The UK Civil Aviation Authority's National Air Traffic Services (NATS) successfully conducted the first satellite-based augmentation approaches using the Northern European Satellite Test Bed (NESTBed), according to Flight International's sister publication Air Navigation International.
NESTBed, which has been developed by NATS to demonstrate the satellite-based augmentation system (SBAS) concept, is being used for operational evaluation in support of the European Geostationary Navigation Overlay System (EGNOS).
EGNOS is being developed by the European Commission, the European Space Agency and Eurocontrol to improve the accuracy, availability and integrity of global positioning system (GPS) signals for aeronautical, maritime and land-based users.
During the flight trials, which were conducted over a four-day period, the Defence Evaluation and Research Agency's (DERA) BAC 1-11 flying laboratory received signals from the NESTBed to make differential GPS approaches to DERA's Boscombe Down airfield. The programme is being conducted in conjunction with avionics manufacturer Racal, satellite system operator Inmarsat and service provider BT.
The flight demonstrations involved the use of the spare Inmarsat-3 satellite to relay augmented GPS signals to the aircraft via BT's navigation land earth station at Goonhilly in the south of England. A master control centre at London Gatwick Airport was connected through Racal's SkyFix network to remote integrity monitor stations at Aberdeen in Scotland, Rotterdam in the Netherlands, Cadiz in Spain, Ankara in Turkey and Bronnoysund in Norway. "This programme has been implemented very quickly. We've had a month to work with the system and we've conducted a week's worth of flights, so we have little data so far," says Bob Jeans, engineering manager at NATS. The flight demonstrations have produced encouraging results, according to NATS, with the use of the NESTBed consistently resulting in 2-3m lateral accuracy and below 6m vertical accuracy.
Representatives from airlines and aviation associations, including the Association of European Airlines (AEA), which is opposing the development of the EGNOS for aeronautical use, were on board the BAC 1-11 during the approach trials. A decision will be made shortly on future use of the NESTBed, says Jeans. Future activities could involve approach trials at alternative sites and interoperability work with the US Federal Aviation Administration.
Europe's EGNOS and the US equivalent, the Wide Area Augmentation System (WAAS), are intended to be compatible, with users equipped to use one system capable of using the other.
Source: Flight International
