Any opinions on the Garmin GNS 480 ! ! !

I am thinking seriously about getting the GNS480 and need opinions to
(try and) change my mind. The GNS 430 is nice but the 480 has more
features that I like. Anybody using one and making approaches? With
autopilot? with GPSS? Does GPS altitude REALLY work?

Yes to all those questions, except that I don't have GPSS.
Others do have GPSS, and I'm told it works great.

A note regarding the autopilot question...
Our autopilots can capture the GPS glideslope only on approaches
which list VNAV minima.
For LNAV approaches without VNAV minima, if the profile
shows a dotted line representing the glidepath angle (most do),
the GNS480 presents an HSI-like display with vertical guidance,
but that vertical guidance is not sent to the external GS pointer,
thus preventing the autopilot from locking onto the glideslope.
Lateral guidance, of course, remains available to the autopilot.

"RonLee" wrote in message =
...
I am thinking seriously about getting the GNS480 and need opinions to
(try and) change my mind. The GNS 430 is nice but the 480 has more
features that I like. Anybody using one and making approaches? With
autopilot? with GPSS? Does GPS altitude REALLY work?

I don't know where you are located but Carolina Avionics in Salisbury,
NC (RUQ) put in a 530 for the same price as a 430. Not a reman or
refurbish. In fact, I had the same pricing on another 530 in when I bought
another A36 Bo'.

I don't work for them, I just like good service and value.

FWIW, the WAAS and terrain s/b put next year. For the difference in
screen size and added functions, I would go w/ a 530, if I could.

Victor J. (Jim) Osborne, Jr.


ps: If you do call the, tell Bill (Smoot) I said to call, he should
remember me.
N100DA & N326DK

On Tue, 28 Dec 2004 23:26:58 GMT, RonLee wrote:

I am thinking seriously about getting the GNS480 and need opinions to
(try and) change my mind. The GNS 430 is nice but the 480 has more
features that I like.

Anybody using one and making approaches?

Yes

With autopilot?

Yes

with GPSS?

Don't have that.

Does GPS altitude REALLY work?

What do you mean by that?

The GPS glide slope really works for those approaches for which it is
enabled.

The GPS altitude varies from the pressure altitude due to earth shape
assumptions, and other factors including temperature.

However, my install included an encoding altimeter with a 10 ft resolution.
This allow baro-VNAV approaches. It also allows the pressure altitude to
be read directly on the display.

I, too, chose the 480 over the 430 (as well as over the 530) because of
WAAS, the ability to enter flight plans using airways, TSO146
certification. It has a better display than the 430, although smaller than
the 530.



--ron

RonLee wrote:
I am thinking seriously about getting the GNS480 and need opinions to
(try and) change my mind. The GNS 430 is nice but the 480 has more
features that I like.

Anybody using one and making approaches?

Yes

With autopilot?

Yes

with GPSS?

Yes

Does GPS altitude REALLY work?

Yes, but it does not matter, since wrong or right, baro altitude is what
the IFR system uses.

I can't comment on the 480. It has WAAS, but so will the 480. The 480
has no HSI, but there isn't room for it on the display, and in any case,
I have a real HSI, and an electronic HSI cannot emulate a true HSI
in any case.

Great, I just started the "real vs. fake" HSI argument again :-)

--
Samiam is Scott A. Moore

Personal web site: http:/www.moorecad.com/scott
My electronics engineering consulting site: http://www.moorecad.com
ISO 7185 Standard Pascal web site: http://www.moorecad.com/standardpascal
Classic Basic Games web site: http://www.moorecad.com/classicbasic
The IP Pascal web site, a high performance, highly portable ISO 7185 Pascal
compiler system: http://www.moorecad.com/ippas

Good does not always win. But good is more patient.

"Scott Moore" wrote in message =
news:GdKBd.8300$wu4.6369@attbi_s52...
RonLee wrote:
=20
Does GPS altitude REALLY work?
=20
Yes, but it does not matter, since wrong or right, baro altitude is =
what
the IFR system uses.
=20
I can't comment on the 480. It has WAAS, but so will the 480. The 480
has no HSI, but there isn't room for it on the display, and in any =
case,
I have a real HSI, and an electronic HSI cannot emulate a true HSI
in any case.
=20
Samiam is Scott A. Moore
=20

WAAS/GPS altitude is used for VNAV approaches.
It works very well, really.
Baro-VNAV is beyond the scope of the CNX80/GNS480.

I'm curious why you say that the 480 has no room for an HSI display.
Have you never seen its NAV page?
I, too, have a "real" HSI in the lower half of my flight director,
but the HSI page in my CNX80 remains useful to me.
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.

"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

"Mike Adams" wrote in message =
news:HxXBd.6305$232.4499@fed1read05...
"John R. Copeland" wrote:
=20
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.=20
=20
=20
I just took delivery on my GNS480 upgrade, and in the initial test =
flight, did not see what you are=20
experiencing. We flew the GPS23 approach into P08 (Coolidge, AZ), and =
the GPS07R into KDVT=20
(Phoenix, Deer Valley), and VNAV guidance was provided on the external =
HSI in both cases. Interestingly,=20
these are traditional GPS approaches, not the newer ones with specific =
LPV or LNAV/VNAV minimums,=20
and VNAV was provided in both cases. In the Coolidge case, we took it =
all the way down, and it split the=20
runway laterally and the G/S pointer took the altitude right to the =
threshold. All this out in the middle of the=20
desert with no ground navaids. Very cool.=20
=20
So, I'm confused by what's causing your restrictions. Could it be =
something specific to your F/D-A/P=20
setup? I don't have either one, so maybe the logic is restricted only =
if there's an autopilot. Or perhaps=20
WAAS updating was unavailable when you tried it. Is it restricted even =
when WAAS is known to be=20
working?
=20
Mike

That's intensely interesting, Mike. I haven't had WAAS unavailable.
But if it were unavailable, the CNX80 wouldn't show its computed
glideslope presentation on its internal NAV display, either.
Feedback I got from the Apollo tech rep through my avionics shop
said that it was an intentional restriction on driving the VDI needle,
intended to foil 3-axis autopilots from locking onto the vertical
guidance unless VNAV minima were published as part of the approach.

I don't know if the CNX80/GNS480 can be "aware" of whether the
airplane is equipped for 3-axis coupled approaches. Perhaps.
Since I had one of the very first upgrades to CNX80 version 2,
now I'll need to check to see if that VDI restriction was later =
relieved.
Indeed, I originally expected to see the VDI active in my flight =
director,
and that's why I questioned its behavior after my first test flight.
Thanks for those details, Mike.
If you hear anything more about this, please post.

Regarding "splitting the runway", I have an MX20 MFD also,
and it almost always depicts me closer to the centerline of a
runway than to either edge. It's amazing!

Greetings,
The autopilot limitations comes from the autopilot manfacturer, not the
GPS at this point. Apparently the TSOs for the GA autopilots were not
designed or flight tested for LNAV/VNAV and LPV approaches. I expect
these problems to be resolved in the near future so we can let 'George'
fly to minimums with the GPS and be able to snooze just a wee bit
longer.

Mike, two questions: Were either of those GPS approaches flown coupled?
What is the date and version of your GNS480 (or CNX80) software?
Fly SAFE!
Jedi Nein

On Sun, 02 Jan 2005 15:23:47 GMT, "John R. Copeland"
wrote:

WAAS/GPS altitude is used for VNAV approaches.
It works very well, really.
Baro-VNAV is beyond the scope of the CNX80/GNS480.

I wonder why that is, since my encoding altimeter interfaces with my CNX80.
So, if I enter the altimeter setting, I will get a fairly accurate altitude
readout (within 10-20' of my panel altimeter).


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.

Well, I just picked up my a/c with the upgraded CNX80. Due to time
constraints, I did not do anything other than fly home and execute the GPS
Rwy 15 approach at KEPM. In any event, this is an LNAV approach with only
LNAV minimums. However, it does have vertical guidance as evidenced by a
screened descent line; a vertical rate of descent/GS table; and also a TCH
at the rwy end MAP.

Although there are no VNAV minima published, I DID receive vertical
guidance on both the NAV page of the CNX80 as well as on the VDI of my
external NSD360 HSI. So, clearly, there was nothing in my CNX80 inhibiting
external VDI on this approach.

I don't understand why your FD doesn't receive vertical guidance on
approaches where it is provided.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)