From it's inception, the NAVSTAR GPS system has been operated by the Department of Defense. It was obvious; however, that NAVSTAR would have civilian uses as a precision navigation system. Civilian navigation services are operated by the Department of Transportation through the U.S. Coast Guard. DoD and DoT began joint planning in 1978 to reduce the need for different navigation systems for military and civil needs. After Soviet forces shot down Korean Airline Flight 007, President Ronald Reagan directed that the NAVSTAR GPS system operated by the DoD be made available by the DoT for international use.In December 1993, a joint DoD and DoT panel produced recommendations about how NAVSTAR should be managed to accomodate both military and civilian requirements. The report is available from the U.S. Coast Guard's NAVCEN web site and from the NAVTECH bookstore.
In early 1995, the National Research Council, under the direction of Congress, revisited the issue.
On August 3, the FAA issued a press release announcing the award of a $475 million dollar contract to Wilcox Electric for the development and installation of a Wide Area Augmentation System.
Integrity Issues
Accuracy Issues
Precision Landing
- Category I
- Category II
- Category III
Long Range Navigation
Wide Area Augmentation System (WAAS)
Wide Area Augmentation System is the name of an FAA sponsored program which will provide aircraft with a GPS derived navigation system capable of Category I instrument approaches. WAAS is similar in concept to John Chance & Associates' Omnistar system, supplying users with DGPS corrections and signal integrity messages via transmissions from geosyncronous satellites. When fully implemented in 2001, WAAS will greatly expand the number of airports capable of Cat I approaches. A contract has been let to Wilcox Electric for $475 million dollars to build WAAS. The contract was announced in a press release on August 3, 1995
Local Area Augmentation System (LAAS)
LAAS is a conventional DGPS system that takes over where WAAS leaves off. It is to be installed at the more heavily used airports where it will provide Cat I, II and III precision approach support. A local area augmentation system is much cheaper than a conventional instrument landing system and can therefore be installed at many more airports. At the time of this writing (10/95) no contracts have been let for implementing LAAS.
Future Air Navigation System (FANS)
The Future Air Navigation System (FANS) is part of an international movement to reduce or eliminate the need for aircraft to use airways, moving instead to a Free Flight concept. FANS consists of three parts: communications, navigation, and surveillance (CNS). Communications is usually provided via satellite but can also be accomplished via a datalink. The navigation portion of the system is provided by the Flight Management Computer (FMC) which uses GPS, inertial, air data, and other nav radios if available. Surveillance is done at an air traffic management (ATM) center where the aircraft are tracked. The benefit to this system is that aircraft can be tracked at all times even where there is no radar. It also allows reduced separation between aircraft. Today airplanes have to be separated by extreme amounts (~60 miles) when flying oceanic to avoid midairs due to navigation errors. With GPS to provide more accurate position, and satellite communications to report positions, separation can be reduced because the locations of the aircraft are known with great accuracy.Boeing has certified the FANS-1 system on the 747-400 airplane. Airbus is working on a similar system called FANS-A.
...visit the following web sites:
- The Intro to GPS Apps Applications Archive
- The Federal Radionavigation Plan at the USCG NAVCEN
- The Federal Aviation Administration
- MIT's Lincoln Laboratory
- MITRE Corporation's Center for Advanced Aviation System Development