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WAAS User Segment
|Title||WAAS User Segment|
|Year of Publication||2011|
The Wide Area Augmentation System (WAAS) is the United States Satellite Based Augmentation System. The programme, started in 1992, is being carried out by the Federal Aviation Agency (FAA) and is specially developed for the civil aviation community. The system, which was declared operational in late 2003, currently supports thousands of aircraft instrument approaches in more than one thousand airports in USA and Canada. WAAS service area includes CONUS, Alaska, Canada and Mexico. The WAAS programme is continuously in evolution; three development phases have been already covered, and there are on-going plans to improve the capability of the system in parallel with the evolution of the SBAS standards towards a dual-frequency augmentation service.
WAAS User Segment
The WAAS user segment consists in the GNSS receivers that combine GPS information with the SBAS signal-in-space broadcast by the WAAS GEO satellites. As such, the user segment is not under the control of the WAAS service provider, FAA, and it is driven by the GNSS application market. Although the prime target of WAAS is the civil aviation user community, most of GPS receivers nowadays can be configured to receive and process WAAS signal-in-space (SIS), so they can benefit from the enhanced accuracy and/or integrity offered by WAAS.
WAAS users include any aircraft with approved SBAS avionics using a SBAS-enabled GPS receiver. The WAAS user equipment shall be compliant (certified) against several standards, i.e. RTCA MOPS DO 229 (see article SBAS Standards). The civil aviation certified equipment is in the highest rank with respect its cost. There exist a large number of certified receivers manufacturers worldwide, including:
Aircraft Supplemental Type Certificates (STC) have been issued by the FAA for an important number of aircraft models equipping WAAS-compliant avionics, including, among others, aircraft from Boeing, Bombardier, Cessna, Embraer, Falcon, Hawker... Other certificates are in progress including airplanes from other companies such as Airbus or Lockheed Martin.
The non-safety-of-life devices comprise low cost, general purpose GPS equipment that uses the WAAS signal-in-space (SIS) to provide the user with an enhanced accuracy performance in comparison with the one provided by a standalone GPS device. In comparison with the certification requirements of the safety-of-life user equipment, the general-purpose equipment is not necessarily compliant with the RTCA MOPS DO 229 processing rules, but might only make use of the processing algorithms that render the accuracy corrections provided by the SBAS SIS.
- ^ Navigation Services - History - Satellite Navigation, FAA.
- ^ Navigation Services - Wide Area Augmentation System (WAAS), FAA.
- ^ Wide Area Differential GPS (WADGPS), Stanford University
- ^ a b GNSS - GPS/WAAS Approaches, Federal Aviation Agency (FAA).
- ^ WAAS Service Expanded into Canada and Mexico, September 28, 2007, Federal Aviation Agency (FAA).
- ^ SatNav News, Vol. 33, March 2008, Federal Aviation Agency (FAA).
- ^ List of available SBAS receivers, ESA, March 2006.
- ^ a b c WAAS Program Update, 2011, FAA