Glide Path Capture with GNS530

[ark 1,288]

I cannot seem to get the GNS530 to capture the Glide Path during a GPS RNAV approach. I have tried both the original Asobo GNS530 and the PMS50 GNS mod. The approach is selected and activated in the GNS530, and does work laterally, but there is no GP response at all. I have also tried a couple of different airports. What's the 'trick' to make this work?

Thx,

Al

Edited June 20, 2021 by ark

[Bert Pieke 7,584]

23 minutes ago, ark said:

What's the 'trick' to make this work?

To wait for WT to fix the Garmins... they currently do NOT work correctly..

In the interim, suggest flying ILS approaches 🙂

Edited June 20, 2021 by Bert Pieke

[ark 1,288]

3 hours ago, Bert Pieke said:

To wait for WT to fix the Garmins... they currently do NOT work correctly..

In the interim, suggest flying ILS approaches 🙂

Hi Bert,

Well, that's actually good news.  I've been helping Mark with a simple autopilot for his Flysimware Grumman G-44A Widgeon for MSFS, and have been pulling my hair out trying to figure out why some approach code I put together would not work for GPS approaches, because it does work well for ILS approaches. There's just not that much difference in the code. So thanks for helping to save what little hair I have left!

Al

Edited June 20, 2021 by ark

[ryanbatc 12,836]

Yeah kinda a bummer.  Only option which isn't necessarily a wonderful one is to get the TDS GTN Xi.  If and only if you have the autopilot enabled will it fly an RNAV(GPS) approach to LPV mins.  There is no guidance on the gauges yet unfortunately with the TDS GTN.

[scotchegg 4,186]

The 172 classic which I spend most of my time in follows it in rnav. I did two flights (Japan and US) yesterday and it worked ok.

[Bert Pieke 7,584]

2 hours ago, scotchegg said:

The 172 classic which I spend most of my time in follows it in rnav. I did two flights (Japan and US) yesterday and it worked ok.

OK, is not what we are after...  We are expecting correct glidepath capture like the real unit offers.   No airport I have seen is coded correctly for an RNAV LPV approach..

Just like an ILS approach, an RNAV LPV approach only activates the glideslope indicators when you turn to final, and shows them at the top of the HSI gauge, so you intercept from below.

If you have got an example where this works, please provide details!  🙂

[SAPilot 213]

5 hours ago, ark said:

I cannot seem to get the GNS530 to capture the Glide Path during a GPS RNAV approach. I have tried both the original Asobo GNS530 and the PMS50 GNS mod. The approach is selected and activated in the GNS530, and does work laterally, but there is no GP response at all. I have also tried a couple of different airports. What's the 'trick' to make this work?

Thx,

Al

The APPR mode must be activated before the IAP for the RNAV approach. I know the indicators are all over the place as Bert indicated, but try that If you haven't done it.

[ark 1,288]

1 hour ago, SAPilot said:

The APPR mode must be activated before the IAP for the RNAV approach. I know the indicators are all over the place as Bert indicated, but try that If you haven't done it.

Yes, I been activating the Approach early, but still don't get any glide path needle indications, and when on autopilot the plane does not start descending at the FAF.

Thx,

Al

[ark 1,288]

4 hours ago, scotchegg said:

The 172 classic which I spend most of my time in follows it in rnav. I did two flights (Japan and US) yesterday and it worked ok.

To be very clear, the GNS530 will do lateral navigation, including during the approach. What it won't do is capture the glide path and descend during an LPV approach (which is much like an ILS approach).

Al

Edited June 21, 2021 by ark

[Bert Pieke 7,584]

As I said... WT is working on it..

[scotchegg 4,186]

3 hours ago, Bert Pieke said:

Just like an ILS approach, an RNAV LPV approach only activates the glideslope indicators when you turn to final, and shows them at the top of the HSI gauge, so you intercept from below.

Sorry, I’m in over my head here as I don’t know how the real thing should work. Just know it took me down at an angle roughly in line with the PAPIs.

[Bert Pieke 7,584]

19 hours ago, ark said:

Well, that's actually good news.  I've been helping Mark with a simple autopilot for his Flysimware Grumman G-44A Widgeon for MSFS

@ark I would suggest getting in touch with the WT guys.  They are very approachable and can tell you where they are at.. 🙂

[styckx 1,871]

I'm not the sharpest tool in the shed but doesn't all RNAV do is keep you center line? The glide slope is entirely in the pilots hand. I've only done it once or twice because I'm used to ILS approaches I just stick with it. RNAV is just GPS.. ILS is an actual landing system. 

Edited June 21, 2021 by styckx

[ark 1,288]

25 minutes ago, styckx said:

I'm not the sharpest tool in the shed but doesn't all RNAV do is keep you center line? The glide slope is entirely in the pilots hand.

No. There are RNAV(GPS) LPV approaches that provide vertical guidance to the runway much like an ILS approach. The vertical guidance is called a Glide Path for an LPV approach vs a Glide Slope for an ILS. The minimums for an LPV approach are usually about the same as for a typical ILS approach -- typically about 200 ft.

See https://skyvector.com/files/tpp/2106/pdf/00087RY35L.PDF and note the criteria for the LPV approach.

Al

Edited June 21, 2021 by ark

[styckx 1,871]

Just now, ark said:

No. There are RNAV(GPS) LPV approaches that provide vertical guidance to the runway much like an ILS approach. The vertical guidance is called a Glide Path for an LPV approach vs a Glide Slope for an ILS. The minimums for an LPV approach are usually same as for a typical ILS approach -- about 200 ft. See https://skyvector.com/files/tpp/2106/pdf/00087RY35L.PDF.

Al

Thanks boss man. Appreciate it..