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Congressional Staff

This page is an overview of the FAA Satellite Navigation Program and has been tailored for use by congressional staff. As such, it contains a focused subset of data available on the FAA following programs:


What is WAAS?

The Wide Area Augmentation System (WAAS), commissioned in 2003, provides very precise navigation service to guide aircraft on departures, en-route and arrivals, including horizontal and vertical accuracy on approaches as low as 200 feet above all qualifying runways in the Continental United States (CONUS) and a large portion of Alaska and Canada. The system currently consists of 38 monitoring stations installed in the United States (US), Canada, and Mexico, 3 master stations, 6 ground earth stations serving 3 geostationary satellites, and 2 operations control stations.

The WAAS signal can also be used for many non-aviation applications, as well. Many users have utilized the system's increased accuracy for applications such as hiking, boating, and agriculture.

Wide Area Augmentation System map noting locations of wide-area reference stations, wide-area master stations, and ground earth stations
                                       Wide Area Augmentation System (WAAS)

Read a detailed description of How WAAS Works.

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What is GBAS?

The Ground Based Augmentation System (GBAS) is an augmentation to GPS that focuses its service on the airport area (approximately a 20-30 mile radius). GBAS broadcasts its correction message via a very high frequency (VHF) radio data link from a ground-based transmitter. GBAS will yield the extremely high accuracy, availability, and integrity necessary for Category I, II, and III precision approaches, and will provide the ability for more flexible, curved approach paths. GBAS demonstrated accuracy is less than 1 meter in both the horizontal and vertical axis.

GBAS Architecture
                                       Ground Based Augmentation System (GBAS)

The U.S. version of the GBAS has traditionally been referred to as the Local Area Augmentation System (LAAS). The worldwide community has adopted GBAS as the official term for this type of navigation system. To coincide with international terminology, the FAA is also adopting the term GBAS to be consistent with the international community.

Read a detailed description of How GBAS Works.

The Ground Based Augmentation System (GBAS) program is managed by the FAA Aviation NextGen and Operations Planning Service Unit (AJP-652) at the FAA William J. Hughes Technical Center. More information can be found at

SatNav Newsletter

The SatNav News, the Federal Aviation Administration's satellite navigation newsletter, provides the latest information on FAA satellite navigation initiatives that support the aviation community and the general public.

Please be sure to check out the latest version of the SatNav News available Online.

SatNav News
                                                    Click above for SatNav news

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