FAA pushes back GPS
- By Bob Brewin
- Sep 19, 1999
The Federal Aviation Administration has delayed by 15 years its ambitious plan to begin phasing out its last ground navigation systems and to leave the satellite-based Global Positioning System as its sole means of air navigation, according to a forthcoming Transportation Department report.
The FAA now plans a more gradual approach that will retain ground-based navigation systems well into the next century, according to agency officials.
The satellite network, when fielded, will help ease the increasingly crowded air routes in the United States by enabling aircraft to fly closer but still safely. Satellite navigation also would permit aircraft to fly more direct routes and is an essential component in the FAA's free flight concept, under which pilots will have more discretion in planning routes within predetermined areas, said Jack Ryan, vice president of air traffic management at the Air Transport Association (ATA).
Ryan said the system will help alleviate airport logjams by providing for "curved approaches," increasing the number of aircraft that can land during any period. The system also will improve navigation for transoceanic routes that have radar coverage. The FAA has long maintained that enhanced GPS systems will provide the same precision and safety factors offered by today's ground-based systems at a far lower cost.
The FAA originally planned to begin phasing out all ground navigation systems beginning in 2005, with GPS becoming the sole means of navigation in 2010, based on the Federal Radionavigation Plan developed in 1996.
According to a draft version of the 1999 plan, the FAA now plans to maintain a backup network of ground systems for pilots flying with very low visibility—what is known as Category II and Category III conditions—well beyond 2010. The FAA does not plan to begin phasing final systems out until 2020, according to the plan.
FAA officials now say they will begin phasing out the ground systems three years later, in 2008. They also say the agency has not set any date for turning off its backup network and making GPS the sole means of navigation.
Technical and financial factors caused the FAA to take an evolutionary approach to its satellite navigation network plans. Software development for the Wide-Area Augmentation System (WAAS) for GPS has been slow, delaying the program during the past two years, and a lack of funding and strict oversight from Congress forced the FAA to scale back its plans, sources said.
Top FAA officials, who gave the go-ahead to the new plan at a Sept. 2 meeting, took an "ultraconservative approach" in balancing the mix of satellite-based and ground navigation systems as the agency evolves to an all satellite-based architecture, according to Dave Peterson, director of international activities in the FAA's Satellite Navigation Program Office.
Peterson said the FAA's conservative approach means that the agency will continue to operate a "basic backup network" of ground-based navigation aids—such as instrument landing systems (ILS), which pilots rely on for final approaches during bad weather—while proceeding with deployment of WAAS for GPS.
Peterson added that the new plan still represents a "a vote of confidence" in WAAS, which over the past two years has contended with software problems and cost overruns.
WAAS is designed to provide en route navigation and guidance for all but the toughest precision approaches throughout U.S. airspace. The FAA also plans to install the Local-Area Augmentation System as a replacement for high-precision ILS gear at 160 airports.
Michael Shaw, senior team leader for the radionavigation and positioning staff in the Office of the Assistant Secretary for Transportation Policy at DOT, said the decision to retain ground-based systems longer than planned reflected the FAA's response to commercial airlines and general aviation community.
Shaw said the original GPS/WAAS plans and schedules were "overly ambitious," while the new plan "represents a more measured approach."
Steve Hodges, FAA product team leader for GPS products, said the decision "re-affirmed the agency's commitment to deploy satellite navigation."
The agency's ultimate goal still is to use GPS-based satellite navigation technology as the primary and sole navigation service for aviation, he said. But he added that it is difficult to predict when this will occur, particularly because technology is changing so quickly.
"One of the mistakes we made in the past was that we were unrealistic and overly optimistic as far as how soon we would [be able to] transition," Hodges said.
Robert Jackson, manager for FAA air traffic management systems programs at WAAS contractor Raytheon Systems Co., said he believes the new FAA WAAS plan shows the agency has "a high degree of confidence" in the capabilities of the complex WAAS architecture.
Peterson said the top-level FAA endorsement of WAAS followed Raytheon's successful completion of a nonstop, eight-day demonstration of the software in mid-August. The successful test means the FAA now can meet its goal for an initial operational capability for WAAS to support nonprecision approaches in the fall of 2000, Peterson said.
The ability of WAAS to support some types of precision approaches has been delayed until 2002 or 2003, Peterson said.
The FAA plans to start reducing its ground-based navigation aids to a basic system between 2008 and 2013, Peterson said.
The U.S. airline industry solidly backs the FAA's evolution to a satellite-based navigation system, said Ryan, adding that the "horrendous" increases in air traffic delays in the United States has been caused by the FAA's slow approach to modernization.
Doug Helton, vice president of air traffic services and technology at the Aircraft Owners and Pilots Association, said "it makes sense to scale down the [ground-based] network on a gradual basis.
"But if you're going to shut off a third of the [Very High Frequency Omnidirectional Ranges], which ones do you shut off and what impact will that have on operations?" Helton said. "If a [navigation aid] has been around for 30 years and never upgraded, would it make sense to decommission that one first?"These are the "nitty gritty" issues that still must be ironed out, Helton said.-- Colleen O'Hara contributed to this article.