"Turbine-powered airplanes don’t crash very often these
days, so when they do we should all take notice. Upon reviewing such
accidents from the past few years, it’s clear there is a disturbing
trend in modern cockpits: pilots struggle to control the airplane after
the autopilot suddenly quits flying. Now before you start bemoaning the current
state of stick and rudder skills and urging all pilots to start
flight training in a Cub, let’s consider another option.
Can you
recover if George walks off the job?
Air France 447 is probably the best-known accident,
since it garnered non-stop news coverage and the airplane wasn’t found for
almost two years after it went down in the Atlantic Ocean. While the accident was complicated, the short version
is that the autopilot kicked off at night, in IMC, over the ocean, and the
pilots proceeded to stall the airplane and fly it stalled all the way to the sea.
The important lesson is that the pilots were not in the loop. When
suddenly forced to fly the airplane, they did not have the situational
awareness or the training to handle it.
Another accident, and one that received less attention,
involved a Pilatus PC-12 in Florida. The final report is not complete yet, so
all the details aren’t known, but it’s clear that the pilot lost control of the
airplane in IMC and it crashed nearly straight down. The question is why? One
plausible theory is similar to the Air France accident: the airplane, at near
gross weight after making a fuel stop, was climbing through 25,000 ft. in the
clouds when the autopilot disconnected due to turbulence.
The Pilatus has a stick shaker that will disconnect
the autopilot at high angles of attack, and the slow speed required to climb at
FL250 plus the convective weather in the area could have caused exactly
that. This is not unique to the PC-12 – most autopilots will disconnect if
the turbulence gets bad enough.
If he did lose the autopilot, the single pilot,
who was relatively new to the airplane, may have simply lost control in the
clouds. I’ve been in a similar situation and it’s quite unnerving, as you go
from monitoring the autopilot to flying (often with no flight director) in an
instant. You do not have long to get the airplane under control.
None of this is to suggest that autopilots are
dangerous, or that they should be avoided. Modern autopilots are nothing short
of amazing, and I firmly believe they increase safety. For example, single
pilot IFR is certainly possible without an autopilot, but the safety margins
are thinner. If you have an autopilot, you should use it. If you don’t have an
autopilot, you should add one.
But even the most ardent autopilot supporter has to
admit they have limitations. And in some critical situations, like the
accidents described above, autopilots essentially throw up their hands and say
to the pilots, “your airplane!” There is no warning that the autopilot may be
about to shut off and no in-between state: it’s there one second and gone
the next.
One response to this could be to design autopilots
that react better, and some pilots have advocated this approach. Theoretically,
autopilots could have some type of fall back mode, where they don’t
disconnect completely, but revert to basic attitude hold. Better
annunciators are another option, where the autopilot explains why it
disconnected and whether it can be turned on again.
Some of this may be possible, but a far more practical
(and more affordable) option is for pilots to regularly practice this failure scenario. Call
it unusual attitudes for modern airplanes – we need to experience what it’s
like to be unexpectedly thrust on stage. I had never done it myself until very
recently, and in talking to a number of other pilots, I haven’t met one yet who
does this on a regular basis. We all practice emergency scenarios that are
exceedingly unlikely to happen, like engine failures, and yet we ignore a
scenario that has proven to be both possible and fatal.
The best way to practice autopilot unusual
attitudes is to go up with an instructor or safety pilot and fly like you
would on a real trip. Put on the hood and engage the autopilot, then have your
co-pilot randomly disconnect the autopilot, both straight and level and in
turns.
Be realistic – if you spend a lot of time with your
head down, looking at your iPad, practice recovering from this position.
Staying in the loop is a critical part of the exercise, since many of us may
relax in cruise flight and may not be spring-loaded to fly.
In particular, it’s the transition that counts.
Many instrument pilots feel a little uneasy when they first transition from VMC
to IMC, especially if they haven’t flown lately. The same is true with
autopilots: the key is
those first few seconds after you lose the autopilot.
It’s basic attitude flying, and the focus should be on
flying the airplane and nothing else. Also consider that the autopilot may have
disconnected due to an AHRS or air data issue (as in the case of Air France),
so it’s a time to rely on your profiles. What power setting and what pitch
attitude lead to straight and level? You should know that cold.
Curmudgeons may scoff at this as another sign that
modern avionics have made us all bad pilots. But I think that’s an
overreaction. Even the best new technologies still have quirks to learn
and new procedures to practice. Nobody argues that celestial navigation is
better than GPS simply because a GPS receiver can fail and stars don’t.
The trade-offs are worth it. Practising autopilot
failures is just part of being a safe, modern pilot who embraces all the tools
available. Don’t just read about it in the manual – get out there and fly it!"
FLY
SAFE!
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