Some aviation users and all nonaviation users were given access to the U.S.
Federal Aviation Administration's satellite-based navigation signal as of Aug.
24, and key decisions about the future capabilities of the US$3 billion system are expected to be made by early September, government and industry officials say.
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 said.
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 the extra 50 feet is worth the extra cost," he said.