"Ron Rosenfeld" wrote in message =
...
On Sun, 24 Oct 2004 23:57:17 GMT, "John R. Copeland"
wrote:
=20
However, I have not (yet) found in the pilot's manual any
explanation of when VDI drive is withheld from an external HSI.
By flying several different kinds of approaches, I seem to see
that the external VDI will be active *only* when VNAV minima apply.
Only on precision approaches having DH instead of MDA,
my autopilot could arm and capture the glideslope,
exactly the same as an ILS.
On non-precision approaches my external VDI needle remained
driven out of view, even though its glide-slope flag was pulled,
and as a result I could not arm the glide slope for automatic capture.
=20
John,
=20
I won't be upgrading my CNX80 until the end of December, but in =
Newsletter
5 from Garmin there is a description indicating that Glideslope =
guidance
should be available on your HSI for LNAV/VNAV, LPV *and* =
"non-precision
approaches with defined vertical paths" so long as the HPL or VPL =
minimums
for the approach are not exceeded.
=20
Perhaps something has changed since that document was written; or =
perhaps
there's a glitch in your wiring.
=20
--ron

Ron, I no longer have newsletter 5, but I can't fault the newsletter =
announcing=20
availability of the version 2 upgrade, because the new NAV display in =
the
CNX-80 performs as the attachment to that newsletter described.
For LNAV approaches, I have not found where that attachment promised
glide-path guidance on an external indicator, only on the internal NAV =
display.

The undocumented part concerns the drive to the external VDI in my =
flight director.
Wiring can't be faulty, because it works flawlessly on ILS and VNAV =
approaches.
My avionics installer promised today to inquire about that with his =
factory rep.
If I get clarification, I'll share it here.
---JRC---