Ground Based Augmentation System
The U.S. version of the Ground Based Augmentation System (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. GBAS is a ground-based augmentation to GPS that focuses its service on the airport area (approximately a 20-30 mile radius) for precision approach, departure procedures, and terminal area operations. It 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 flexible, curved approach paths. GBAS demonstrated accuracy is less than one meter in both the horizontal and vertical axis.
A Category I (CAT I) Non-Federal (non-Fed) system built by Honeywell International received System Design Approval (SDA) from the FAA on September 3, 2009. The Port Authority of New York/New Jersey (PANYNJ) has purchased and installed the first system at Newark Liberty International Airport. The system is expected to become operational later this year. The GBAS program is currently conducting a two-year Research and Development (R&D) and prototyping effort to reduce the technical risk and validate new requirements associated with meeting the GBAS approach service type D (GAST-D) service. The FAA’s GBAS office continues to work with industry and other service providers to facilitate development of International Civil Aviation Organization (ICAO) Standards and Recommended Practices (SARPs).Additionally, the FAA is working towards international GBAS implementation and interoperability by sharing technical expertise and approval processes with countries around the world. Airservices Australia, DECEA in Brazil, DFS in Germany, and AENA in Spain have been actively supporting the implementation of GBAS. All four countries have installed prototype GBAS systems and are involved in technical and operational evaluation activities. These nations are developing their own approval and certification processes but are still aiming to comply with FAA approval practices. Common understanding and practice of system approval, and the use of common test cases and tools will be valuable in the implementation of GBAS around the world.