Subject: [NEXTEL-1] AIR TRAFFIC APPLICATIONS: FAA Moves Ahead With Plans for Satellite-based Air Traffic Management

From: [email-masked]
Date: Wed, 05 Nov 2003 01:42:18 -0500

AIR TRAFFIC APPLICATIONS: FAA Moves Ahead With Plans for Satellite-based
Air Traffic Management

Nov 01, 2003

The Federal Aviation Administration has taken a number of recent steps
to implement its plan to have GPS satellites be the primary means of air
navigation.  The opportunities for companies supplying avionics and
ground systems to make this vision a reality should accelerate in the
coming years.

In July, the FAA "commissioned" the Wide Area Augmentation System (WAAS)
for instrument flight use.
WAAS is designed to enhance the accuracy and reliability of GPS and
transmit horizontal and vertical guidance signals. The commissioning of
WAAS is the first step toward opening pilot access to 500 published
satellite runway procedures at more than 200 U.S. airports.

Pending certification of avionics with vertical navigation capabilities
and approval of individual approach procedures, pilots will be able to
navigate as low as 350 feet above the runway end under instrument flight
rules using satellite navigation to provide stable vertical guidance.
The FAA expects to publish a new procedure before the end of the year
for the full capability of WAAS, resulting in approaches down to 250
feet above the runway.

"Commissioning WAAS moves us closer to realizing the aviation potential
of GPS and the precision it can add to the world's safest and most
complex airspace system," said Secretary of Transportation Norman Y.
Mineta. Added FAA Administrator Marion C. Blakey, "Once avionics are
certified to receive the system's full capability, WAAS will allow
precision instrument approaches at thousands of runways at airports and
airstrips that have little or no ground-based landing capability. WAAS
will also provide improved en route capabilities because pilots can fly
more direct and shorter routes without depending on ground-based
navigation aides."

WAAS-compatible avionics equipment is available for the aviation
community to purchase, the FAA explained. Later this year, these
avionics systems will be further certified to receive WAAS vertical
navigation capability, the agency said.
In addition, the FAA is working with Honeywell [NYSE: HON] on developing
the Local Area Augmentation System (LAAS), which is designed to improve
the accuracy of GPS for takeoffs and landings at airports.

Under Phase I of the LAAS contract, valued at $16.7 million, Honeywell
will provide the software and hardware design of the Category I
precision LAAS. Phase II and III contract options, which total an
additional $340 million, cover the development and production of the
Category I system. Category I precision landing provides a level of
service in poor weather conditions down to a ceiling of 200 ft. and
visibility of one-half mile.

FAA explained that if the Phase II option of the contract is exercised,
the first Category I LAAS will be installed at Chicago O'Hare; Houston
Intercontinental;

Juneau, Alaska; Memphis, Tenn.; Phoenix; and Seattle airports. The first
system is scheduled to be operational by late 2006.
Once implemented, LAAS will enable pilots to guide planes safely into
busy airports in bad weather using GPS.
The FAA identified the following benefits of LAAS:

A single LAAS will provide precision landing service for most runways at
an airport;
Approaches that will avoid obstacles, restricted airspace, noise
sensitive areas, or congested airspace can be transmitted directly to
each equipped aircraft;

LAAS can be installed at some airports where conventional landing
systems cannot be used because of space or radio frequency spectrum
constraints.

WAAS Basics

The WAAS provides augmentation information to GPS/WAAS receivers to
enhance the accuracy and reliability of GPS position estimates. The
signals from GPS satellites are received across the National Airspace
System (NAS) at widely-spaced wide area reference stations. Each
reference station relays the information, via a terrestrial
communication network, to WAAS wide area master stations. The master
stations use the information collected by the reference stations to
develop corrections to the GPS position information. These corrections
are sent to a ground uplink station where they are transmitted in the
form of a WAAS correction message to geostationary Earth-orbit (GEO)
satellites. These GEOs broadcast the WAAS message to users across the
continental United States, and portions of Alaska, on the same frequency
as GPS. The WAAS broadcast message improves GPS signal accuracy from 20
meters to approximately 1.5 to 2 meters in both the horizontal and
vertical dimensions, allowing more efficient arrival, enroute, and
departure operations.

Additionally, WAAS provides indications to GPS/WAAS receivers of where
the GPS system is unusable due to system errors or other effects, such
as the recent solar flares that disrupted communications on Earth.
Further, the WAAS system is designed to strict safety standards - users
are notified within six seconds of any issuance of hazardously
misleading information that would cause an error in the GPS position
estimate.

The July commissioning of WAAS moved the FAA directly to lateral
navigation/vertical navigation (LNAV/VNAV) and localizer precision with
vertical guidance (LPV) capabilities using WAAS. Both LNAV/VNAV and LPV
approaches use the accuracy of the WAAS signal to include vertical
(glide path) guidance capability. This capability allows for improved
instrument approaches to include vertical (glide path) guidance to an
expanded number of U.S. airports.

The implementation of LPV approaches further improves precision approach
capability to users. LPV approaches are designed to exploit the tighter
satellite signal protection limits from the WAAS. This approach combines
the LNAV/VNAV vertical accuracy with lateral guidance similar to the
typical instrument landing system (ILS). The use of LPV capitalizes on
the accuracy of the WAAS signal and will result in lower approach
minimums. There are currently seven LPV approach locations in the U.S.,
and production will continue until all qualified airports have an LPV
approach at each runway end.

WAAS is also a component of the FAA's required navigation performance
(RNP).  WAAS can provide stringent RNP for required navigation (RNAV)
performance to all classes of users throughout the NAS. As air traffic
management becomes more global, the WAAS concept can be applied to civil
aviation infrastructure worldwide, enabling global safety improvements.
Also, with more stringent RNP standards, inefficiencies in airspace
utilization could be reduced, thus increasing traffic flows and avoiding
delays.

The FAA said it is working toward final operational capability (FOC) for
WAAS to include a full compliment of WAAS GEOs, which will ensure that
each receiver sees at least two GEO satellites at all times throughout
continental United States and most of Alaska. The FAA is also working
with Canada and Mexico to expand the WAAS coverage area to support North
American implementation of WAAS.

As GPS is modernized, WAAS will take advantage of GPS improvements,
including addition of the L5 frequency. The FAA is adding L5 to the
current WAAS GEOs. The FAA is also working with the International Civil
Aviation Organization, which supports the development of standards and
procedures for satellite navigation for civil aviation applications
worldwide.
--Fred Donovan

(Tammy Jones, FAA, 202/267-3883)

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