No Autoswitch with the GI275?

[jlunseth]

I replace my old King 256 and 525 with dual reversionary 275’s. I kept the KFC 200 AP. With the old system I had a GTN750Xi connected to the King system through an Icarus SAM GPSS and that is still the case with the 275s. With the old system, when an approach is activated the ILS frequency was loaded as the standby Nav frequency. If the pilot then switched it to be the primary frequency prior to the FAF, the system would Autoswitch from GPS mode to VLOC mode, so the final approach course would be flown using the Localizer and glideslope. I have been putting the new system through its paces, and one of the things I discovered was that the system would not Autoswitch. I talked to my installer, who thought it should but then went through the 275 manual and found this material:

“Guidance Source Auto-Switching and Prompting
When interfaced with a compatible and appropriately configured Garmin GPS Navigator 
with a compatible Garmin NAV receiver, the MFI's displayed deviation source automatically 
changes based on certain conditions.
If the aircraft has passed the MAP on an ILS/LOC approach, the guidance source switches 
to GPS.
If on an ILS/LOC approach and the correct frequency is tuned, GPS is selected as the current 
guidance source, and the AFCS is roll-coupled to a localizer, the guidance source automatically 
switches to ILS/LOC before the FAF. Auto-switching only occurs with a GFC 600 autopilot and 
a GTN series navigator that is interfaced with the MFI.
When on an ILS/LOC approach but GPS is selected as the guidance source, the CDI Button 
flashes to prompt the crew to switch guidance sources.”

So, it looks like Autoswitch does not happen with the 275s (unless you also buy a 600). Can anyone confirm or tell me my conclusion is wrong?

[PeteMc]

I know other people that have the 275s as their PFD and I believe it works for them.  I'd first confirm that the AutoSwitch didn't somehow get turned Off in your GTN.  (Unlikely, but you never know.)

On your comment about switch to the Active Frequency, well, unless you are using the GTN to navigate with a VOR, don't wait.  As soon as you load the Approach, go make the ILS Active.  The reason it doesn't do that on it's own is because you might be using a VOR and it doesn't want to mess you up. 

The switch occurs if you are withing 1.2NM of either side of the LOC and are more than 2NM and less than 15NM from the FAF.  So if you're waiting until you're close to the FAF to switch the Freq to Active, you may be too close.

Other option is that the installer didn't configure something correctly when they interfaced to the 275s.

 

[Ragsf15e]

2 hours ago, jlunseth said:

I replace my old King 256 and 525 with dual reversionary 275’s. I kept the KFC 200 AP. With the old system I had a GTN750Xi connected to the King system through an Icarus SAM GPSS and that is still the case with the 275s. With the old system, when an approach is activated the ILS frequency was loaded as the standby Nav frequency. If the pilot then switched it to be the primary frequency prior to the FAF, the system would Autoswitch from GPS mode to VLOC mode, so the final approach course would be flown using the Localizer and glideslope. I have been putting the new system through its paces, and one of the things I discovered was that the system would not Autoswitch. I talked to my installer, who thought it should but then went through the 275 manual and found this material:

“Guidance Source Auto-Switching and Prompting
When interfaced with a compatible and appropriately configured Garmin GPS Navigator 
with a compatible Garmin NAV receiver, the MFI's displayed deviation source automatically 
changes based on certain conditions.
If the aircraft has passed the MAP on an ILS/LOC approach, the guidance source switches 
to GPS.
If on an ILS/LOC approach and the correct frequency is tuned, GPS is selected as the current 
guidance source, and the AFCS is roll-coupled to a localizer, the guidance source automatically 
switches to ILS/LOC before the FAF. Auto-switching only occurs with a GFC 600 autopilot and 
a GTN series navigator that is interfaced with the MFI.
When on an ILS/LOC approach but GPS is selected as the guidance source, the CDI Button 
flashes to prompt the crew to switch guidance sources.”

So, it looks like Autoswitch does not happen with the 275s (unless you also buy a 600). Can anyone confirm or tell me my conclusion is wrong?

This is purely anecdotal, but… I have dual g5s, stec 30 autopilot, gns 430w and it does auto switch.  I would be surprised if yours did not with a newer gps and newer pfd.

[jlunseth]

1 hour ago, Ragsf15e said:

This is purely anecdotal, but… I have dual g5s, stec 30 autopilot, gns 430w and it does auto switch.  I would be surprised if yours did not with a newer gps and newer pfd.

The passage I quoted is from the 275 manual, not necessarily applicable to the g5. I brought this up with the installer and he thought I needed to switch Autoswitch on in the 750. There is a menu in the 750 to do that. The problem was I had already tried, and using the menu does not give me the option to switch Autoswitch on, it is just not there. So he said it should be in a menu in the 275, which is what led me to look through the 275 menu again. 

When I worked through all that and talked to the installer, I had a hunch that the ability to autoswitch needed to be enabled during the install so it would show up in the 750 menu. What I am really fishing for here is whether I should go back to the installer and ask him to take a look at the installation and see if Autoswitch can be enabled. 

[Ragsf15e]

8 minutes ago, jlunseth said:

The passage I quoted is from the 275 manual, not necessarily applicable to the g5. I brought this up with the installer and he thought I needed to switch Autoswitch on in the 750. There is a menu in the 750 to do that. The problem was I had already tried, and using the menu does not give me the option to switch Autoswitch on, it is just not there. So he said it should be in a menu in the 275, which is what led me to look through the 275 menu again. 

When I worked through all that and talked to the installer, I had a hunch that the ability to autoswitch needed to be enabled during the install so it would show up in the 750 menu. What I am really fishing for here is whether I should go back to the installer and ask him to take a look at the installation and see if Autoswitch can be enabled. 

Yeah, I was just thinking that if a g5/430 combo, does it, certainly your setup should.  I would take it back to the installer.  There is also a setting in the gps to do this.  Possibly it isn’t set right there?

[jlunseth]

1 hour ago, Ragsf15e said:

Yeah, I was just thinking that if a g5/430 combo, does it, certainly your setup should.  I would take it back to the installer.  There is also a setting in the gps to do this.  Possibly it isn’t set right there?

Well, I worked through the menu to turn Autoswitch on in the 750. The 750 manual is really clear. When I get to the screen where you can elect Autoswitch the icon simply is not there. I told that to the installer (good shop by the way) and he said it would be directed by the 275, which is what lead me to the section of the 275 manual I quoted. 

[201Mooniac]

I'm not sure of the setup required but it at least works with the GI275 and a GFC-500 so it isn't only the GFC-600 but I don't know if this will work with legacy APs

[PeteMc]

I thought I remembered this discussion over in the FB 275 group, but nothing definitive came up in my search, so I started a new discussion.

One guy who just recently had the same issue found the below video.  Not specifically about the 275 and there is a G500TXi in the mix, but they video shows various settings needed in the GTN and 275.  Might be helpful to check.

https://youtu.be/2QxRUkGLvuE

[jlunseth]

I looked at the video and I hope it will be helpful, although there is a G500 involved and I don't have that. But at the end of the video there is a screenshot of a post about how to make Autoswitch work, and that illustrates where my problem lies. The second bulleted line says: "In the GTN's normal System/Setup page under ILS CDI capture select 'Autoswitch.'". That is where my problem is. When I go into that menu there should be an icon for Autoswitch and it is missing, simply not there in the GTN750Xi. So I can't make that selection.

[PeteMc]

35 minutes ago, jlunseth said:

When I go into that menu there should be an icon for Autoswitch and it is missing, simply not there in the GTN750Xi. So I can't make that selection.

The video did show some settings to check in the 275, so hopefully that will be it.  And I'm 99% sure that I remember other discussions that the button is hidden on the GTN when connected to a 275 (who knows why it can't be left On). 

But I also think hiding or un-hidding the Autoswitch button in the Settings on the GTN is in the Configuration.  And in the video it is obvious turned On, but given it may have been because of the G500.  So maybe a quick call to your Avionics guy or email to Garmin to clarify and ultimately resolve the issue.

 

[jlunseth]

Thanks.

[PT20J]

5 hours ago, jlunseth said:

I looked at the video and I hope it will be helpful, although there is a G500 involved and I don't have that. But at the end of the video there is a screenshot of a post about how to make Autoswitch work, and that illustrates where my problem lies. The second bulleted line says: "In the GTN's normal System/Setup page under ILS CDI capture select 'Autoswitch.'". That is where my problem is. When I go into that menu there should be an icon for Autoswitch and it is missing, simply not there in the GTN750Xi. So I can't make that selection.

It may just be semantics, but the button on the System -Setup page is actually called ILS CDI Capture and it should toggle between Manual Selection and Auto Switch.

[PT20J]

From the GTN Xi AFMS. Appears to only work with GFC 500/600.

[PeteMc]

3 hours ago, PT20J said:

It may just be semantics

Yes, semantics on Garmin's part.  In the GI275 manual they refer to it as "Auto-Switching" and the discussion started from the GI275 side.

Garmin GI 275 Pilot's Guide    190-02246-01 Rev. K    pp 47

 

Edited March 17, 2023 by PeteMc

[PT20J]

Knowing what features are available in a particular Garmin installation can be difficult to discern. I have found that the best source of information is often the AFMS because it is an FAA approved document. In my experience, Garmin's Pilot's Guides vary in clarity and sometimes contain errors. In addition, they describe the operation of a unit, but when multiple unites are combined in a system, the functionality of each unit can change. There are also sometimes installation options that are described in the installation manuals only available to dealers. 

One thing to check here would be that the CDI key is enabled and appears on the Map screen. I didn't see a mention of auto switching in the GI 275 AFMS, but that makes sense since I believe it is the GTN that does the switching.

[37_Fox]

I've been battling this for almost a month now. My installer is also confused and Garmin hasn't been much help either. I have a 750xi, GI275 ADAHRS, and a GFC500 AP. I'll try and keep this short and sweet :-)

Initial systems ops check flight - ILS: 750xi auto switches from GPS to VLOC (indicated at the bottom of the 750xi) but the 275's don't auto switch. They do however flash the "CDI" button at me indicating I need to manually switch. **Pictures 1 & 3 show CDI button (750xi), VLOC, and flashing "CDI" on the 275's**

Then my installer calls Garmin... Garmin tells them to deactivate the CDI button on the 750xi. I now have lost my "ILS CDI Auto Capture" button in the settings of the 750xi and the CDI button is gone from the bottom of the 750xi. Also, you can see on the ADI that "LOC" and "GS" are armed, but yet it never captured them. **Picture 2**

Second ILS attempt - Airplane flies right through final. No flashing CDI button on the 275's either. As soon as I hit the CDI button on the bottom of my HSI or CDI (I have both), it grabs the ILS and turns me towards final. In the maintenance manual, you can turn the CDI button back to active, which will give you the "auto switch" option back under "ILS CDI Auto Capture." I'm starting to think the configuration of the 275's is my problem. I've found several videos demoing this, so I know it's capable, but the correct way to set this up appears to be a mystery. I'll let you know more if we ever get it figured out...

Edited April 6, 2023 by 37_Fox

[carusoam]

Great detailed first post 37_f!

A similar discussion has occurred in a different thread… where a software update covered some ills…

Let me invite a couple of people from that discussion over here…. @midlifeflyer and @donkaye (Big G automation and IFR procedures)

Best regards,

-a-

[37_Fox]

5 minutes ago, carusoam said:

Great detailed first post 37_f!

A similar discussion has occurred in a different thread… where a software update covered some ills…

Let me invite a couple of people from that discussion over here…. @midlifeflyer and @donkaye (Big G automation and IFR procedures)

Best regards,

-a-

Ah! Thank you. I would imagine I’m running the latest software, but you never know.

[midlifeflyer]

 

7 hours ago, 37_Fox said:

Then my installer calls Garmin... Garmin tells them to deactivate the CDI button on the 750xi. 

I don't know the answer in your case. The only thing similar I've seen involves this. I think there are certain things in the GTNxi/Garmin PFD interface that can be configured to be in the control of the GTN or the PFD or both. Sounds like the error is somewhere in there. Might be cabling, might be configuration.

[jlunseth]

@37_Fox The 275 manual says it only works with the GFC600. That said, I am told it is supposed to work with the GFC500 also. I looked at some of the videos earlier in this thread and tried to set my system up using the suggestions in the videos. I ran into two problems. One, they require installer access for some of the settings which I don’t have. Two, the systems in the videos had a G500 and it appeared to me the G500 was “directing traffic,” i.e. coordinating between the GTN and the 275. In a set up with a G500 and a 275, the 275 would be set up as a standby not a primary. In my system it is the primary ADI and there is no G500 to coordinate between the 275 and the GTN, rather, the 275 is in charge. So all I get is what you get, the CDI button flashes at the final approach course to remind me to switch the 275 to VLOC.

[201Steve]

I’ll say this about it, I had several things to bug out with my similar system, and it took test flight after test flight after email after email after phone call after phone call between shop and Garmin, before it was finally discovered that EXAMPLE SOLUTION one of the back end settings wasn’t perfect. To skips point above, the manuals are written with some major equipment assumptions. If those assumptions aren’t met, whether by equipment pairings or installation methods, the information exists somewhere deep in between 2 or 3 different documents. What a cluster F. 

[N231BN]

The GI-275 Manual requires the CDI key to be disabled. This also disables the autoswitch button on the GTN setup page.

Perhaps sometime in the future they will put the autoswitch capability in the GI-275. I really don't see it as that big of a deal, you need to manually switch AP modes anyway.

[Marc_B]

@37_Fox I have G5/GTN750Xi/GFC500 and had issues trying to get this squared away. From what I understand from @donkaye is that this went back and forth with Garmin and settled on GFC500 should auto switch…and mine does. 
I think for me the steps were:

1. Enable the CDI key on GTN. This allows the setup screen to have the “CDI source” set to AUTO and selection of AUTO SWITCH. 
2. set CDI sync on GI275 and GTN to “Always On”. This was the step that finally allows the auto switch. 

There was a thread on BT that talked about this. After a few back and forth with my installer this finally works. 

Good luck!