Paolo Amoroso  <amoroso@mclink.it> wrote:
+---------------
| Paul Wallich <pw@panix.com> writes:
| > Well, there were the stories about fly-by-wire aircraft flipping
| > upsidedown when they crossed the equator...
| 
| I heard a similar story, but the aircraft flipped upside down *in a
| simulation*.
+---------------

These may all be urban legend variations of a different story
altogether: What is certainly true is that very-low-altitude
terrain-following autopilots have code in them to, in certain cases,
roll the plane upside down when going over the top of a large hill
or mountain, so that as the plane dives back down the far side of the
hill the pilot pulls +G's [of which the human body and airframe are
both more tolerant] rather than -G's, and then rolls upright again
at the bottom of the back of the hill, of course.

The [possibly urban legend] story is that an early version of the
software would, when flying across a completely flat prairie, roll
the plane inverted then immediately upright again when it passed
over a cow.  ;-}


-Rob

-----
Rob Warnock			<rpw3@rpw3.org>
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