November 6, 2008
Contact: Tammy Jones
Phone: (202) 267-3476
In September 2008, the FAA passed a key milestone in its transition from a ground-based navigation infrastructure to an infrastructure based on satellites. The FAA has now published 1,333 Localizer Performance with Vertical guidance (LPV) approach procedures which are based on the Wide Area Augmentation System (WAAS), a space-based navigation system commissioned in 2003. This is significant as the number of approach procedures based on WAAS has now surpassed the number of approach procedures based on its ground-based predecessor, the Category-I Instrument Landing System (ILS). This is clearly a turning point for aviation and the way pilots navigate.
For the past 60 years, Category-I ILS has been used at airports throughout the National Airspace System (NAS) to guide aircraft to as low as 200 feet above the runway surface. WAAS, commissioned just five years ago, now provides this same capability, but at more runway ends. Today, WAAS LPVs can currently be found at 833 airports.
The number of WAAS LPVs will continue to grow. The FAA’s goal is to produce 500 new WAAS procedures each year until every qualified runway in the NAS has one. Additionally, WAAS has enabled a new approach capability which will be introduced in 2009.
The WAAS signal is provided from space so there is no need for the FAA to install and maintain navigation equipment at an airport, such as that needed for an ILS. Additionally, safety is improved as more aircraft are provided with vertically-guided approaches and improved flight planning options enabled by WAAS.
The Wide Area Augmentation System (WAAS) is a navigational system representing an enormous leap forward in air navigation. By virtue of its extensive coverage area, WAAS provides vertically-guided approach capability at thousands of airports and airstrips where this capability had previously not been affordable. It is a core element in transitioning to the satellite-based air traffic control system of the future.
WAAS is designed to improve the accuracy and ensure the integrity of positioning and timing information from Global Positioning System (GPS) satellites.
Although the WAAS was designed for aviation users, it supports a wide variety of non-aviation uses including agriculture, surveying, recreation, and surface transportation–just to name a few. The WAAS signal has been available for non safety-of-life applications since August 2000, and numerous manufacturers have developed WAAS-enabled GPS receivers for the consumer market. Today, there are millions of non-aviation WAAS-enabled GPS receivers in use.
WAAS was developed for the FAA by Raytheon Corporation.
WAAS uses a network of precisely-located ground reference stations that monitor GPS satellite signals. These stations are located throughout the continental U.S., Hawaii, Puerto Rico, Alaska, Canada and Mexico. The stations collect and process GPS information and send the information to WAAS master stations. The WAAS master stations develop a WAAS correction message that is sent to user receivers via navigation transponders on geostationary satellites. The WAAS message improves the accuracy, availability, and safety of GPS-derived position information. Using WAAS, GPS signal accuracy is improved from 20 meters to approximately 1.5 – 2 meters in both the horizontal and vertical dimensions. WAAS hardware consists of: 38 ground reference stations, 2 master stations, 2 geosynchronous satellites, 4 uplink stations, 2 operational control centers, and the WAAS terrestrial communications network.
Two of the FAA’s top goals are increased safety and greater capacity. WAAS provides for both, along with additional significant benefits:
WAAS is a pioneering technology. Currently, no other navigation technologies exist to meet FAA requirements and user needs for the expansion of vertically-guided landing capabilities at thousands of additional airports.
This page can be viewed online at: http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=6283