If it's a standard RNAV it won't have a glideslope - just follow the step-down on the chart to get an accurate approach.  Now, I've had a GS intercept on some RNAVs but I certainly don't expect them - I activate APR mode at the indicated altitude before the final fix and it will sometimes engage a GS.

Basically, I enter the next altitude and initiate a 500 fpm descent.  If no GS lock appears, I just follow the step-down.  I've had occasions where, having begun my descent, I get a GS indication and she locks in.

1 hour ago, RandallR said:

If it's a standard RNAV it won't have a glideslope

Read the post before yours..

I just took the C172 Classic (steam gauge) up and flew the RNP RWY 03L patern at my local airfierld Sywell EGBK and the plane flew the glidescope on APR autopilot (not sure if you still need Navigraph to see this approach or whether it's in the default data yet)

As with the Carenado aircraft the CDI doesn't show glideslope information during RNAV but the autopilot flies it just fine.

Edited June 21, 20214 yr by Matchstick

2 hours ago, RandallR said:

If it's a standard RNAV it won't have a glideslope

I'm not sure what you mean by "standard RNAV", but there are GPS LNAV approaches that only provide lateral guidance - much like a Localizer only approach. There are also LNAV/VNAV approaches that provide both vertical and lateral guidance like an LPV approach, but the guidance is not as precise and so the minimums are typically higher than for an LPV approach.

Since there is no expensive ground equipment for a GPS LPV approach like there is for an ILS (no localizer or glide slope antennas, etc) many small airports that could not justify or afford the expense of installing and maintaining an ILS approach now have GPS LPV or LNAV/VNAV approaches. I'm sure there is some expense in 'installing' an RNAV LPV or LNAV/VNAV approach (site evaluation and approval by the FAA, etc), but I have no idea what a typical cost might be to acquire an LPV approach. It would be interesting (at least to me  🙂 ) to see how that compares to a comparable ILS installation.

For a brief overview on GPS approaches see:

https://www.boldmethod.com/learn-to-fly/navigation/what-is-the-difference-between-lpv-and-lnav-vnav-gps-approaches/

Al

Edited June 21, 20214 yr by ark

Just completed a flight into KPIH (Pocatello) using the RNAV Rwy 3 approach (it is LPV capable).

Shortly after I initiated a descent in the last stage of the profile, a GS lock did occur and provide an assisted descent.  I was using the GTN750.

48 minutes ago, RandallR said:

Just completed a flight into KPIH (Pocatello) using the RNAV Rwy 3 approach (it is LPV capable).

Shortly after I initiated a descent in the last stage of the profile, a GS lock did occur and provide an assisted descent.  I was using the GTN750.

Thanks for the feedback. I problem we have been discussing seems limited to the Asobo default GNS430/530 (and associated mods) as far as I know.

Al

1 hour ago, ark said:

Thanks for the feedback. I problem we have been discussing seems limited to the Asobo default GNS430/530 (and associated mods) as far as I know.

Al

Nope, it is the MSFS flight plan logic, period.

Edited June 21, 20214 yr by Bert Pieke

59 minutes ago, RandallR said:

Just completed a flight into KPIH (Pocatello) using the RNAV Rwy 3 approach (it is LPV capable).

Shortly after I initiated a descent in the last stage of the profile, a GS lock did occur and provide an assisted descent.  I was using the GTN750.

Which is still not correct..

1 hour ago, RandallR said:

GS lock did occur and provide an assisted descent.

You didn't say which a/c you were using. Assuming you had an HSI on the panel, was the HSI GS/GP indicator (pointer) activated as you approached the FAF (YOGUT)? Did the autopilot fly the descent or were you hand flying?

Thx,

Al

35 minutes ago, ark said:

Did the autopilot fly the descent

Al, you can see all this in the default C172 with G1000.

As WT will tell you, the underlying flightplan logic in MSFS is broken.  😉

No amount of "I flew an RNAV approach and it worked" can fix this.

 

13 minutes ago, Bert Pieke said:

Al, you can see all this in the default C172 with G1000.

As WT will tell you, the underlying flightplan logic in MSFS is broken.  😉

No amount of "I flew an RNAV approach and it worked" can fix this.

 

Hi Bert,

OK, I get it. I haven't really tried flying with any of the GTN750 freeware offerings, so was curious what users are seeing. You would think RNAV approaches are important enough and common enough to have garnered Asobo's attention loooong ago. In any case, since you indicate WT is working on it there is hope for the not too distant future.

I appreciate the info.

Al

Edited June 21, 20214 yr by ark

6 minutes ago, ark said:

You would think RNAV approaches are important enough and common enough to have garnered Asobo's attention loooong ago.

Garmins have been at the top of the user wish list for close to a year now, which ultimately got WT hired by Microsoft... since Asobo had no expertise (or time) to deal with it.

1 hour ago, ark said:

You didn't say which a/c you were using. Assuming you had an HSI on the panel, was the HSI GS/GP indicator (pointer) activated as you approached the FAF (YOGUT)? Did the autopilot fly the descent or were you hand flying?

I was flying the C208b w/the pms50-GTN750 mod.  The AP was flying the aircraft and intercepted the flight path (lateral) correctly.  I then initiated descent stages, entering the appropriate altitudes and descent rates into the AP based on the descent profile.

Shortly after I initiated a descent for the final segment, "GS" illuminated on the panel and the AP continued the descent following a glide path which accurately led to the threshold. The glide path indicator (diamond) appeared at the same time as the GS indication, though it hadn't appeared prior (which in the RW, it should have).  It stayed just above the index line which would normally indicate that I was just below the GP.  No amount of power adjustment could get it to move from this position, though the slope itself turned out to be fairly accurate.

Edited June 21, 20214 yr by RandallR

38 minutes ago, RandallR said:

I then initiated descent stages, entering the appropriate altitudes and descent rates into the AP based on the descent profile.

This works for any of the default Garmins... but this is, as you indicated, not real world behavior.    Just like an ILS approach, you should be able to fly at the published approach altitude and intercept the glidepath before the FAF.

Even the TDS suffers from lack of glide path indication unless the AP is flying. Well in that case it will fly but still no glide path visible on analogue gauges.