Avionics News January 2014 - 47

But are those capabilities enough reason to replace a perfectly good autopilot?
As one avionics shop owner put it, "In a lot of cases, customers with money to spend have to look at the situation.
Some systems are too old and limited in functions to allow
the pilot to take advantage of the new capabilities found
in the rest of their avionics package. Systems that will not
readily adapt to GPSS and cannot couple to the glideslope
to fly WAAS/LNAV/VNAV approaches are good candidates
for replacement."
There are some aftermarket upgrade adapter kits avail-

the new units like Garmin's GFC 700 or Avidyne's DFC90,
it's more about the ability to use the plethora of available
information found in the aircraft's attitude/heading reference system, or AHARS, if it's so equipped; but more on
that later.
"Really, having an AHARS provides a bunch of additional computational data that you just didn't get out of a typical mechanical system in the past," explained Dan Schwinn,
president and chief executive offer of Avidyne. "Even if
you go back to a really good autopilot like a (BendixKing)
KFC-150 or that ilk, those are good, solid attitude-based

Garmin
GFC 700

able to add some of the newer-generation features to legacy
autopilots, but the aircraft's owner needs to take a hard look
at the cost versus benefit equation.
In fact, when you consider the new capabilities, increased
reliability and a new warranty, it may just be more cost
effective in the long run to upgrade to a new system.
"It all comes down to what they are actually trying to
accomplish," the shop owner added. "Will it give them
more capabilities or, as with the decision to upgrade to
more modern radios, does the owner just want something
new?"
AUTOPILOTS: THE NEXT GENERATION
While, for many pilots, the ability to fly a better approach
or smoother straight-and-level is reason enough to give a
new autopilot consideration, those capabilities are just the
beginning of what the next generation has to offer.
And just to be clear, it's not so much that the autopilots
themselves have changed, but when you're talking about

autopilots. But as good as they are, we're talking about
units with a much lower level of sensor capabilities and
computational capabilities than those available today.
"Now we are able to use all the air data information
from the AHARS, which gives you virtually unlimited
computing capabilities. So even before you get to the cool
safety features, you can build a much better flying autopilot today."
Schwinn said that while autopilots are tasked to fly a lot
of precision maneuvers, one of the hardest tasks they have
is flying straight-and-level in dead-calm conditions.
"You can tell the difference between a good autopilot
and a great autopilot easier in dead-calm conditions than
you can in a cross wind," he said. "A good autopilot may
still wonder around a bit even in a dead-calm situation,
whereas a great autopilot will fly like it's on rails.
"This level of control requires much more complex conContinued on following page
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Avionics News January 2014

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