Avionics News November 2016 - 30

WAAS GPS NAVIGATORS
TSO-C146b-approved navigators allow pilots
to use these space-based navigators as their
sole source of guidance, both en route, in terminal airspace and in instrument approaches.
And this capability finally fulfills the promise of
the global positioning system dating back to the
early 1980s.
Approaches possible using an approved WAAS
GPS navigator come in different flavors and
utility levels - and none require more ground
infrastructure beyond appropriate lighting.
The most highly rated, most coveted of the
approach options are called LPV approaches -
lateral precision with vertical guidance. LPV approaches deliver accuracy levels exceeding that
of the gold standard of instrument approaches,
the venerable instrument landing system. Approaches using GPS tend to be more stable and
unaffected by ground conditions, weather or
terrain variations - as we know ILS approaches
can be.
Today, WAAS GPS-based instrument approaches now number in the thousands. As of
mid-August, the FAA reported that more than
3,700 LPV approaches were available - several
hundred more than there are ILS approaches.
Furthermore, more than half of the LPV approaches serve runway ends previously lacking
a precision-approach option.
Beyond precision approaches, these same
WAAS GPS navigators also serve up a more
accurate, more stable platform for GPS-based
alternatives to thousands more nonprecision
approaches - VOR, localizer and, in particular,
NDB approaches.
But it takes a GPS navigator approved under
TSO-C146b paired with the appropriate guidance indicator to use these approaches. q

ADS-B OUT

Continued from page 29

That's one benefit continuing to grow as more
operators opt for approved WAAS GPS navigators.
Meanwhile, more pilots are opting to install ADS-B In,
the FAA's "carrot" to the final rule's mandated "stick."
ADS-B In provides immediate and tangible operational
benefits - particularly for pilots of aircraft lacking
several safety-enhancing cockpit utilities: specifically,
live traffic, almost-live satellite-based weather radar
and access to a host of other weather information -
nationwide and airport-by-airport. And the aircraft can be
fitted with ADS-B In independently of ADS-B Out.
Admittedly, a WAAS GPS navigator-based solution
puts compliance costs at the upper end of the range.
They gain access to thousands of WAAS GPS-based
instrument approaches (see sidebar).
But for those who can do without precision GPS
approach capabilities, many other less-expensive
options exist today. ADS-B Out options available now
let an aircraft meet the mandate at costs under $3,000 -
installed.
They cover, at a minimum, all the ADS-B Out
requirements - and can't be used for primary navigation
like a WAAS GPS navigator. Many are stand-alone
boxes lacking any additional bells or whistles; some also
provide some or all ADS-B In services, either available
only on the pilot's tablet or others capable of providing
their data on a cockpit-installed display.
The original option: Approved position
source plus broadcast avionics - or
something else
The earliest solutions, as previously noted, all
depended on a WAAS GPS navigator.
Mate an approved position source with a broadcast
system and there it is - your aircraft is ADS-B Out
compliant. That broadcast system may be an add-on
to an existing transponder with integral Out broadcast
capabilities, with or without an integral WAAS GPS
engine for position data.
Today, pilots and owners may choose between a
solution mating a blind position receiver with an ADS-B
Out transponder - 978 MHz, some with integral ADS-B
In receiver using the same frequency - called a UAT or
Universal Access Transceiver - or a 1090 MHz Mode S
Continued on page 32

avionics news

november

2016

Table of Contents for the Digital Edition of Avionics News November 2016