What are some of the other issues that need to be addressed when upgrading the GNS-400/500 series to include WAAS capability?
The WAAS upgrade for the GNS-400/500 series units is not a ‘plug and play’ upgrade. There are several installation, certification, and operational subjects that must be adhered to before a proper WAAS upgrade can be completed. For aircraft with dual GNS-400/500 series units, both units must be upgraded for the crossfill function to operate. A WAAS upgraded 400/500 series unit will not crossfill to a non-WAAS 400/500 series unit. One subject that many people upgrading to WAAS may overlook involves the GPS navigators distance from the pilot’s primary field of view. The original GNS-400/500 series installation guidelines only provided general suggested guidelines for the distance of the unit from the pilot’s primary view. Page 2- of the WAAS GNS-400/500 installation instructions is very specific in regards to the suggested guidelines for this distance. The left edge of the GNS unit should be no more than 11.8 inches from the centerline of the pilot’s field of view. The 500 series units al
