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GPS approach only, alternate required?

Asked by: 5756 views Instrument Rating

Are you required to file an alternate if your destination airport only has a GPS approach?

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  1. John D. Collins on Feb 24, 2012

    My understanding is that the rules for requiring an alternate are based solely on the forecast weather as described in 91.169 and not the type of approach.  However, 91.205 requires that the aircraft have navigation equipment suitable for the route being flown.  If you have a TSO C129A GPS (non WAAS GPS), it is only approved as supplemental means of IFR navigation and would require other navigation equipment suitable for the route being flown, for example a VOR receiver.  If you have a WAAS GPS in full compliance with TSO C145/146, it may be used as the sole means of IFR navigation and meets the 91.205 requirements.  If the weather forecast dictates you need an alternate, for the TSO C129A GPS, the alternate may not be a GPS  or RNAV approach and you may not plan on using the GPS in lieu of a DME or ADF at the alternate for a ground based approach. For a complying TSO C145/146 WAAS GPS, you may use a RNAV (GPS) approach if it is approved for use as an alternate, but your planning must be based on the LNAV non precision alternate minimums (typically 800-2).  You also may plan on using a ground based approach that requires the GPS be used in lieu of a DME or ADF.

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