ABSTRACT
The Federal Aviation Administration (FAA) has initiated plans to transition from its present ground-based navigation and landing system to a satellite-based system using signals provided by the Department of Defense's Global Positioning System (GPS). However, GPS alone will not meet all aviation positioning requirements. To meet the National Airspace System (NAS) requirements, the FAA has proposed two augmentations to GPS： a Wide Area Augmentation System (WAAS) and a Local Area Augmentation System (LAAS). There have been expressions of concern regarding the robustness of this plan and whether the risks to dependence upon GPS have been adequately addressed. In response to this concern, the FAA, with co-sponsorship from the Air Transport Association (ATA) and the Aircraft Owners and Pilots
Association(AOPA), issued a request for an impartial study. the Johns Hopkins University Applied Physics Laboratory (JHU/APL)was selected to conduct that study, which is the subject of this report.
The repot quantifies the ability of GPS, GPS/WAAS, and GPS/LAAS to satisfy Required Navigation Performance (RNP) as expressed by accuracy, integrity, continuity, and availability requirements. Additional navigation options that mitigate the identified risks were also evaluated. In particular, these options included potential improvements to the GPS Standard Positioning
Service (SPS) and additional capabilities onboard the aircraft such as integration of additional sensors and application of GPS anti-jam technologies.
KEYWORDS： National Airspace System
Global Positioning system
Navigation
