Dual G5, GFC 500, 2 separate nav sources

CRQFlier

CRQFlier

Pre-takeoff checklist
Joined
Jan 22, 2018
Messages
222
Display Name
Display name:
CRQFlier
Final planning on a panel upgrade and ran into something I didn't expect - you can't tie 2 different nav sources to a G5 HSI. At least that's what Garmin support told me. There's no source switch on the G5 and you can't place an external switch.

So does everyone that has a G5 HSI and 2 nav sources have a second indicator? If I get a GPS175 tied to the G5, then there's no way to use the G5 for an ILS?

How about throwing in a GFC500? If the nav tied to the G5 fails does the GFC500 become a wing leveler? Or is there a way to get guidance from the second nav?

Guess I just assumed the G5 could handle multiple nav units.

Thanks for any insight.

Sent from my SM-G960U1 using Tapatalk
 
The navigation source can be selected from the G5 HSI menu to be GPS1, NAV1, GPS2, or NAV2 depending on your equipment. In the case of the GTN 750, it is possible to navigate with GPS all the way until the final ILS approach course and at that moment the navigator (and HSI) automatically switches to ILS. The GFC 500 just follows along. The GFC 500 "NAV" mode uses whatever navigation source the G5 HSI uses at any time. The G5 HSI can only display one source at a time, although it can display additional bearing pointers for other sources. However, another CDI might be nice for doing intersects.

I think G5 may be restricted to a single navigator when both navigators are not Garmin. I guess this is what Garmin Support had in mind.

For whether the GFC 500 would revert to a wing leveler when losing the GPS175, my answer is "maybe". But not because of any navigator source issue. VOR navigation is GPS-aided for the GFC 500. Maybe it would be able use the internal GPS receiver of the G5 for this purpose, but I don't know.
 
That's correct; two sources may be connected, but only if they're both modern Garmin offerings (i.e. a GNS430 + GNC225, or GTN750 + GTN650, etc.)

I still have a KX-155 as my second radio and it's connected to a secondary mechanical CDI.
 
Thanks @CA182R and @Ryan F.

When I spoke to Garmin support I specifically asked about the GPS175 and the GNC255 as Nav1 and Nav2. He said the G5 does not handle 2 nav sources and there is no selection - it only handles nav1.

About the automatic switching GPS to VHF nav with a 650/750 type unit on an ILS approach, I wonder if similar could happen with a 175 and 255? Probably not.

I think I need to call garmin again. My shop wasn't much help - they told me I needed a 106b as a backup to the G5 to comply with the STC.


Sent from my SM-G960U1 using Tapatalk
 
I think I've got it figured out. Reading a bunch on mooneyspace: yes, 2 nav sources can go to a single G5. yes, the G5 will automatically switch GPS to ILS(vhf) nav on an activated ILS approach if the signal is from one unit (e.g. a 650). No, the G5 will not automatically switch GPS to ILS on two separate nav units (e.g. gps175 to gnc255). And no, the G5 does not turn the CDI for the ILS if 2 separate nav units. This all makes sense, but was thrown way of track by the dealer AND garmin tech support.

Sent from my SM-G960U1 using Tapatalk
 
I doubt the switching will happen automatically from GPS to ILS in your scenario. I think the GTN handles that, not the G5.

Btw, I put my GNC 255 in a mode that allows it to display the lateral needle on the GNC itself when pressing the "OBS" button. That way I could practice intersects.

The STC for G5, I think, says this: "cannot interface with dual navigators if G5 is interfaced with a non-Garmin autopilot"
 
Last edited:
CRQFlier said:
I think I've got it figured out. Reading a bunch on mooneyspace: yes, 2 nav sources can go to a single G5. yes, the G5 will automatically switch GPS to ILS(vhf) nav on an activated ILS approach if the signal is from one unit (e.g. a 650). No, the G5 will not automatically switch GPS to ILS on two separate nav units (e.g. gps175 to gnc255). And no, the G5 does not turn the CDI for the ILS if 2 separate nav units. This all makes sense, but was thrown way of track by the dealer AND garmin tech support.

Sent from my SM-G960U1 using Tapatalk
Click to expand...

That sounds right, not sure there's any scenario in which it could work another way. The idea for automatic switching requires the sources be from the same box of course.

I'm confident you'll be able to send multiple sources to the G5 assuming they're all modern Garmin boxes.
 
Thanks @Ryan F. and @CA182R. Super helpful.

Can the SL30 work instead of the GNC255 for nav2? I'm assuming yes.

Sent from my SM-G960U1 using Tapatalk
 
I have 2 nav sources to my G5. One is a 530W and the other is a GNC255. The GPS to ILS switch is done with the CDI button on the 530. That switches the HSI needle from magenta to green. To go to Nav2 you push the knob on the G5, scroll over to source, push knob again and select Nav2.
 
P.S. I believe the key to 2 sources is they have to be 2 digital sources. Anyone have 2 IFDs going to a G5?
 
You must log in or register to reply here.
Back
Top