T o d d P a t t i s t writes:

The direct sensation of acceleration is reliable, but like
the instruments has imperfect accuracy.

A sensation of acceleration alone is of limited utility. Unless you
can integrate the accelerations over time in a very accurate way, they
don't tell you much about where you are, or what attitude you are in.

The integrated
value of acceleration that you do in your head produces an
estimate of speed, and that value is less reliable. The
second integration that you do in your head is position, and
that value is even less reliable.

Yup.

I've been trying to give you the benefit of the doubt, but
you're not trying hard to understand this. Perhaps this
will make it clear - A full motion simulator can produce an
excellent simulation of many of the sensations we are
discussing. It's obvious that the full motion simulator
does not move thousands of feet the way that an airplane
does. How does it achieve excellent simulation without
moving out of the simulation box? It can do that because
humans are good at sensing accelerations, but not in
integrating them to get velocity or double integrating to
get position. The full motion sim matches the accelerations
pretty closely, but not so closely that it needs to really
leave the building that houses the sim.

The same thing happens in instrument flight and in VFR
flight - the pilot uses the sensed accelerations to fly, but
uses the horizon - either real or AI instrument simulated to
recalibrate his awareness of position and attitude. Without
the horizon, his beleif in position and attitude starts to
drift away from reality. He's excellent at detecting when
he starts to accelerate away from his current
position/attitude, but lousy at knowing what the current
position/attitude is.

So it would seem that the only utility of sensation is in assessing
extremely short-term movements of the aircraft. You may sense that
you've started to climb or descend, but you don't know how far, or how
fast. For movements and commands that take place over the scale of
seconds, that might be moderately useful, but beyond that it seems
that it's just good for feeling warm and fuzzy.

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