling costs is the extensive use of full-motion virtual
reality flight simulators [1].
Virtual reality flight simulators have become very similar to reality in
the visual domain, but have obvious limitations when it comes to simulating
movement: if you integrate all the accelerations your simulated plane seems
to be doing, you end up traveling the distance the plane would if it were
actually flying [2].
The part of your inner ear that measures acceleration is only briefly
stimulated by the start of a movement in the simulator; the rest is done
visually, which works because the visual system, having acquired extensive
real-world experience, is capable of generating the same sensations as real
accelerations [3]. Moreover, your neural system is capable of learning,
and quickly at that: in a flight simulator, especially a military one
where maneuvers are much more extreme than in a civilian simulator, the
pilot learns within an hour to associate visual movement with only very
little input from the inner ear.
When the pilot next happens to accelerate in the real world (and it
reportedly has happened just quickly walking down the stairs after a
simulator session) his system revolts [4] because of the cognitive
dissonance caused by conflicting actual input and experience. Not a
good idea at Mach 0.8 and 50 meters above the tree tops. Fortunately,
one un-learns (or, rather, re-learns) within a day or two.
[1] Because computers and hydraulically-movable platforms are cheaper
than real aircraft, although you wouldn't know it from sitting in
coach on a 737.
[2] This presents problems when using a stationary simulator.
[3] Anyone who has seen an IMAX presentation of the JPL-produced Venus
and Mars fly-overs will attest to this.
[4] The exact nature of this revolt is left as an exercise for the reader.