"John R. Copeland" wrote:

As I've posted earlier, the glide-slope needle in my Flight Director
is not driven from the CNX80/GNS480 unless VNAV minima are published.
This defeats autopilot coupling to the computed glideslope on
non-precision approaches. However, the HSI display of the NAV page
shows vertical guidance for most LNAV approaches, as a welcome aid for
stabilized descents.


I just took delivery on my GNS480 upgrade, and in the initial test flight, did not see what you are
experiencing. We flew the GPS23 approach into P08 (Coolidge, AZ), and the GPS07R into KDVT
(Phoenix, Deer Valley), and VNAV guidance was provided on the external HSI in both cases. Interestingly,
these are traditional GPS approaches, not the newer ones with specific LPV or LNAV/VNAV minimums,
and VNAV was provided in both cases. In the Coolidge case, we took it all the way down, and it split the
runway laterally and the G/S pointer took the altitude right to the threshold. All this out in the middle of the
desert with no ground navaids. Very cool.

So, I'm confused by what's causing your restrictions. Could it be something specific to your F/D-A/P
setup? I don't have either one, so maybe the logic is restricted only if there's an autopilot. Or perhaps
WAAS updating was unavailable when you tried it. Is it restricted even when WAAS is known to be
working?

Mike