The Avidyne AHRS can now align while the airplane is moving so there is no need to delay taxiing as there was with early systems. The PFDs are very easy to operate with bezel buttons beside menus used to select modes or change the display. However, to set a target altitude you need to use the knobs on the autopilot control panel, not the PFD. The selected altitude is displayed on the PFD, as are all autopilot modes.
For takeoff I used the normal turbine airplane techniques and selected go-around mode to have a flight director target pitch attitude and heading mode. After liftoff and gear retraction I engaged the yaw damper and autopilot and put it to work in bumpy air. The yaw damper is powerful and effective and has a feature that as far as I know is unique to S-Tec-yaw damper trim. A little knob on the panel allows you to fine-tune rudder trim without touching the mechanical rudder trim tab control.
The 2100 autopilot flies the King Air well, and is unusually gentle and gradual in its altitude captures or pitch changes. Many of the new digital autopilots in turbine airplanes are able to capture altitudes or make airspeed or vertical speed changes quickly with absolute smoothness, but the 2100 does the job cautiously, much like a very careful and precise human pilot would fly.
I climbed out in airspeed hold mode and the 2100 captured the assigned altitude with no need for extra button pushing to arm the system. When you engage vertical or airspeed hold modes they come up synchronized to the present speed, and then you can adjust up or down using a rocker switch on the autopilot control panel. The selected target values appear on both the PFD and autopilot control.
The Alliant system uses GPS roll steering commands from the Garmin 430s to capture and track nav or approach courses, and that, too, was smooth and precise. I even pulled one power lever all the way back to idle with the other side at high power while in a rapid descent and, after one or two yaw excursions to catch up, the autopilot then flew the airplane perfectly despite the great drag of the idling propeller on the left side. Part of that performance is from the rudder bias system in the King Air that automatically steps on the proper rudder when an engine is pulled back, but much of the engine-out capability also comes from the powerful yaw damper in the 2100 system.
To give the system a really tough - even unfair - test, I flew toward the localizer at an 80-degree angle just a couple miles outside the outer marker with approach mode armed. To add to the challenge, I threw out approach flaps and landing gear at near maximum speed as the little airplane on the moving map neared the ILS line. The autopilot grabbed for the centerline as soon as the localizer came alive and rolled aggressively to capture the signal. It did fly through the course, as you would expect, but with only one excursion to correct, it captured the ILS and was stable on the centerline as we got to the marker. This system can handle the worst vector a controller can ever give you.
The Alliant system doesn't quite match a complete glass cockpit because it leaves the mechanical engine gauges in place, and doesn't have a large MFD, but I think those are excellent tradeoffs for the price. By getting rid of the old mechanical gyros, and a whole bunch of wiring and remote avionics boxes, the conversion will also save a bunch of weight, about 50 to 150 pounds, I would estimate, in many installations. Removing the old gyros and avionics boxes also opens up space in the nose for a baggage compartment that is available as an airframe modification.
There is a lot of life left in thousands of King Airs, and the Alliant conversion will allow these graceful and comfortable turboprops to live out their years with a new heart.