Flight Test Results of Autocoupled Approaches Using GPS and Integrity Beacons

Clark Cohen, David Lawrence, Boris Pervan, H. Stewart Cobb, Andrew Barrows, J. David Powell, Bradford Parkinson, Victor Wullschleger and Steve Kalinowski

Abstract:	Flight tests augmenting differential GPS with Integrity Beacons (low-power pseudolite transmitters placed underneath the approach path) are demonstrating that GPS is capable of providing unprecedented levels of performance when used for Category III precision landing of aircraft. In a series of 49 autocoupled approaches in an FAA King Air at the FAA Technical Center, the Integrity Beacon Landing System (IBLS) performed flawlessly. In real time, the system provided on-board integrity monitoring and accuracy levels better than 1 ft as measured (and bounded) by the accuracy of the laser tracker used to monitor the flight performance independently. The Integrity Beacon is a low power ground transmitter broadcasting a GPS-like signal on Ll. As an aircraft flies overhead, it measures the carrier component of the signal from both the Integrity Beacons and the GPS satellites. Combined with measurements from the local area ground reference station at the airport, these onboard measurements are used to resolve the carrier wave cycle ambiguities quickly and reliably. The system provides centimeter-level position accuracy as well as an inherent level of onboard integrity better than one part in a billion. For the autocoupled approaches, IBLS position was provided to the autopilot in a form identical to the ILS output signal. The approaches were autocoupled to an altitude below 100 ft. The flight test results of the 49 approaches are presented and examined in terms of Navigation System Error (NSE), Flight Technical Error (FTE), and Total System Error (TSE).
Published in:	Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994) September 20 - 23, 1994 Salt Palace Convention Center Salt Lake City, UT
Pages:	1145 - 1153
Cite this article:	Cohen, Clark, Lawrence, David, Pervan, Boris, Cobb, H. Stewart, Barrows, Andrew, Powell, J. David, Parkinson, Bradford, Wullschleger, Victor, Kalinowski, Steve, "Flight Test Results of Autocoupled Approaches Using GPS and Integrity Beacons," Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994), Salt Lake City, UT, September 1994, pp. 1145-1153.
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