FAA Passes Milestone, Users Want More

At a time when air taxi and general aviation operators have more WAAS approaches as number one on their wish lists, the Federal Aviation Administration said it passed a key milestone in its ground to satellite transition, having published 1,333 Localizer Performance with Vertical guidance (LPV) approach procedures which are based on the Wide Area Augmentation System (WAAS). The five year-old satellite-based system surpassed the number of approach procedures based on its ground-based predecessor, the Category-I Instrument Landing System (ILS), said FAA, calling it a turning point for aviation and the way pilots navigate.
Still, air taxi operators speaking before the NBAA convention indicated that more needs to be done as the lack of such navaids impacts their performance and significantly increases the fees clients must pay with weather delays. Related Story 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.
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.
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.