National Airspace System

The Federal Aviation Administration (FAA) relies on a ground-based navigation system that uses various types of equipment to assist pilots in navigating their assigned routes and to provide them with guidance for landing their aircraft safely in different types of weather. But this system is aging and limited in its geographic coverage. FAA is planning to transition from its ground-based system to a satellite-based system using radio signals generated by the Global Positioning System (GPS). In conducting its review, GAO examined studies and spoke with experts in aviation navigation and related technologies to obtain their views on the capability of FAA's new navigation system and alternatives to that system. From the studies it reviewed and experts it talked with, GAO found that the current GPS does not meet all of FAA's civilian aviation navigation requirements for accuracy, integrity, and availability.

GAO noted that: (1) according to studies GAO reviewed and the experts GAO contacted, the current GPS system does not meet all of FAA's civil aviation navigation requirements for accuracy, integrity, and availability; (2) even though DOD has made the GPS signal provided for civilian use more accurate and plans to make more improvements, GPS still will not fully meet FAA's requirements for navigation and landing; (3) this is because GPS does not provide the assurance that its signal will be available virtually all the time; (4) FAA's analysis concluded that the quantified benefits of its approach would outweigh the cost; (5) since completing this analysis, FAA has experienced delays and cost increases primarily because of difficulties in meeting its integrity requirement; (6) as a result, it is unclear whether quantified benefits will still outweigh cost; (7) at the present time, no other navigation technologies, including variations of ground-based and less robust satellite-based systems, are available to meet FAA's requirements and users' needs for precise landing guidance at more airports; (8) the Wide Area Augmentation System is designed to provide such guidance to improve safety and offer access to more airports; (9) however, this system is experiencing difficulties that cast doubt on whether it will perform as designed at a reasonable cost and be delivered on a reasonable schedule; and (10) moreover, experts in alternative navigation technologies, some of which compete with the Wide Area Augmentation System, told GAO that users may have overstated their need for precise landing guidance and that other navigation technologies could satisfy most of these needs.

Recommendations

Our recommendations from this work are listed below with a Contact for more information. Status will change from "In process" to "Open," "Closed - implemented," or "Closed - not implemented" based on our follow up work.

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