Re: A brief commentary

From:         "Rudi Vavra" <>
Organization: Goodfox Pty. Ltd.
Date:         20 Jul 96 15:59:10 
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Glenn Carroll wrote:

> I don't know what spatial disorientation you're talking about, as no
> one else has mentioned it on this thread.  Care to clarify what you
> mean here?

It is the overwhelming sensation (in the absence of other, i.e.
visual, clues) that you are not flying straight-and-level, even if
your instruments indicate that you are. Your senses can be fooling
you into thinking that you are flying upside down, or leaning to one
side, etc. The problem is, you can actually fool yourself into
believing that your instruments (attitude indicator) are faulty, and
believing your senses. A lot of pilots flew their airplanes into the
ground not believing their instruments. There is the story
of the flight of F-16s, flying in formation between two solid layers of
cloud (an overcast and an undercast), with no visual reference to the
horizon. Up ahead they saw a guy in a Beech Bonanza flying serenely
along, minding his own business. As the leader was getting a bit
bored, he rolled upside down, and the formation followed. They
overtook the Bonanza, flying upside down, as if nothing was amiss.
Sure enough, looking back, they saw the Bonanza roll over slowly on
its back :-)
(I hope they told him they were just fooling around)

That's what spatial disorientation is all about. It is a very
powerful sensation, and even very experienced pilots experience it on

> Of course the nut of the problem for Birgenair (pending the NTSB
> report ;-) is deciding which intstruments are right, and to what
> extent.  My point was that in this case the decision criteria seemed
> straightforward:  one instrument, the ASI, said "too fast", and
> another, the stick-shaker, said, "too slow".  This impasse can be
> resolved through an instrument all pilots carry with them:  "their
> ass strapped to the hardware", as someone else put it.  At a given
> throttle setting and nose attitude, a B757 is not about to suddenly
> accelerate past its airframe speed limit.  That eliminates "too
> fast" as a threat.  "Too slow" can be taken care of by a moderate
> throttle setting/pitch, and then one can start worrying about which
> instrument(s) are wrong, and what one should do next.

Aaah, but how do you know that your attitude indicator is not faulty?
What if the various attitude indicators on board also didn't agree?
See the problem? They have to identify which instruments they can


Rudi Vavra <>
(Those Magnificent Men and Their Flying Machines)
<<The beatings will continue until morale improves.>>