If avionics manufacturers really listen to their customers and we have no reason to believe they don’t theyve been hearing a not-so-subtle thrumming sound of impatient fingers tapping glareshields, anxiously awaiting the arrival of real glass for aftermarket installations. Garmin primed the pump last summer with its announcement of the G600 display-only version of the G1000 EFIS suite, but it hasnt exactly been 
That leaves Avidyne one down in the uncertain but inevitable hopscotch toward glass systems even the owner of a 30-year-old Bonanza can afford. In October, Avidyne inched closer to that reality, but for the time being, only King Air owners need apply. Teaming with autopilot giant S-TEC, Avidyne revealed its first aftermarket application for the well-regarded Entegra EFIS system. Suggestive of a joint venture, the new product is called Alliant and it represents the first aftermarket integrated flight deck system suitable for airplanes not necessarily built in Renton or Toulouse. (Or Savannah, for that matter.)
With its FlightLogic system, Chelton has been plying the somewhat limited market for glass in older airplanes for several years, but whats significant about Alliant is that it marries the glass panel to a new, clean-sheet autopilot design. (Even Garmin is just beginning to do the same, but only for OEM aircraft, not older airframes.)
Avidyne calls its share of the system Envision think of it as essentially a gen-and-a-half Entegra while S-TECs part is the IntelliFlight 2100, a box that can be considered among those rarest of birds: a new digital autopilot.
Outwardly, the Envision looks just like the Entegra in a Cirrus, but rather than a PFD and an MFD, it has two PFDs with independent, cross-referencing ADAHRS and an Avidyne EX500 centerstack for MFDs duties, including traffic, weather, lightning and the C-MAX Jeppesen-based flight library. Besides the dual ADAHRS, the Envision is more tightly integrated with the autopilot than the driver of a single-engine piston might be accustomed to. All of the APs functions are annunciated on the PFDs and the two systems are designed to work together such that the airplane can be flown from wheels up to wheels down on autopilot?