WAAS is unquestionably a revolutionary technology for the IFR pilot. With no ground infrastructure at all, we can now be guided as low as an ILS to any piece of pavement at any airport. Even airports without a WAAS approach benefit as the vertical accuracy of WAAS allows for an advisory glidepath to MDA on plain-vanilla GPS approaches.
Well, to airports in North America, anyhow. The biggest limit of WAAS is that as it depends on geo-stationary satellites, the coverage area is limited to the parts of the planet over which those satellites “hover”. Travel outside these areas and GPS technology steps back to the pre-WAAS era.
That’s why the recent declaration of the EGNOS systems as safety of life (SOL) capable is great news. EGNOS, or European Geostationary Navigation Overlay Service, is the European version of WAAS, both of which are generically called Space Based Augmentation Systems (SBAS).
EGNOS covers most of Europe
EGNOS has been operational for several years, and in March was declared ready for critical SOL operations, such as aviation. Within a week a Falcon 900 flew the first LPV approach in Europe, to Pau Pyrénées in the south of France.
Garmin has already upgraded the G1000 to be capable of using EGNOS guidance. When the navigation database cycle 1101 was installed in G1000 systems in early January, it also unlocked EGNOS capability. Pressing the SBAS soft key on the GPS status page now shows EGNOS in addition to WAAS and MSAS (the Japanese version).
G1000 is now EGNOS ready
Unfortunately it will be some time before full benefit of EGNOS is realized. To start, not very many airports in Europe have approaches with LNAV/ VNAV or LPV minimums, with only France and Germany having any in large numbers. Further, even those that do may prohibit use of EGNOS until flight checking is complete. A recent trip into Hamburg, Germany (EDDH) turned up the following NOTAM:
“Use of SBAS- (EGNOS-) signals for APV- Baro VNAV operations prohibited until further notice. Use of LNAV/ VNAV minima with a certified Baro VNAV system…still permitted.”
So while LNAV/ VNAV minimums are published to EDDH, they can’t be flown yet via EGNOS. This will change with time, and European operators will enjoy the benefits of SBAS approach aiding we’ve enjoyed in the US for several years.
