GPS NAVIGATORS & GPSS The development of GPSS has created a great deal of interest in the General Aviation community because it successfully integrates current and future GPS technology directly with the autopilot and flight controls of light General Aviation airplanes. In our GPSS design process, S-TEC engineering chose ARINC 429 digital data for several reasons. First, over the years, 429 has become an established aviation industry standard used by many avionics manufacturers. Second, the data messages we needed to make GPSS work were already defined in the ARINC 429 specification. These are partly the result of the General Aviation Manufacturers Association (GAMA) working closely with ARINC in the definition of data labels in the 429 specification. One question that we are being asked very frequently is "does my XYZ GPS Navigator have the composite 429 output GPSS needs?" When we introduced GPSS at EAA AirVenture in Oshkosh, we knew which GPS Navigators had the correct data for our GPSS, at that point in time. However, we are aware that many of the GPS manufacturers that do not provide the data we process to produce GPSS may be designing their products to provide the data in the future. Obviously, as time goes on, keeping track of who does and who does not output the correct data for GPSS will be increasingly more difficult. You and your customers will get a more reliable, timely answer by asking that question of the GPS manufacturer directly.