Posted for "terrence o'neill" <troneill@charter.net>:

 Skip.
    Thanks for adding your pewrsonal experience to truth.
    The Navy learned the value of AOAs when in 1956, shocked at the crash rate
when they began landing jets on carriers at 140-mph in stead of Bearcats at 90
mph, they changed all carriers to AOAs, at GREAT expense.  It was proved worth
it, in curtting the crash rate FIFTY PERCENT the first year; and they have
refined it and kept the system ever since.
 
    Mark obviously lacks understanding of how relative wind uses an airfoil to
develop lift; and,
 how the pilot really controls his airplanes lift -- by using his pitch
control to control the ANGLE at which the wing enters the relative wind.
 
    I did a solid month of research on AOA in 1998 to write an 8-page article
for KITPLANES, starting on page 96, with encouragement of its then editor Dave
Martin, who knew very well the value of AOA, having been a back-seater in F4s
with many carrier landings.
 
    Because pilots are trained by doing, like riding a bicycle, -- instead of
by understanding in order to design an airplane to make it fly -- they are
reasonably very cautious about changing how they have come to think about
flying. EVEN IF IT IS WRONG.  Because they don't know.   In fact many of them
resent it, like Mark.   I can testify to that after trying to explain the AOA
for 40 years!  Even the head of the FAA's Safety Office I talked to, back when
Najeeb Hallaby was head of the FAA, didn't understand the AOA, and that it was
THE most BASIC instrument possible, even moreso, or equal to, the horizon.
 
    That is: a wing airfoil can produce lift and ANY speed, even one mph; and,
the wing airfoil produces more lift at greater angles; and, at some increased
angle peculiar to that airfoil, the airflow will start to break away and the
lift will drop to about half, the stall, usually occurring at between 8 to 25
degrees, depending on the sharpness of the leading edge, the airfoil
thickness, the camber, and the planform/aspect ratio/sweepback.
 
    Since sirflow is invisible, the conservative FAA still teaches tyro pilots
'stall speed', which is a secondary indicator.  That term really means the
indicated speed of stall at one G and/or weight, and can, in a C206 for
instance, vary so much as to be almost useless... depending on t/o weight.
 
    An AOA, on the other hand, enables a pilot to SEE, with his EYEBALLS, how
close he is flying his wing to its STALL AOA.  He instantly controls this
angle with his pitch control, almost as if the indicator were attached to the
elevator.
 With an AOA like the ones I made a pilot can SEE THE ANGLE accurate to a
degree, and fly the plane throuogh all kinds of maneuvers, unusual attitudes,
steep turns on Final, and so on, and avoid stalling by avoiding pulling back
too far on the pitch control.
    But if he tried this without and AOA ...it is walking along a cliff with a
blindfold on.  He can't SEE what he's doing.
 
 It is incredibly difficult to communicate these simple ideas to pilots. They
know how to work the machine pretty well, but they don't UNDERSTAND what's
happening with the air and the wing.
 Perhaps these and Skip's comments will help fix that.
 Any other comments are invited.
 T.