FAA Gears Up For GPS Aircraft Precision Landing Approaches
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Written by Bradley S. Melara
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Monday, 09 March 2009 |
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By 1998, ground stations will be in place throughout North America to generate differential GPS corrections as part of the Wide Area Augmentation System (WAAS), a satellite system being built by the U.S. Federal Aviation Administration.
The ground stations generate corrections and uplink them to an Inmarsat satellite. The information is broadcast down on the GPS frequency to enable receivers designed to receive this information to improve the signal's accuracy, says Bruce Hensel, GPS product manager at the AlliedSignal Aerospace Commercial Avionics Systems division in Olathe, Kan.
Today the FAA does not allow GPS alone to be used as an aircraft navigational aid. Aircraft still must have VHF Omni-Range (VOR) radio beacon navigational equipment on board. When WAAS is implemented in 1998, GPS will be allowed as a primary means of navigation for Category I precision instrument landing approaches.
A Local Area Augmentation System (LAAS) will be set in place around 2000, Hensel says. This system uses airport-based ground reference stations to increase GPS signal accuracy. LAAS will enable pilots to make more-demanding Category II and III instrument landing approaches.
Non-precision instrument landing approaches require pilots to have the airport runway in sight while the pilots are no lower than 400 feet from the ground. Category I, II, and III approaches require the pilot to have the airport runway in sight at 200, 100, and 50 feet from the ground respectively.
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Last Updated ( Monday, 09 March 2009 )
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