Flight Training - January/February 2024 - 53

Yet an autopilot can show us how to cut to
the chase.
In a Cessna 172 Skyhawk at a safe
altitude with the autopilot engaged in
altitude hold, reduce the throttle to idle
and wait for the airplane to decelerate
to your target speed, say 65 knots. Then
add enough engine power to keep it
there. Stabilize for a minute or two and
note the results. It'll probably be something
like a 3-degree nose-up attitude
and 2,100 rpm.
Whenever you're in a Skyhawk and
want to fly slow, you'll know the shortcut.
The approximate pitch and power required
are known values, so you can go right to
them. Getting it just right requires fine
tuning based on aircraft weight, density
altitude, and other factors, but these autopilot-aided
numbers provide a baseline.
AUTOPILOTS NEVER
GET TIRED, CRANKY, OR
IMPATIENT.
Modern autopilots provide even more
information to instrument pilots.
Bruce Williams, an aviation writer
and flight instructor living in Seattle,
Washington, suggests using the cameras in
our smartphones to create " panel selfies "
to set metrics.
" We've all snapped photos of the
scenery and our happy faces as we fly, "
Williams said. " Why not a panel selfie?
It's quicker than scribbling figures in
flight and far easier to read the next day. "
Williams suggests pilots record panel/
engine monitor photos when:
* Flying straight and level in high-speed
and economy cruise.
* In cruise climb.
* In cruise descent.
* Being vectored for an approach.
* On final while the autopilot tracks
lateral and vertical guidance.
In the 1989 Beechcraft Bonanza A36
Williams flies, he typically tracks the ILS
glideslope at about 110 knots at a power
setting of 17 to 18 inches of manifold
pressure, approach flaps, and landing gear
down. If he's on autopilot and controllers
ask him to speed up, he simply adds
power, and his airplane accelerates while
still following the glideslope.
Similarly, internal logic built into the
autopilot shows the optimum intercept
angles, and how to make heading
corrections.
If the localizer is offset to the right,
for example, the autopilot momentarily
banks right, levels the wings, and collects
the localizer needle. Then a modest heading
change to the left holds the corrected
heading.
" I teach my instrument students to try
to do what the autopilot does so well, " he
said. " Make a slight turn, level the wings,
then correct again before the localizer
needle is completely centered-and stay
coordinated throughout the process. "
Sophisticated autopilots can automatically
perform feats that no sane
pilot would even attempt. How about
a 90-degree intercept of an ILS at 220
knots just outside the final approach fix?
No human pilot can reliably pull off that
trick, yet autopilots do it reliably-and
they roll out of the turn exactly on course
no matter the wind.
Autopilots never get tired, or cranky,
or impatient. They break from time to
time, so they must be closely monitored
(and correctly programmed).
Modern versions are designed by
some of the brightest engineers in the
aerospace industry, and those people have
made a science out of replicating the best
practices of human pilots over time.
It's long been a stinging insult to
say that a pilot flies " mechanically. " But
today, there's certainly no shame in flying
like any other modern, digital autopilot.
In fact, it would mean we fly smoothly,
predictably, and decisively, and that we
seldom make mistakes and absolutely
never fuss or complain.
Now that's something to aspire to. FT
dave.hirschman@aopa.org
FLIGHT TRAINING JANUARY/FEBRUARY 2024
53
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Flight Training - January/February 2024

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