Ramon Lopez/WASHINGTON DC
It will take at least 10 years for the USA to complete its transition from ground-based navigation aids to the satellite-based global positioning system (GPS) for "sole means" navigation, according to US aviation officials.
Meanwhile, Loran-C, which is operated by the US Coast Guard for en route navigation and which was to have been shut down by 31 December 2000, will remain operational for at least eight more years.
US Federal Aviation Administrator Jane Garvey told the International Civil Aviation Organisation (ICAO) Council this month that the transition to the global navigation satellite system (GNSS) would be gradual.
"As we transition to GPS," she said, "prudent operating practices may require that such ground-based navigation aids as the VHF omnidirectional radio range [VOR] system, distance measuring equipment [DME] and the instrument landing system [ILS] be kept until the civil aviation community gains confidence that GPS is capable of providing sole service.
"Within the US National Airspace System, we anticipate that it will take at least a decade to complete the transition. Each ICAO member state will need to review its own operational requirements to determine whether to use augmented GPS, or other elements of the GNSS, as its sole service."
The FAA is developing the wide area augmentation system (WAAS) to support all phases of flight up to Category I precision approaches. The local area augmentation system (LAAS) will allow Category II and III operations.
WAAS software problems have caused its Phase 1 commissioning to slip beyond July 1999. The current plan is to have 50 WAAS approaches certificated for operational use in the USA by September 2000. The US aviation agency plans to commission the first LAAS three years later.
The so-called L1 frequency of GPS has been available for civil use through the less-precise standard positioning service (SPS). The L2 (1227.6MHz) frequency was added a year ago to provide a second signal for civil applications. In January, a third signal (1176.45 MHz) was added to improve GPS services for civil users, but this will not be available before 2013-5.
Source: Flight International
