AOPA Pilot Magazine - April 2014 - 14

WAYPOINTS

BY THOMAS B. HAINES
Editor in Chief

Before the magenta line
Two decades of GPS guidance

EDITOR IN CHIEF

Thomas B. Haines
has been writing
and reporting for
AOPA Pilot since
1988-and flying
since 1977.

14 | AOPA PILOT April 2014

AN IMPORTANT ANNIVERSARY passed in mid-February
without fanfare. Today we fly GPS-guided flight plans
from right after takeoff through the cruise phase, into
the terminal area, and down the instrument approach
without much thought, enjoying precise lateral and vertical guidance to within in a couple of hundred feet and
a half mile of the runway in all sorts of weather; it's all
kind of humdrum. But just 20 years ago GPS approaches
were cutting edge stuff-and not very slick, either.
February 13, 2014, marked the twentieth anniversary of the Garmin GPS 155 receiving FAA Technical
Standard Order (TSO) authorization. With that the GPS
155 and its monochromatic text display became the first
device to meet FAA TSO C129 A1 standards, allowing
a pilot to navigate by GPS through all phases of flight,
including-most important-through a non-precision
instrument approach procedure. GPSs for en route IFR
use had been around for a few years, following closely
on the heels of the approval of IFR lorans.
And while the idea of flying a GPS approach using
a text display and a swinging needle seems quaint
(or perhaps frightening), this was the culmination of
years of work by the FAA and the industry. A group
of pilots at AOPA and a Beech Bonanza A36 owned
by the association led a testing program with the FAA
Technical Center that paved the way for IFR GPS as far
back as 1992. The Bonanza was sent to the FAA center in Atlantic City for a major installation of test gear,
including a tracking ball on its belly that allowed an
old Nike air defense radar and missile guidance system
to latch onto the airplane from afar to watch its progress through a series of test flights. An FAA technician
worked a pallet full of gear in the back while another
sat in the right seat to oversee the pilots from AOPA and
elsewhere as they flew hundreds of approaches, guided
by a Northstar M2 IFR Loran/GPS.
The testing was a moderate success, identifying
numerous software changes needed to help pilots fly
the procedures more accurately. In addition, the signal
monitoring showed the need for additional corrections
to the GPS signal in order to get position information
precise enough to fly something close to precision
approach minimums, which was the ultimate goal.
After the creation of the TSO and much testing, the
FAA declared GPS ready for prime time shortly after
the Department of the Defense announced GPS initial
operational capability in December 1993. Garmin shot

out the door with the certified GPS 155 only a couple
of months later and the race was on for air superiority
among various GPS manufacturers. Some in the competition-such as Northstar, Magellan, and Trimble-don't
exist anymore, at least not in the aviation space.
I remember heading to Garmin's headquarters
near Kansas City to fly one of the very first IFR GPS
approaches ever in Garmin's Mooney. The flight was
inspirational and later that year, when I spec'd out
the equipment for our 1994 Better Than New 172
Sweepstakes project airplane, a GPS 155 was at the
top of the stack. With the gear installed in the summer of 1994, we flew then-FAA Administrator David
Hinson and the media on IFR flights to Runway 5 at
Maryland's Frederick Municipal Airport, one of the first
GPS approaches in the system.
The desire for precision approaches-with vertical guidance-continued as the FAA moved forward
with the Wide Area Augmentation System (WAAS), a
combination of ground and satellite-based signals that
provided the GPS receiver in the airplane with a correction factor to improve the accuracy of the signal,
allowing more precise guidance.
While that system was in development, Garmin
and others continued to evolve their product lines. The
Garmin GNS 430 came out in 1998, combining for the
first time an IFR GPS with a VHF communication transceiver and VHF navigation receivers for VOR, localizer,
and glideslope-and the all-important moving map and
its now familiar (and relied upon) magenta line. When
WAAS was finally declared operational in 2003, a new
phase of development occurred, allowing for vertical
guidance to or near Category I minimums. Without the
need for ground transmitters, the FAA moved ahead
quickly with the development of hundreds of new
instrument procedures to many more runway ends,
improving safety and access to many airports.
Following along on a day-to-day basis, development of the air traffic control system seems glacial, but
viewed from the perspective of a couple of decades,
the advancements are significant and quite monumental. Our flying will never be the same again-and thank
goodness for that.
AOPA
EMAIL thomas.haines@aopa.org

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AOPA Pilot Magazine - April 2014

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