Flight Training - March/April 2025 - 48

ADVANCED PILOT CAREER PILOT
AUTOPILOT-BLESSING OR CURSE?
AUTOMATION AWARENESS IS KEY
BY PETER A. BEDELL
feet when the airplane violently pitched
down about 45 degrees " in an instant. "
He rightly chopped the throttles to idle
and disconnected the autopilot, but it
took both arms to move the yoke aft. Once
under control, he saw that there were
seven units of nose-down trim input.
Reducing the airspeed was critical in this
case for regaining control of a severely
out-of-trim condition.
The postmortem with the avionics
AN AUTOPILOT, WHEN OPERATED
properly, is a blessing to pilots. It can
take care of flying tasks, freeing pilots to
shift their focus to other items, such as
writing down a clearance or inputting a
flight plan into a GPS navigator or tablet.
When it works properly and a pilot has
thorough knowledge of its operation, an
autopilot is a highly useful tool. In fact,
at the airlines, inoperative autopilots are
often a no-go item as they are required
for flight in reduced vertical separation
airspace from FL290 to FL410.
Automation accidents in aviation are
more common than one might think,
however. They are often fatal too. An
underlying problem is pilots' reliance on
automation and unfamiliarity with the
equipment and how it operates. Pilots
should be extremely familiar with the
system and know how to test it safely on
the ground before taking off. This to confirm
it does what it's supposed to do and,
perhaps most important, that you know
all the ways to turn it off if it's not doing
what it's supposed to do. My first airliner
training for a 29-seat turboprop BAe
Jetstream had us recite from memory the
48
FLIGHT TRAINING MARCH/APRIL 2025
12 ways to disengage the autopilot. Good
advice that I won't forget.
The number one culprit in automation
accidents is the autopilot controlling
the pitch-trim system. Imagine having
an invisible hand moving the pitch trim
without your knowledge. Pitch forces
grow behind the scenes until the autopilot
can't hold it anymore. When it gives
up, you're stuck in a rodeo ride with a
severely out-of-trim airplane. And usually
the bigger the airplane, the harder the fall.
Think of those two tragic Boeing 737 Max
8 crashes in 2018 and 2019 that killed 346
people and were the result of a runaway
trim system. Newer autopilots have trimin-motion
warnings to alert pilots that
something is not right. Those with older
autopilots might want to rest their knee-
or occasionally their hand-against the
trim wheel for movement awareness. In
light airplanes that are so equipped, I place
a big red collar around the pitch-trim circuit
breaker as a last line of defense to cut
power to an errant pitch-trim servo.
Automation plays a role in light airplanes
mishaps, too. A Beechcraft Baron
pilot was cruising on autopilot at 8,000
shop revealed the pitch servo for the
autopilot had a voltage fault causing a slow
nose-down trim movement. The autopilot
dutifully held altitude until it reached its
load limit and handed off the airplane-
with a built-in disaster-to the pilot. The
older model autopilot only had a small,
black needle in a not-too-obvious location
to depict trim, with no light or aural
warning. After the incident, the owner
upgraded to a newer model.
In situations like the Baron incident
and 737 Max crashes, controlling
airspeed is critical. The higher the
airspeed, the more power the trim has.
An out-of-trim condition can effectively
lock the controls at high speed. In the
cases of the Max crashes, the airplanes
were at such high airspeed, pitch control
was essentially impossible as the airplanes
were allowed to accelerate to and
beyond the redline. The Baron pilot's
pulling the power to idle was critical to
his survival.
Autopilots are a tool in a pilot's chest.
But do not rely on them. Hand-flying
skills and a raised eyebrow of awareness
are still essential to being a good
pilot. Flight instructors half-jokingly
like to say that students try to kill them
multiple times a day, and the same could
be said for autopilots, especially those
that connect to the pitch trim. Know the
system, keep an eye on its behavior, and,
in the words of Ronald Reagan, " trust,
but verify. " FT
PETER A. BEDELL is a pilot for a major
airline and co-owner of a Cessna 172 and
Beechcraft Baron.
ALEX WILLIAMSON
Flight Training - March/April 2025

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