FAA Updates GPS Advisory Circular

 - April 7, 2014, 11:20 AM

The FAA on March 28 published a revised version of AC No: 20-138D that clarifies and adds new guidance material to the airworthiness approval process for a variety of GPS systems, including augmented GPS, and Rnav equipment for RNP operations and baro-Vnav equipment. Several changes cover the following factors: the differences between equipment capability and installed limitations; clarification of the database configuration and equipment capability; adding step-down fixes to navigation databases; and a new appendix for demonstrating radius to fix (RF) leg capability and required navigation performance (RNP) prediction guidance for RNP authorization required approach (RNP AR APCH). However, this AC does not address new satellite constellations that are planned or currently under construction.