My two cents worth: any autopilot that acts in that manner is probably
best not used for "coupled" approaches. I put "coupled" in quotes
because a truely coupled approach would be independent of the heading
bug once the localizer has been captured.

The kludged-up situation you describe could be hazardous during
demanding circumstances.

Roy Smith wrote:

In article ,
"Jeremy Lew" wrote:


Don't know anything about that A/P, but I was under the general impression
that if an A/P is in APR or NAV mode, it is following the CDI needle (or
possibly the GPS?). The heading bug is used for HDG mode.


Well, the manual says:

"In systems equipped with a DG, during an instrument approach, the
heading bug must be set to match course for the segment of the approach
being flown when using the NAV, APR, or REV modes. course pointer."

Unfortunately, the manual is big on rote descriptions of which buttons
to push when, and says damn near nothing about how the thing actually
works inside. I'm left with guessing at its operating logic based on
observed behavior and some theoretical knowledge of control systems.

Clearly, setting the heading bug 10 degrees off the desired course was a
mistake, but the manual doesn't even begin to talk about the best way to
correct the mistake. Just resetting the bug to the right setting
resulted in course oscillations. What I'm trying to figure out is what
might have been a better course of action.