Boeing/Industry Team Evaluates Automatic Landing Systems

SEATTLE, Aug. 2, 1995 -- Boeing is leading an industry team to validate the use of the global positioning system (GPS) for Category I, II and III automatic landings, which classify the degrees of cloud, ceiling and runway visibility.

GPS is a U.S. government-owned constellation of 24 satellites. The system is being offered to the world's air, sea and ground transportation users with no fees while navigation technologies are being developed.

Flight testing of four global landing system (GLS) concepts is currently under way at NASA's Wallops Island Air Field in Virginia, following pre-trials out of the Boeing Glasgow, Mont., airfield.

Trial objectives are to demonstrate accuracy, high integrity, availability of satellite signal and continuity of function. "The GPS landing system development is a long- term program," says Boeing GLS Program Manager Dean Miller, "but we believe it is a value-added technology that can potentially save airlines billions of dollars. GPS represents a great opportunity to enhance aviation capacity and efficiency."

Boeing team members for the GLS program include NASA Langley, Honeywell/Pelorus Navigation Systems, Rockwell- Collins/Daimler-Benz Aerospace, Litton/Wilcox and Interstate Electronics/Airport Systems International. NASA has donated the use of its 757, airfield and laser tracker while Boeing is providing the aircraft integration and operations.

All four GLS systems are installed and are being tested simultaneously on the 757, although only one is coupled to the autopilot for each approach. The others are linked to data recorders. This will provide the manufacturers with experience in interfacing GLS with an existing autopilot, a ground rule for the trials.

The flight test plan is to conduct 200 to 250 landings with 50 to 75 for each system. In later bench tests, using a satellite simulator, the performance of each system will be evaluated under extreme conditions, including multipath, atmospheric conditions and selective satellite availability effects.

"The program is much more than just a trial," says Miller. "We will be testing systems, developing simulations and defining certification requirements. The flight tests are providing the test data needed for the simulation phase which will run through the end of next year. This flight test data, along with bench testing will provide the data needed to validate the computer simulation." can."