On Jul 29, 9:48 pm, Dudley Henriques wrote:
On Jul 30, 12:03 am, "JR Weiss" wrote:



Dudley Henriques wrote:
Unfortunately, the "experts" in the Transport Category Airplane
world have deemed AOA readouts as superfluous. Their argument
(among others) is that optimum AOA for any particular operation is
not constant for a large range of gross weights, so Vref or V2 as
defined by the FAA and other regulatory agencies is "better."

After 20 years of aircraft carrier operations and 11 years of
airline operations I tend to disagree, but I'm not an
aerodynamicist...
I've heard the same thing from the airline industry, and I think they
might have a point. I've always wondered how you guys handle the vast
differences in gross weights you have when you arrive at the initial
approach fix.
The Navy as we both know, requires a very stable approach profile so
AOA is great for them, as it automatically compensates for the
differences in approach weight and the approach is the same AOA
regardless of weight. But this assumes a fairly (or at least
comparatively anyway) narrow gross weight for the Navy when arriving
for the approach on the boat.
You guys in the majors deal with what could loosely be described by a
Navy fighter pilot as a fair to middling gross weight range on
approach. My guess would be that using an optimum AOA on approach
might very well not be as viable as using a Vref. I would of course
bow to your better judgment on this since you have time in the big
boys and I don't.
I remember seeing a report from Boeing a while back where they were
"discussing" the addition of AOA to the approach equation both with
adjusted procedures and panel changes regarding instrumentation.
If I remember right, the bottom line on their research was that the
front offices and chief pilots of various majors couldn't reach a
consensus on the issue strong enough to warrant a major policy change
at the top level. There were specific lines who were willing to have
their panels equipped with a change from a peripheral AOA indicator to
a prominent place on the glass for an AOA tape on the approach mode,
but I never followed this through enough to discover were if anywhere
everybody went with all this.

I still believe that AOA is a more sensitive indicator of performance
than IAS at relatively low airspeeds. That may actually be the
"problem" though -- we probably don't want transport pilots pumping the
yoke to keep an "optimum" AOA and get the passengers upset...

OTOH, the range of handling differences between a "light" (33,000 lb)
and "heavy" (36,500) A-6 on the ball and a "light" (170,000 Kg) and
"heavy" (302,000 Kg) 747 are quite different (I won't address the A-4,
because it wasn't a "heavy" in any sense of the word). The A-6
differed mainly in power response on the G/S, but the 747 differs
mainly in the flare. While AOA was critical in the A-6 to keep the
hook at the proper angle of dangle to snag the 3-wire, the 747 can be
landed comfortably anywhere in the nominal 3000' landing area (first
1/3) of a typical runway.

OTOOH, I think a "real" AOA indicator would be VERY helpful in escape
maneuvers for WindShear and Terrain warnings. The stick shaker is a
useful On/Off switch for backpressure, but a trend indicator via AOA
would be much more useful.

It's an interesting subject and I'm sure in any end analysis, aoa
could be integrated into the heavy environment. more than it has been.
Personally I like aoa. I've always taught wing and energy management
flying from Cubs to high performance singles.
The future may very well reveal the benefits of aoa to a wider cross
section of the commercial community. Hope so anyway! :-)
DH

Referring to sims, I found the AoA indicator of scientific interest
to measure airfoil performance, but in shooting landings I relied
on the IAS (knots/hr) and vertical airspeed indicator(feet/minute),
those together give a rough idea of angle of descent, and one
then gets a feeling of AoA from pitch.
What might be considered is an instrument that can provide all
that info in nice clear form on single gauge at a glance, let's
design it.
Ken