-----Original Message-----

Sent: Tuesday, 2 October 2001 1:31 AM

To: bluecoat

Subject: [bluecoat] GPS precision approaches

Thought that this topic may be a worthwhile distraction!:

Raytheon and Air Force Demonstrate Civil-Military Interoperability for GPS-Based Precision Auto-Landing System.

MARLBOROUGH, Mass., Oct. 1 /PRNewswire/ --

A government-industry team accomplished the first precision approach by a civil aircraft using a military Global Positioning System (GPS) landing system on Aug. 25 at Holloman AFB, N.M., Raytheon Company (NYSE: RTN) announced today. A FedEx Express 727-200 Aircraft equipped with a Rockwell-Collins GNLU-930 Multi-Mode Receiver landed using a Raytheon-developed military ground station. Raytheon designed and developed the differential GPS ground station under an Air Force contract for the Joint Precision Approach and Landings System (JPALS) program. The JPALS system is being developed to meet the Defense Department's need for an anti-jam, secure, all weather Category II/III aircraft landing system that will be fully interoperable with planned civil systems utilizing the same technology. Raytheon and the U.S. Air Force have been conducting extensive flight testing for JPALS at Holloman over the last three months. The FedEx Express 727-200 aircraft at Holloman successfully conducted a total of sixteen Category I approaches. After completing a number of pilot flown approaches for reference the aircraft conducted six full autolands using the JPALS ground station. "The consistency of the approaches allowed us to proceed to actual autolandings with very little delay," said Steve Kuhar, Senior Technical Advisor Flight Department for FedEx Express. The aircraft was guided by differential GPS corrections, integrity information, and precision approach path points transmitted from the Raytheon developed JPALS ground station. Although the approaches were restricted to Category I, accuracies sufficient to meet Cat II/III requirements were observed. Raytheon is the world leader in designing and building satellite-based navigation and landing solutions for civil and military applications. In addition to developing JPALS for the Department of Defense, Raytheon is also developing both the Local Area Augmentation System (LAAS) and the Wide Area Augmentation System (WAAS) for the Federal Aviation Administration. The JPALS and LAAS will provide an interoperable landing capability for military and civil applications. "Raytheon is committed to developing and deploying satellite based navigation and landing systems for the military and the flying public," said Bob Eckel, Raytheon vice president for Air Traffic Management. "We understand the importance of this technology and are proud to be a part of the success achieved this summer during JPALS testing at Holloman." With headquarters in Lexington, Mass., Raytheon Company is a global technology leader in defense, government and commercial electronics, and business and special mission aircraft.

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-----Original Message-----
From: bluecoat
Sent: Thursday, 4 October 2001 4:54 AM
To: bluecoat
Subject: [bluecoat] Re:
Hope for secure GPS?

FWIW, a number of years ago, I went to ABQ and flew a Gulfstream equipped with the JPALS system. As it was explained to me, the guts of the system, at that time, was taken from a Pershing missle. The missle had a "picture" of the target and it had a fast scan radar. It knew certain points from its navigation system. It then overlaid the picture with what it saw and kept modifying its flight until the two pictures were the same. The Pershing did all this at about Mach Much... <G>

The idea of the JPALS was to take a runway anywhere, get the nav points, get a picture (via satellite or other sources) and data link the info to an airplane. It could be encrypted, obviously. This way Bongo 51 could be dispatched to a runway in the middle of the night, shoot a precision approach to a runway with NO navaids. This would allow the planners and fliers to go into a runway, disperse personnel, leave immediately and then rendezvous again at another airfield, again with no ground nav aids. As the system was completely contained within the airplane, there was nothing to alert anyone on the ground as to the arrival or departure.

I thought of JPALS when the forces went into Bosnia and had to have forces survey the field, install the system, fly and certify it and then publish it.. JPALS avoids all this and after flying about 10 approaches, mixing the ILS with JPALS info, it was hard to define which was which.



Automatic Landing of a 737 using
GNSS Integrity Beacons


Clark E. Cohen, H. Stewart Cobb, David G. Lawrence, Boris S. Pervan,
Andrew K. Barrows, Michael L. O'Connor, Konstantin Gromov,
Gabriel H. Elkiam, Jock R. I. Christie
J. David Powell, and Bradford W. Parkinson

Department of Aeronautics and Astronautics
Stanford University

Gerald J. Aubrey, Willaim Loewe
United Airlines

Douglas Ormiston
Boeing Commercial Airplane Group

B. David McNally, David N. Kaufmann
NASA Ames Research Center

Victor Wullschleger
Federal Aviation Administration Technical Center

Ray Swider
Federal Aviation Administration

Presented at ISPA, Braunschweig Germany, February 1995



Differential GNSS and miniature, low-cost Integrity Beacon pseudolites were used to carry out 110 successful automatic landings of a United Boeing 737-300 aircraft. The goal was to demonstrate Required Navigation Performance (RNP) - including accuracy and integrity - for Category III Precision Landing using GNSS. These autopilot-in-the-loop flight tests using GNSS Integrity Beacons (low-power, ground-based marker beacon pseudolites placed under the approach path) furnish evidence that GNSS can provide the full performance necessary to meet the stringent specifications of Category III.

It has been demonstrated that Integrity Beacons can provide consistent accuracies on the order of a few centimeters. But perhaps even more important, this centimeter-level accuracy coupled with the built-in geometrical reduncancy provided by Integrity Beacon ranging provides an exceptional level of intrinsic system integrity. This integrity is calculated to be easily better than the required one part in a billion probablility of missed detection. Passenger safety is improved significantly because this level of integrity is achieved independently from ground-based monitors through Receiver Autonomous Integrity Monitoring (RAIM).

For the flight test, the GPS receiver and single-channel navigation computer calculated precise positions and calculated glide path deviations. An analog interface provided ILS localizer and glideslope signals to the autopilot. The 737 was equipped with a dual-channel flight control system whch was previously certified for Category IIIA landings. The autolands were performed through touchdown without rollout guidance. The series of 110 automatic landings were carried out at NASA's Crows Landing facility in California over a four-day period during the week of October 10, 1994. A laser tracker was used as an independent means for characterizing flight performance. The feasibility demonstration was sponsored by the FAA.

GNSS = Global Navigation Satellite Systems


Return to Publications List of the Stanford University GPS Lab

Clark E. Cohen clark@relgyo.stanford.com