AEA Pilot's Guide 2020-2021 - 38

WAAS WAY DO I GO?
Continued from page 37

approaches with LPV minimums. Hall is a former U.S. Air
Force F-16 pilot and wing commander who also led the New
York Air Guard.
"I'm never happy about one-deep anything where flight
safety is involved - ask Boeing," he said referring to the
recent 737 MAX accidents where MCAS software triggered
nose-down trim based on data from a single faulty angleof-attack sensor. "My current preference is to fly a WAASbased GPS approach displayed on the primary flight display
(Garmin in his Mooney) and a backup CDI displaying the
ILS. Or if I'm flying an ILS on the primary flight display, the
synthetic vision displays WAAS for situational awareness.
With both operating full up, both are terrific. But one nice
feature of ILS is the closer you get to the runway, the closer
you get to the transmitter antenna." Hall said he wants both
GPS and ILS as a distributed system at Ithaca because one
can't be interfered with by either the Department of Defense
or the Chinese.
The Department of Defense can interfere with GPS
during military exercises as highlighted in NOTAMs, and the
Chinese have been known to jam GPS in China.
Trescott finds ADS-B to be a lifesaver. "I like ADS-B a lot
more than I thought I would. Rather than looking at it now
as an unnecessary, expensive burden, I see it providing
a lot of information. I see call signs of different aircraft out
there when ATC calls out traffic; I see the call sign they are
referring to, and I'm aware of what is going on around me."
He also likes the patented absolute and relative vectors
provided by Garmin that shows not only the heading the
aircraft is on, but the relative vector of the other aircraft
headed his way relative to his own. "You can determine if
the airplane is going to pass in front or behind of you based
on the trajectories of the two aircraft relative to each other,"
he said. "So you know if the traffic is going to be a factor or
if you don't have to worry about it."
At Carpenter Avionics Inc. based at Smyrna/Rutherford
County Airport 12 miles south of Nashville, President Mark
Lee is a fan of WAAS for navigation. "It is beneficial for
aircraft owners and pilots to have the capability to fly WAAS
LPV, otherwise there may not be an instrument approach
of that caliber at an airfield," he said. But he adds that LPV
capability is more relevant for instrument-rated pilots than
for VFR-only pilots.
Carpenter Avionics serves a full spectrum of customers

from owners of piston aircraft to turboprops, business jets
and helicopters. "We see a lot of interest in LPV capability
from business jet operators," he said.
"One thing about WAAS GPS technology, you are
required to have that sensor to meet the ADS-B mandate,"
he added, such as with a transponder operating on either
1090 MHz or UAT on 978 MHz. The big question is whether
to equip with GPS WAAS to meet the ADS-B Out mandate
versus also enabling GPS WAAS LPV and LP capability. In
many cases, the only reason for an aircraft owner to have
GPS WAAS in the airplane is to meet the ADS-B mandate.
"The folks we talk to have usually done a fair amount of
homework on this and are already reasonably opinionated
about it, but we share our insights with them," Lee said. He
notes it is still possible to upgrade a GNS 430 or 530 with
WAAS. A Garmin official said the current cost, which hasn't
changed in a year, is $4,495 and the company quotes a
seven to 10 business day turnaround. This is more than
twice what it cost a decade ago when the offer was first
made on the massively popular 430 and 530 units with GPS
but without WAAS. Lee said this 430 or 530 upgrade will
reduce the cost of a transponder by about $500 to $800
since it would no longer need to have WAAS built in to meet
the ADS-B mandate. If WAAS is not in the transponder,
it has to be somewhere else in the aircraft. He said the
Garmin GTN series and Avidyne IFD440, 540 and 550 GPS
nav/comm units all have WAAS built in.
There is a market for used 430 and 530 units, and some
avionics companies have trade-in programs for customers
who want to upgrade to new systems.
Lee thinks upgrading a 430 or 530 to WAAS makes
sense when meeting the ADS-B mandate so it will be
possible with optional ADS-B In reception to see ADS-B
traffic, weather and also fly RNAV LPV approaches. Only
45% of aircraft that could be equipped for ADS-B have
been upgraded so far, he said. Lee also has customers
who are swapping out vacuum type attitude indicators and
directional gyros for solid-state electronic flight displays (like
the ones Aspen Avionics makes) that are not prone to failure
like the old equipment.
In the Northeast, Chris Bergman at Columbia Air
Services Inc. at Groton-New London Airport in Connecticut
serves everyone from the weekend warrior who flies VFR
in a Cherokee or a Bonanza to owners and operators of
single-engine turboprops. Some of the recreational fliers
install GPS WAAS with vertical guidance, and all of them
try to do something with ADS-B. He services about 100

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