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Aircraft Systems

What is the difference between DGPS or Differential GPS and LAAS or Local Area Augmentation System? Both appear to be a GBSS or ground based as opposed to satellite based. I know that all Garmin products are capable of receiving DGPS data but I think that is transmitted via UHF while the LAAS information is transmitted via VHF. But could I fly an LAAS approach to CAT I minimums with the 430W unit? I see there are some LAAS approaches at KEWR now and they only go to CAT I minimums.

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  1. John D. Collins on Nov 06, 2012

    If you want to learn more about DGPS and GBAS or LAAS, read http://en.wikipedia.org/wiki/Differential_GPS and http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/laas/ .

    DGPS is a generic term for Differential GPS of which WAAS could be considered a member, although mostly DGPS refers to the Coast Guard system and is used by surveyors whereas the WAAS system is totally a satellite based system,

    None of the Garmin GPS aviation navigators receive the Coast Guard DGPS. The GNS430W receives the WAAS system on the same frequency as the standard GPS (L1 – 1575.42 MHz). The WAAS correction information is operated by the FAA whereas the base GPS system is operated by the Defense Department. The WAAS system leases transponders on three geostationary satellites over the equator and they relay the correction information to the WAAS GPS receivers such as the GNS430W.

    The GNS430W has no support for ground based augmentation, so no, the GNS430W can’t fly a GLS approach.

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