WAAS/SBAS
The Garmin aera is listed as featuring WAAS/SBAS.
SBAS means 'Satellite Based Augmentation Systems' - the current SBAS are WAAS, EGNOS and MSAS which are mutually compatible to provide international SBAS coverage. These systems are satellite supported Differential GPS (DGPS) which is not the same as the 'Ground Based Augmentation System' (GBAS) which requires an additional receiver to provide DGPS augmentation. GBAS using VHF should provide sufficient accuracy for precision approaches in future years; GBAS using 300KHz MF/LF receivers is also available, primarily for maritime use.
The WAAS (Wide Area Augmentation System) is available in America, EGNOS (European Geostationary Navigation Overlay System) is the European equivalent, while MSAS (Multi-functional Satellite Augmentation System) operates in Asia, particularly in Japan.
EGNOS currently uses 2 Inmarsat and the Artemis satellites, but will later use new Astra satellites Astra 4B (due to launch in a couple of months time) and Astra 5B (due to launch next year).
Garmin EGNOS satellite IDs are 33 (Inmarsat 3F-2 at 15.5W), 37 (Artemis at 21.5E) and 39 (Inmarsat 4F-2 at 25E). The satellites are in geostationary equatorial locations, so are quite low on the horizon as well as being much further from the earth than the GPS constellation. Inmarsat moved its satellites over the past few years to optimise its global coverage; Artemis took nearly 2 years to reach the correct orbit after an Ariane 5 launch vehicle failed to deliver it correctly.
You will find a HUGE number of out of date websites and other erroneous information on the Internet concerning EGNOS satellites.
So yes, your Garmin aera should indeed be EGNOS capable. From Booker aerodrome, look in the arc between about 195šT and 155šT for EGNOS satellites.
Last edited by BEagle; 19th Feb 2012 at 08:44.