GI275 HSI

[midlifeflyer]

Has anyone seen a display like this? No, the second white segmented CDI is not a bearing pointer.

 

[Mooney Dog]

That looks like its armed to capture a nav source, but i am unsure. Normally when stuff on Garmin's are white, its set to capture. Do you have an autopilot coupled with the system? 

[midlifeflyer]

Thanks. That was my first thought too but I don't recall ever seeing an "armed" course indicator in advance of a CDI change.

[Mooney Dog]

Ive not used the 275 much, so again i am unsure. Where you flying on an approach or something that switches nav sources? 

[midlifeflyer]

2 minutes ago, Mooney Dog said:

Ive not used the 275 much, so again i am unsure. Where you flying on an approach or something that switches nav sources? 

It's not mine. It's from a pilot I do training with. But yes, it was on an approach where nav sources would switch, so the "arming" makes logical sense. But I just have not seen this behavior in any HSI or CDI or PFD, glass or gas, and it's not something documented in the 275 manual.

[Mooney Dog]

1 minute ago, midlifeflyer said:

It's not mine. It's from a pilot I do training with. But yes, it was on an approach where nav sources would switch, so the "arming" makes logical sense. But I just have not seen this behavior in any HSI or CDI or PFD, glass or gas, and it's not something documented in the 275 manual.

Thats where my confusion comes from. I went and looked at the manual for the 275 and saw nothing of the sort as well. Maybe its a new feature that hasnt been updated yet? Or is the plane you where flying in experimental by chance? 

[midlifeflyer]

25 minutes ago, Mooney Dog said:

Thats where my confusion comes from. I went and looked at the manual for the 275 and saw nothing of the sort as well. Maybe its a new feature that hasnt been updated yet? Or is the plane you where flying in experimental by chance? 

Definitely not experimental. Weird, huh?

I was able to download the July 2021 version of the Pilot Guide. Nothing there.

a bearing pointer would make sense since it would indicate its nav source. But this CDI doesn't give any indication. 

 

Edited August 14, 2021 by midlifeflyer

[N231BN]

VLOC Preview

[carusoam]

@KLudwick might have seen something like that….(?)  (GI275 mystery…)

Or know somebody with some insight…

Best regards,

-a-

 

[midlifeflyer]

6 hours ago, N231BN said:

VLOC Preview

Sent from my Pixel 4a using Tapatalk
 

Yep. That's the answer. Thank you! It's called the:

"Lateral and Vertical Guidance Preview
"The MFI can preview the lateral and vertical guidance pointers on the correct final approach course when an ILS, LOC, BC, LDA, or SDF approach is active in the external navigator and the navigator is using GPS until intercepting the final approach NAVAID."

Someone in another group pointed it out in the Pilot Guide (page 45 in the current Revision G). It's a setting available when the 275 is being fed by a GTN.

Edited August 14, 2021 by midlifeflyer

[Mooney Dog]

4 hours ago, midlifeflyer said:

Yep. That's the answer. Thank you! It's called the:

"Lateral and Vertical Guidance Preview
"The MFI can preview the lateral and vertical guidance pointers on the correct final approach course when an ILS, LOC, BC, LDA, or SDF approach is active in the external navigator and the navigator is using GPS until intercepting the final approach NAVAID."

Someone in another group pointed it out in the Pilot Guide (page 45 in the current Revision G). It's a setting available when the 275 is being fed by a GTN.

Interesting. I wonder if that works for other GPS such as the 175 or 375, or if it only applies to the 650 750 units.

[midlifeflyer]

2 hours ago, Mooney Dog said:

Interesting. I wonder if that works for other GPS such as the 175 or 375, or if it only applies to the 650 750 units.

I wouldn't expect it to. Those are GPS-only units. No VLOC signal to feed to anything.

But a few things I discovered in follow-up.

As I suspected, the feature is not limited to GI 275. When I play with the Garmin PC trainer, I usually pair a GTN with a GDU PFD/MFD. Same behavior. I'm a little surprised I never came across it before. I guess I'm usually doping out a GPS procedure so I don't have a VLOC approach loaded.

It's funky on VOR approaches. "preview the lateral and vertical guidance pointers on the correct final approach course." Works fine with a LOC signal since it's always tied to the FAC. But with a VOR signal, you have to manually enter the course for the pointer to be correct. For example, in the photo I started with, the KRWI VOR/DME 22, approach, the "phantom VLOC" needle is points to a course of 115°. The FAC on the approach is 238°.  I think it picks  up whatever radial you are on at the time it activates rather than reading FAC information from the GPS. . can sort of see the feature's usefulness for an ILS - might even be a good "change CDI" reminder. But for a VOR approach, I'd rather keep the pink needles and toss in a green bearing pointer for the raw data.

 

Edited August 14, 2021 by midlifeflyer

[Mooney Dog]

4 hours ago, midlifeflyer said:

Those are GPS-only units. No VLOC signal to feed to anything.

oops, duh. Thats a good point. Thanks for the info! 

[KLudwick]

On 8/13/2021 at 9:12 PM, carusoam said:

@KLudwick might have seen something like that….(?)  (GI275 mystery…)

Or know somebody with some insight…

Best regards,

-a-

 

Sorry for the tardy reply, but glad other MS’ers beat me to the punch.  Yes, that’s the lateral guidance preview - or as I call it, the ghosted needle.  Gives you a bit more situational awareness as you’re coming up on the localizer, for instance.  My GI 275 install starts in just a few weeks - can’t wait to have these features in my Mooney!

[midlifeflyer]

On 8/18/2021 at 12:04 AM, KLudwick said:

Sorry for the tardy reply, but glad other MS’ers beat me to the punch.  Yes, that’s the lateral guidance preview - or as I call it, the ghosted needle.  Gives you a bit more situational awareness as you’re coming up on the localizer, for instance.  My GI 275 install starts in just a few weeks - can’t wait to have these features in my Mooney!

I went over it with the pilot who asked me and he asked me to do a short video of doing a VOR approach- the one he did. Since there is no Garmin 275 emulator, I used the 700P GDU which is probably as close as we can get.  It's pretty raw so it definitely not YouTube material without some editing but in the process I learned a few things. 

On 8/14/2021 at 12:02 PM, midlifeflyer said:

 I think it picks  up whatever radial you are on at the time it activates rather than reading FAC information from the GPS. .

That's wrong. Like any VOR CDI, you have to input the desired radial manually. All it is doing when it activates (Terminal mode; VOR as the active waypoint) is carry over  the CDI OBS setting from the last time you set it. Of course! That was a "duh" moment for me. 

On 8/14/2021 at 9:29 AM, Mooney Dog said:

until intercepting the final approach NAVAID

Well...maybe. Here's the thing. The expectation there is that you are going to change the CDI to green needles. That's fine but, based on the simulation, you lose something.  The approach my friend did, the KRWI VOR 22 has a nice 3.01° glidepath, and Garmin was nice enough to treat it as LNAV+V and provide an advisory glidepath.  But only when yo are navigating via GPS. Change the CDI to green needles and the vertical guidance goes away (we will probably check that out in flight next time we go up together).  What is unclear to me is whether the "Preview" or "Phantom" or "Ghosted" is sufficient "raw data" when doing a VOR approach. I think it should be. Switching back and forth between hosted and actives results in the same course, but personally, I kind of prefer the bearing pointer.

Edited August 21, 2021 by midlifeflyer

[Fly_M20R]

On 8/13/2021 at 7:11 PM, midlifeflyer said:

Has anyone seen a display like this? No, the second white segmented CDI is not a bearing pointer.

 

 

I have not seen that kind of display in my setup. However, I do not have a second GPS, NAV/COM or GPS/NAV/COM connected to my bottom unit.

I have not seen any documentation on dual HSI’s being displayed at the same time. It may be a configuration issue.

Disclaimer: I have not read all posts yet, only the first two so the answer may have been already posted…

Chris

Edit: Well…. Just read through and answer HAS been posted by N23BN and nicely followed up by midlifeflyer!! I had skipped over that section since I have a GNS530 and not a GTN unit. Also may not have it in my configuration because I only have a GNS.