Europeans catching up with WAAS, GPS

 - January 14, 2008, 11:15 AM

While EGNOS, SBAS, GBAS and Galileo may be unfamiliar to most North American aviators, they are key elements in Europe’s determined move to a satellite air traffic control environment. Addressing the FAA’s satellite operations implementation team meeting in December, Eurocontrol officials reported on progress toward their vision of
a satnav future. But it’s more than just a vision–these are real programs currently under way, with at least one moving ahead of the U.S.

EGNOS (European geostationary navigation overlay system) is equivalent to the FAA’s WAAS, which will transmit GPS integrity alerts and accuracy corrections. EGNOS will overlap WAAS in the mid-Atlantic and extend east to central Asia, where it will overlap with Japan’s WAAS-like multi-transport satellite augmentation system (MSAS), which will overlap with WAAS in the mid-Pacific to complete worldwide coverage. EGNOS tests are yielding position accuracies of two meters, and the system is forecast to be operational in 2005, when it will also provide integrity alerts and accuracy corrections for Russia’s Glonass and Europe’s future Galileo satnav systems.

SBAS (satellite-based augmentation system) is a generic ICAO term commonly used outside the U.S. to describe EGNOS, WAAS and MSAS.

GBAS (ground-based augmentation system) is equivalent to the FAA’s LAAS. Cat I GBAS should become operational in Europe at roughly the same time as Cat I LAAS, about 2006. GBAS airport systems–dubbed MARs, for monitoring and reference stations–are currently in development, and are pacing Airbus plans to install GBAS/LAAS receivers in an A320 for certification trials in 2005.

Galileo will be Europe’s equivalent to GPS, and its 30 satellites will enhance satnav performance and redundancy for all users. First launches are forecast for next year, but lacking the nuclear-hardened casings and classified military loads of the GPS satellites, up to eight of the much smaller and lighter Galileo satellites can be launched on a single rocket, versus just one for GPS. Consequently, a full Galileo constellation is forecast for 2008. At that point, the Europeans will overtake the U.S.’ lead in satnav, since all Galileo satellites will transmit the additional L5 civil frequency required for satnav Cat I precision approaches. This capability is not expected from GPS much before 2020.

The Europeans have designed and are building EGNOS, GBAS and Galileo to be receiver equivalent to WAAS, LAAS and GPS, and transitioning from one to another will be both seamless and transparent to pilots.