Enhanced GPS service (WAAS) now in use by the U.S. commercial aviation industry and activated 13 months prior to the terrorist attacks of September 11, 2001, provided virtual aerial navigation corridors only 243 wide and a 95% confidence that an aircraft's true position will fall within such a corridor . Such corridors can be navigated entirely by autopilot and flight management systems scheduled in 1996 and 1998 to be contained by United and American airlines Boeing 757 and 767 aircraft like those used during the terrorist attacks of September 11, 2001.
WAAS also supports required navigation performance (RNP) operations, says Raytheon, providing a precision navigation capability down to RNP 0.02 (an accuracy of 0.02nm).
RNP is a required navigation performance level described by the specification of a numeric value indicating the required navigation accuracy for a specific operation, typically specified laterally in nautical miles - e.g., RNP 1 is a Required Navigation Performance of ± 1 nautical mile (95% Probability).
1 nautical mile = 6,076 feet
RNP 0.02 = RNP (0.02 nautical mile radius) x 2 = RNP (121.5 foot radius) x 2 = a 243 foot wide corridor.
AMENDED VERSION: Wide Area Augmentation System Signal Now Available
August 24, 2000
WASHINGTON, DC — After a successful 21-day stability test of the Wide Area Augmentation System (WAAS) signal in space, the U.S. Department of Transportation's Federal Aviation Administration (FAA) declared that it is now available.
According to Raytheon’s director-satellite navigation systems, the newly activated WAAS signal was used by rescuers at New York City's Ground Zero site following September 11, 2001 in order to precisely survey the site:
And, at the World Trade Center, rescue teams used WAAS to survey the site during the recovery program.
By 1996 and 1998, United and American airlines Boeing 757 and 767 aircraft, like those used during the terrorist attacks of September 11, 2001, were scheduled to contain flight management systems and signal receivers capable of utilizing the new GPS service.
HONEYWELL ANNOUNCES ORDERS FOR NEW-GENERATION "PEGASUS" FLIGHT MANAGEMENT SYSTEM
FARNBOROUGH, ENGLAND, SEPT. 7, 1998 - The Honeywell "Pegasus" flight management system earned its first FAA certifications March on the Boeing 757, 767 and MD-90 aircraft types ... Airlines get FANS-1/FANS-A capability ... FANS-1 ... allows operators to obtain more economical routings and to utilize satellite navigation.
Key elements of Future Air Navigation System (FANS): RNP – Required Navigation Performance
Using WAAS, a satellite-based system ... has allowed the FAA to move toward a performance-based NAS, exploiting the concept of “required navigation performance,” or RNP.
Rockwell's Collins Landing System Picked for Both Airbus and Boeing Planes
CEDAR RAPIDS, Iowa, Sept. 6, 1996 /PRNewswire/ -- Rockwell's Collins Commercial Avionics, based in Cedar Rapids, has made major announcements of the selection of its Multi-Mode Receiver (MMR) landing system by two of the world's leading aircraft manufacturers, Airbus and Boeing ... Subsequent certifications are planned for Boeing's ... 757 and 767 ... The Multi-Mode Receiver ... expands capabilities required by the air transport industry as the Global Navigation Satellite System (GNSS) is phased into operation.
GNSS-1 is the first generation system and is the combination of existing satellite navigation systems ... In the United States, the satellite based component is the Wide Area Augmentation System (WAAS).
October 1999:
Digital flight control systems on Boeing airplanes ... automatically fly the airplanes on pre-selected routes, headings, speed or altitude maneuvers.
An Air China Boeing 757, generally containing common flight systems with the Boeing 767, reportedly navigated a complex flight segment exclusively under GPS guided autopilot control via RNP operation:
Guided entirely by autopilot, an Air China Boeing 757 jet last month snaked along a narrow river valley between towering Himalayan peaks ... Pilots and passengers looked out to mountains left and right as the airplane automatically followed the twists of the valley, descending on a precisely plotted highway in the sky toward a runway still out of sight ... Using global-positioning satellites and on-board instruments, Naverus' navigation technology pinpoints the location of a fast-moving jet to within yards ... "You're watching the whole thing unfold. The airplane is turning, going where it's supposed to go ... it's all automatic."
The WAAS signal also made possible under autopilot control, the 370 degree decending right turn from an altitude of 7,000 feet, performed by American Airlines flight 77 prior to its reported impact with the Pentagon building in Arlington, VA on September 11, 2001.
Stanford University, 1998:
The Wide Area Augmentation System (WAAS) ... allows pilots to fly ... approaches that cannot necessarily be flown with current instrumentation ... Complex curved approaches, including approaches turning to a short (less than one mile) final ... Pathways were constructed from ... climbing, or descending constant radius arcs ... Autopilots could use WAAS position and velocity to fly curved trajectories.
In October of 2001, Cubic Defense Systems applied for a U.S. patent for a system that utilizes GPS guided aircraft autopilot systems to implement a programmed or remotely transmitted flight plan, that overrides pilot control of an aircraft and navigates it to a given destination.
Responsive to the override input, the manager deactivates on-board control of selected aircraft flight systems and the autopilot system, and directs the autopilot to fly the aircraft ... In planning the flight routing ... the manager may utilize ... GPS direct routing.
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