IFD > Aerocruze 100 VNAV

I had the Aerocruze 100 autopilot installed last winter, and haven’t always been able to change my selected altitude while in GPSS mode, and when it wouldn’t allow me to change it I just settled for SVS 0 mode instead.

I’ve now figured out why. When the Aerocruze is in GPSS and there is an altitude assigned to the next waypoint of an IFD active flight plan, the Aerocruze will place that altitude in the SEL box and won’t allow it to be changed, such as the 3,500’ target at the first waypoint, KCQF, below. In this case, the Aerocruze SEL box will contain 3500, and cannot be changed manually with the Aerocruze KNOB.

In the above flight plan the approach waypoint altitudes starting at RUPQE are prefilled in of course, and the autopilot GPSV mode flies them as expected. But I added the 3500’ to the KCQF waypoint as a test, and it is recognized by the Aerocruze and its SEL box is populated with 3500.

So for me, when in GPSS and there is an altitude associated with the next Avidyne waypoint, if you want to change altitude you have no option other than to change that waypoint’s altitude in the IFD FMS, since you can’t change it on the Aerocruze head.

I have a Dynon PFD, so ignore the GPS/PFD selector switch below, and you’ll see my IFD is connected to the Aerocruze with 429 A&B lines as per the STC.

Is this Enroute Vertical Navigation that supposedly isn't possible unless you have a Garmin GTN connected to a Garmin autopilot? I’d like to get confirmation that this is normal operation from others with an IFD and Aerocruze 100.