Doug wrote:

But really, you don't need DG coupling. It
makes failure modes MUCH more complicated.

Having an autopilot coupled to a GPS is the cat's pajamas.

At least around here, I spend a nontrivial amount of time on vectors.
That's much easier with an AP connected to the DG.

A vacuum failure that goes unnoticed while one is still on HDG mode would
mean either circles or a bad heading. Not a good thing, but still not the
same as had the AP been using the (now failed) AI.

Can an AP get heading information from the GPS? It can get track; is that
close enough?

At least at this moment, I cannot figure out how I'd tell the GPS to fly a
particular heading from the current position. Anyone know how to do that
in a Garmin 430?

- Andrew