Menu Sign In Contact FAQ
Welcome to our forums

RNAV approaches - GS and minima

How do you anticipate what minima to expect and how to anticipate whether there will be an advisory glide slope on an RNAV/RNP approach?

For the approaches to ESGP Säve it is easy. On the plates there are LPV minima.

And on the GPS you see LPV when you select the approaches.

But then it gets trickier.

The approache to ESTA Ängelholm RWY 32 only has LNAV/VNAV and LNAV.

The GPS is able to provide glide slopes for LNAV/VNAV.
But since I know that the procedure has not been coded to allow EGNOS derived glide slopes it makes sense that the GPS shows LNAV as the minima.

In Germany the situation is supposedly different and EGNOS enabled glide slopes are ok.

Let’s look at the RNAV approach to EDDE Erfurt RWY 10 that has LNAV/VNAV and LNAV minima.

Based on based on that EGNOS can be used for vertical guidance I would expect the GPS to show LNAV/V as the expected minima but it only shows LNAV.

I have not flown any RNAV approaches in Germany that have LNAV/VNAV minima but no LPV minima. But what do you really get when you fly them? Do you get any glide slope?

Finally. Advisory glideslopes.

I thought that as long as an RNAV approach only has LNAV minima (no LNAV/VNAV and no LPV) there would be an advisory glide slope.

EKRK Roskilde RNAV RWY 03 do not have any LNAV/VNAV minima and no LPV minima.
Actually it has a GPS minima? Whatever that means? Is that an old way of saying LNAV?

I would expect the GPS to show LNAV+V but it only shows LNAV.

I have not flown the approach into Roskilde so I do not know if you actually get an advisory glide slope or not.

Can I expect a glide slope when flying the approach into EDDE Erfurt?
Can I expect an advisory glide slope when flying the approach into EKRK Roskilde?


Are you perhaps asking whether there is a way of detecting if the “continuous descent profile” (CDP) e.g.

is coded in your database and, if so, does your GPS (which must be a “W” box) output vertical guidance for it, via both a CDI and coupling to an autopilot?

That vertical profile feature is also called LNAV+V.

IMHO, the EKRK RWY 11 GPS approach

will not have the +V in the database – because there isn’t a straight line from the FAF to the MAP.

Unfortunately I am not familiar with the Garmin depiction/annotation which would indicate the exact way you can tell. I know for a fact that many pilots with “W” boxes don’t know this either, and turn up at an approach (like the Shoreham EGKA one above) which does have +V coded but for some reason they find the vertical guidance doesn’t happen.

Also the vertical guidance feature is disabled if

  • it is not an LPV approach, AND
  • there is a “higher grade” (higher than +V) type of vertical guidance charted and in practice, Europe, this means a BARO-VNAV approach, which few light GA planes are certified for.

This stupidity was supposed to be fixed by Garmin years ago but I don’t know if they have done it, and exactly how because obviously they were not going to de-publish the BARO-VNAV option. One case was Southend EGMC.

Shoreham EGKA, United Kingdom

The only reliable way to tell if you are going to get +V is the load the approaches as you have on your GTN650 and see if it says +V. Yours don’t so you won’t get the guidance. If you are flying an LNAV+V your MDA is the LNAV minima.

EGTK Oxford

Where is the +V shown?

Shoreham EGKA, United Kingdom

Where it says “RNAV 03 gps LNAV” it would say “RNAV 03 gps LNAV+V”

EGTK Oxford


I still fail to understand what criteria that prevents an advisory glide slope to show for EKRK RNAV RWY 03.
But it is good to know the GPS will show LNAV+V when advisory glide slopes can be expected.

Peter, on the GTN650 I guess that it would look like this if there will be an advisory glide slope.

What about LNAV/VNAV? Is anyone aware of any approaches where the GTN would display LNAV/V to indicate LNAV/VNAV minima?
I fail to see why it wouldn’t show LNAV/V at EDDE.


You can see it 25 seconds into the attached video.

The problem is that if there is a Baro-VNAV coded it won’t seem to show the SBAS LNAV/VNAV approaches. I thought they were trying to get this fixed but it seems not fixed yet.

[video fixed – you have to use the “Share” URL]

Last Edited by JasonC at 17 Dec 12:08
EGTK Oxford

The link didn’t work for me. But after a little Googling I found it here:

Good to know that what the GPS shows is what you can expect.

I guess that I will just have to accept that it is not possible to anticipate these things at home when preparing a flight.


Maybe there is a GTN PC simulator which, if you can load a current database into it, might show this stuff?

Shoreham EGKA, United Kingdom

I guess so. For advisory glide slopes I do not think that it is such a big deal. The glide slope is definitely nice to have but does not affect the MDA.
But it seems strange that there is no better way of knowing if you should plan to use the LNAV/VNAV minima or LNAV minima.
In the approach I used as an example the LNAV MDA is 130 ft higher than the LNAV/VNAV DA and to me it makes sense that you should be able to figure out which one you can plan with without starting a GTN simulator.

87 Posts
Sign in to add your message

Back to Top