In the quest for the optimal exploitation of the benefits of dual-frequency multi-constellation (DFMC) systems, the aviation community has committed to the development of new avionics standards for the GNSS equipment flown on commercial aircraft. Such efforts also open the possibility to more deeply analyze certain phenomena by taking advantage of modern simulation tools that were not available or were only partially available at the time that single-frequency models were first defined. With the removal of first-order ionospheric errors due to dual-frequency pseudorange measurement combinations, the remaining user errors (noise, antenna, multipath) become more relevant and are the dominant error sources that have to be addressed and properly bounded for performance-based navigation (Circiu et al., 2017;Salabert, 2015).