GPS STATUS AND VISION
by Thomas E. McSweeny
As we approach the close of the 20th century, the groundwork we are now laying will lead to the future air traffic management system for the 21st Century. Look back 95 years to the Wright Brothers first flight; think about the progress that has been made from that event to today. In one hundred years, I am confident that the systems we are developing now will be the backbone and the framework for the systems of the 22nd Century. That is why I believe that satellite technology is the most important technological breakthrough in civil aviation navigation since radar was introduced over 50 years ago. I'd like to share with you a little about what the FAA and others are doing in support of its commitment to Global Navigation Satellite System (GNSS).
I'd also like to discuss some of the challenges that we face, as well as talk about a few new air traffic management initiatives that we have underway. GPS Satellite technology is already in use in the United States and elsewhere as a navigation aid for en route, oceanic, and remote airspace, and also for non-precision approaches. The U.S. Global Positioning System (GPS) provides this service as part of the Global Navigation Satellite System (GNSS), which also includes the Russian GLONASS system (a complementary, not competing, system). GNSS, with developments underway today, will provide even greater safety benefits by making precision approaches possible at thousands of airports worldwide, where no such capability exists today.
These benefits will be especially significant in many developing countries where the ground-based navigation aids needed to support safe civil aviation operations are limited or even non-existent. Additionally, we believe GNSS will bring about crucial capacity enhancements that will help meet the growing worldwide demand for air transport services well into the next century. Ensuring the use of satellite technology by aviation is a high priority for the FAA, and, as aviation is inherently an international endeavor, we are committed to working cooperatively with our international partners to develop a seamless global navigation satellite system.
The use of GPS in en route, oceanic, and remote airspace, as well as for non-precision approaches, has already improved safety in U.S. airspace. The introduction of new, straight-in approach procedures has reduced the need for procedure turns and circling approaches. GPS provides a very reliable and accurate navigation system that dramatically improves safety over an NDB approach or a VOR approach when the VOR is not collocated with the runway. GPS has also improved safety for en route navigation, providing service at low altitudes where no navigation service previously existed due to line-of-sight limitations associated with ground-based navaids. Oceanic operations have been made safer by replacing Omega navigation with GPS. I encourage all Member States to review the ICAO Circular on early implementation of GNSS and take advantage of the safety improvements that are available today.
At the last ICAO General Assembly in September, FAA Administrator Jane Garvey reiterated the FAA's commitment to pursuing GPS and its augmentations, and she invited, once again, any Member State desiring to use GPS for its own operations to do so without charge.
Today's GPS system, however, does not meet the high standards of accuracy, integrity, and availability required for precision approaches and landings. As a result, the FAA is developing two augmentation systems to improve the capabilities of GPS.
The Wide Area Augmentation System (WAAS) is one of the cornerstones of the modernization of the U.S. air traffic management system. Combined with GPS, it will provide users with capabilities from en route navigation through Category I precision approaches. The WAAS network of geostationary satellites and 25 ground stations, which have already been installed, will augment the basic GPS signal to provide the accuracy, integrity, and availability that is crucial to civil aviation operations. This year alone, the FAA is spending over $85M on this program to deliver this capability.
As many of you are aware, the Administrator announced in January that implementation of the WAAS program would be delayed approximately 14 months. The delay will allow more time to complete development of a critical software safety package that monitors, corrects, and verifies the performance of the WAAS. The FAA will not commission Phase I of WAAS until we are satisfied that the system is safe and all problems have been resolved. We believe this is a smart, prudent approach to developing a technology that is key to the operational safety and efficiency of our National Airspace System, as well as of the global system.
The second GPS augmentation system, the Local Area Augmentation System (LAAS), is ground-based and will be used to support Category I, II, and III approaches and landings.
LAAS equipment, located on or near an airport, will augment GPS within 30 miles of the airport. It could also be used for other terminal activities including high-speed turn-offs and surface operations, missed approaches, departures, and vertical take-offs.
At this time, the LAAS program is in the process of establishing government and industry partnerships to develop the LAAS to support Category I/II/III precision approach and landing operations.
Environmental benefits may arise from GNSS as well. By facilitating more precise, targeted approaches, use of GNSS could lead to less fuel consumption and reduced aircraft noise over noise sensitive areas.
Further evidence of our commitment to advancing GNSS can be found in Vice President Gore's announcement in January of a $400 million initiative to modernize GPS. The new funding will allow the addition of two new civil signals to future GPS satellites, which will significantly enhance the service provided to civil, commercial, and scientific users. In response to the ICAO recommendation, one signal will be in the aeronautical safety-of-life band currently used by DME and ACAS.
One challenge that we all face is the "sole means" issue. Last summer, to make sure that the path we were following was smart and sensible, we supported an aviation industry initiative for an independent study. This study was carried out by the highly respected Johns Hopkins University Applied Physics Laboratory of Maryland. Their charge was to look at the risks associated with GPS and determine if augmented GPS could be the only navigation system in an aircraft (i.e., "sole-means") and the only navigation service that the FAA provides (i.e., "sole-service").
This study was co-sponsored by the Aircraft Owners and Pilots Association (AOPA) which represents general aviation pilots and the Air Transport Association (ATA) which represents leading airlines. Its member carriers transport over 95% of all passenger and cargo traffic in the United States.
At the end of January, we received the results of the six-month risk assessment. The report affirmed that augmented GPS can "satisfy the performance requirements to be the only navigation system installed in an aircraft and the only service provided by the FAA for operations anywhere in the National Airspace System."
Risks to GPS from natural, man-made, and hostile radio interference were all judged to be manageable. "Technologies are emerging that can greatly reduce vulnerability to GPS signal jamming," the study said. We continue to evaluate the effects of jamming and the interference issues in cooperation with the international community.
We are encouraged by the Johns Hopkins risk assessment; the FAA remains committed to delivering sole-means GNSS. We are developing an action plan to address all of the issues and recommendations that have been raised by the study.
Augmentation systems like WAAS and LAAS will enable GPS to be used as a "sole means" system of navigation. For purposes of clarity, the FAA uses the term "sole means" as defined in ICAO Circular 267, which refers to the navigation equipment on an aircraft and signifies that GNSS equipment will be the only navigation equipment required on board an aircraft to support a particular operation or phase of flight. GPS, with proper augmentation, is designed to be used as a "sole-means" system and the U.S. is committed to achieving this goal.
This differs from the concept of "sole service," which refers to the provision of GNSS as the only radio-navigation service in a region or for an operation. In most U.S. airspace, this will involve the decommissioning of existing ground-based navigation services such as VOR and ILS.
The pace and extent of user transition to augmented GPS as "sole-service" navigation depends on numerous factors, all centering on system performance and user acceptance. These factors include benefits from GNSS, avionics costs, satellite availability, and the reliability of systems designed to overcome the risks associated with jamming and unintentional interference from the atmosphere and other sources.
The decommissioning schedule is predominantly a transition issue: We must decide how long users will have to equip with new services before older services are withdrawn, and we must decide which ground-based services will be retained the longest. This transition cannot happen overnight, and will be driven by operational experience and user acceptance. While the FAA plans to decommission the majority of ground-based navigation aids--over time and with much thought about safety as our paramount concern --GNSS may not become the "sole-service" means of navigation in some congested airspace-at least in the near future. This does not diminish our commitment to making GNSS a "sole-means" system, through augmentation by WAAS and LAAS. To validate this commitment, we are conducting a refined investment analysis to determine the most cost-effective combination of satellite-based navigation services.
Despite these challenges, the FAA is committed to the implementation of WAAS and is heartened by the support of U.S. system users. Carol Hallett, President of the Air Transport Association, has said that the Johns Hopkins study "clearly shows that, with the proper investment and augmentation, GPS will become the navigation system for the 21st century."
The U.S. General Aviation community is solidly behind GPS. Phil Boyer, President of the Aircraft Owners and Pilots Association (AOPA) stated recently, "This is cutting-edge technology. We're willing to accept some delay to ensure that GPS/WAAS is completely proven and reliable." AOPA represents over 340,000 members who own 75% of the 190,000 non-airline aircraft in the U.S.
Our domestic efforts to deploy systems to take advantage of GPS are not undertaken in a vacuum. Cooperation with our international partners in applying satellite technologies to aviation is important, both globally and nationally, in order for all of us to fully enjoy the benefits of GNSS. To ensure that WAAS and LAAS are interoperable with other systems, we have been working closely with ICAO, through the GNSS Panel, to develop standards and recommended practices (SARP) relative to satellite navigation. We look forward to the GNSS Panel approving the SARP this April. We have also been cooperating with the other providers of space-based augmentation systems (SBAS) on system implementation and have been working directly with other nations on GPS implementation and demonstration of augmented GPS performance. We plan to continue these efforts to ensure that we implement a seamless, global area navigation system.
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