US transportation secretary Norman Mineta and Federal Aviation Administration chief Jane Garvey are allowing the troubled Wide Area Augmentation System (WAAS) to move ahead after the all-clear from a group of independent experts.
Just a year ago, the FAA was unsure whether the approach and landing system "was worth supporting" following technical problems, including excessive false alarms, which halted WAAS acceptance testing.
The group, including a WAAS Integrity and Performance Panel and an Independent Review Board (IRB), formed by the Institute for Defense Analyses and Mitre, were brought in to assess the technical risks. They concluded that Raytheon's $500 million WAAS contract should not be terminated since integrity issues with the WAAS signal are being resolved.
WAAS is designed to ensure the accuracy and integrity of global positioning system (GPS) signals. Originally to be commissioned in 1998, the FAA said last year that it would not be able to deliver even limited WAAS approach guidance capability until 2002.
The IRB and Raytheon believe a safety-certificated WAAS is achievable by early 2003, but Steve Zaidman, the FAA's research and procurement chief, is more cautious, and has set a September 2003 deadline for the initial service - lateral and vertical navigation (LNAV/VNAV) - with full capabilities to follow in several years. LNAV/VNAV provides approach guidance down to a 350ft (105m) decision height. The IRB says WAAS "should more than meet its initial requirements" and it sees "no serious technical barriers".
FedEx Express Boeing 727-200 freighter is the first commercial operation to carry out precision approaches using a satellite landing system (SLS) with a local area augmentation system (LAAS). The SLS approach procedures - at FedEx's Memphis International Airport hub - are flown straight into Category 1limits, but "more advanced" precision approaches will be cleared in due course, according to Pelorus Navigation Systems, manufacturer of the Honeywell/PelorusSLS-3000 installed at the airport.Source: Flight International
