FAA opens up WAAS

Some aviation users and all nonaviation users were given access to the Federal

Aviation Administration's satellite-based navigation signal as of Aug. 24,

and key decisions about the future capabilities of the $3 billion system

are expected to be made by early September, government and industry officials


The FAA decided to make the Wide Area Augmentation System signal available

to aviation users to increase situational awareness while on an airport

surface and while flying under visual flight rules — when instruments are

not required to overcome poor visibility. Nonaviation users include boaters

and hikers. The decision came after prime contractor Raytheon Co. performed

a 21-day test of WAAS' ability to offer a continuous, reliable signal.

WAAS is a network of ground reference stations that improve positioning

information from Global Positioning System satellites and send that data

to aircraft.

During the most recent tests, WAAS demonstrated its ability to provide

pilots with horizontal accuracy of 1 meter to 2 meters and vertical accuracy

of 2 meters to 3 meters throughout the continental United States, the FAA


During similar tests last year, WAAS accuracy was found to exceed expectations,

but other software bugs were discovered in Raytheon's system. Tests of the

system's integrity — its ability to verify that the information it provides

is correct — found that WAAS may provide misleading and hazardous information

to pilots.

An independent panel was established early this year to research solutions

to the integrity problem. Unless WAAS meets the requirement of only one

failure in 10 million operations, it cannot be certified for use in safety-critical

applications. Initial operating capability is planned in 2002, a two-year

delay from the previous estimate.

FAA's WAAS program manager Dan Hanlon said he expects decisions to be

made based on the panel's findings within a few weeks. The panel is trying

to find technical solutions that will allow aircraft to use WAAS to get

within 200 feet above the runway and a half-mile away.

The panel has offered several ways to get that capability, but it will

be expensive and will require Raytheon to redesign some of its WAAS architecture,

said Doug Helton, vice president of air traffic services and technology

for the Aircraft Owners and Pilots Association. The decision will be "whether

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