Can a standalone GNSS receiver (i.e. a receiver not used for navigation) be used as position source, for input to the transponder, to meet the ADS-B mandate in Europe?
AMC1 CS ACNS.D.ADSB.090(a) states that the data transmitted by the active ADS-B transmit unit should be consistent with the data displayed to the flight crew.
Consistency may be demonstrated by using a compliant GNSS sensor connected to the transponder and the navigation equipment (i.e. transponder and navigation equipment receive the same data from the GNSS source) .
Where this is not possible, consistency may be demonstrated by the installation of a standalone GNSS receiver connected (only) to the transponder providing the GNSS receiver is approved to ETSO-C145c or C146c (or later ETSO amendments). Note: Operational Class 1, 2, or 3 of RTCA DO-229D, satisfy the ‘consistency’ criteria.