Re: NTSB recommend FAA to require installation of AOA system in all transport category aircraft

Date:         16 Oct 97 00:44:12 
From:         tschell@s.psych.uiuc.edu (Terry Schell)
Organization: University of Illinois at Urbana-Champaign
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Followups:    1 2
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s_odle@earthlink.net writes:
<snip>
>Why, is it any easier to fly angle of attack instead of airspeed?

Because the important AOA's (best glide, stall, etc) do not vary with
gross weight.   Finding best glide using airspeed requires knowing
your weight at that time and then using a table/computer. Stall is
even worse because you are very concerned about the effect of turns on
stall speed. You need to know actual gross weight and then compute the
force in the turn and *then* look it up in a table to find the stall
speed.  With an AOA meter you just *look* at it; it will tell you
exactly how much lift you can extract before a stall.  Any error in
calculating your weight at that moment will result in blowing both
computations when flying by airspeed.

<snip>
>Also, will the increase in level of safety (if there is any) be enough
>to offset the cost of implementing such a system in all aircraft?

The cost? Let's see...  one piece of yarn attached to the outside of a
window, a grease pencil mark on the inside for best L/D, another mark
for stall. (Just kidding there... I am just sure that the AOA gauge
will need to be electronic, triple-redundant, and integrated into the
FMC.)