Federal Aviation Administration Twentieth Edition
18.16.1.8 Entering, flying, and exiting holding patterns, particularly on overlay approaches with a second waypoint in the holding pattern.
18.16.1.9 Programming and flying a “route” from a holding pattern.
18.16.1.10 Programming and flying an approach with radar vectors to the intermediate segment.
18.16.1.11 Indication of the actions required for RAIM failure both before and after the FAWP.
18.16.1.12
Programming a radial and distance from a VOR (often used in departure instructions).
19.
Wide Area Augmentation System (WAAS)
19.1 General
19.1.1 The FAA developed the Wide Area Aug-mentation System (WAAS) to improve the accuracy, integrity and availability of GPS signals. WAAS will allow GPS to be used, as the aviation navigation system, from takeoff through Category I precision approach when it is complete. WAAS is a critical component of the FAA’s strategic objective for a seamless satellite navigation system for civil aviation, improving capacity and safety.
19.1.2 The International Civil Aviation Organiza-tion (ICAO) has defined Standards and Recom-mended Practices (SARPs) for satellite.based augmentation systems (SBAS) such as WAAS. Japan and Europe are building similar systems that are planned to be interoperable with WAAS: EGNOS, the European Geostationary Navigation Overlay System, and MSAS, the Japan Multifunctional Transport Satellite (MTSAT) Satellite.based Aug-mentation System. The merging of these systems will create a worldwide seamless navigation capability similar to GPS but with greater accuracy, availability and integrity.
19.1.3 Unlike traditional ground.based navigation aids, WAAS will cover a more extensive service area. Precisely surveyed wide.area ground reference stations (WRS) are linked to form the U.S. WAAS network. Signals from the GPS satellites are monitored by these WRSs to determine satellite clock and ephemeris corrections and to model the propagation effects of the ionosphere. Each station in the network relays the data to a wide.area master station (WMS) where the correction information is computed. A correction message is prepared and uplinked to a geostationary satellite (GEO) via a ground uplink station (GUS). The message is then broadcast on the same frequency as GPS (L1, 1575.42 MHz) to WAAS receivers within the broadcast coverage area of the WAAS GEO.
19.1.4 In addition to providing the correction signal, the WAAS GEO provides an additional pseudorange measurement to the aircraft receiver, improving the availability of GPS by providing, in effect, an additional GPS satellite in view. The integrity of GPS is improved through real.time monitoring, and the accuracy is improved by providing differential corrections to reduce errors. The performance improvement is sufficient to enable approach procedures with GPS/WAAS glide paths (vertical guidance).
19.1.5 The FAA has completed installation of 25 WRSs, 2 WMSs, 4 GUSs, and the required terrestrial communications to support the WAAS network. Prior to the commissioning of the WAAS for public use, the FAA has been conducting a series of test and validation activities. Enhancements to the initial phase of WAAS will include additional master and reference stations, communication satellites, and transmission frequencies as needed.
19.1.6 GNSS navigation, including GPS and WAAS, is referenced to the WGS.84 coordinate system. It should only be used where the Aeronautical Information Publications (including electronic data and aeronautical charts) conform to WGS.84 or equivalent. Other countries civil aviation authorities may impose additional limitations on the use of their SBAS systems.
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