Chicago's O'Hare and Midway airports have become the latest to commit to satellite-based landing technology, with which the US FAA intends eventually to replace instrument landing systems (ILS).
Developed by US-Canadian team Honeywell/Pelorus to address the FAA's local area augmentation system (LAAS) requirement, the system is designed to improve the accuracy of satellite-based navigation for aircraft on final approach, by broadcasting corrections to the position information derived from Global Positioning System (GPS) satellites.
Chicago O'Hare last year joined a Honeywell-led consortium of manufacturers, US airlines and airports in a co-operative agreement with the FAA to develop LAAS technology. As part of the development effort, O'Hare has installed a prototype version of LAAS - known as the SLS-2000 - but because the technology does not have FAA certification, this system is presently limited to providing a supplemental navigation service under visual conditions.
Midway Airport has not had even this preliminary technology installed. But under the new agreement, both airports will be equipped with the updated LAAS version - designated SLS-3000 - which is being developed to meet new FAA general-use criteria.
LAAS is intended to provide Chicago with several advantages over its present ILS equipment. While a single ILS can only serve one runway end, a LAAS installation can potentially cover multiple runways.
ILS radio transmitters are also restricted to providing a straight-line guidance path. By broadcasting accurate GPS data over the entire local airspace, LAAS frees aircraft from the need to follow a fixed radio transmission.
Pelorus president and CEO Michael Beamish tells ATI: "We're looking at certification in early 2002. In the meantime, the authorities will be working on developing new approach paths, such as curved approaches, which the system can provide."
The new technology will give greater flexibility to congested airports such as O'Hare, enabling airspace planners to design more efficient, and more environmentally-acceptable, flight paths.