Jim sez:
This file contains the xml and updated rgb for an APR button on the
autopilot. It can be used to lock on to the glide slope on an
ILS aproach.
As it stands now the NAV locks onto the NAV1 localizer and the APR locks
on to the NAV1 GS (if it exists). I think (and I'm not quite sure) that on a
real autopilot (like the KAP-140) the NAV button will lock on to VOR signals
and the APR is used for locking to localizer/ils for both axiis. But without
having a manual and knowing exactly how this should work, and making further
changes to the autopilot code, this slight modification will make it easier to
lock onto a glideslope on approach.
