Current State of "How To" for Rnav Approaches?

[mikeklimek 151]

Hey guys, I'm trying to figure out how to do rnav approaches in MSFS, and the more I search and read, the more confused I get.  Trying to learn about rnav approaches in general combined with the fact that the sim is said to be bugged in various ways around rnav compounds the confusion for me.  Here's a typical scenario for me (default Cessna 172, steam gauge version):

• I'll create a fight plan which includes the rnav approach.
• As the gps turns me toward the airport and runway, I select APR on the autopilot (I believe I'm usually doing this somewhere between the IAF and FAF and am at the published altitudes).  
• However, I get no vertical glide slope and the plane just continues to fly at my current altitude without stepping down, taking me over the airport.

1) As of today, May 2, 2021, is rnav still considered bugged in MSFS?

2) If so, would it make a difference if I used the g530 mod?

3) Would someone of whom it works in this sim be so kind as to give a step-by-step guide on what to do and when (presuming they found a workaround)?

4) If providing a workaround, perhaps also describing how it SHOULD work in comparison?

Thanks guys.  I'm pulling my hair out because it's just not clicking for me why I can't get it to work.

 

Edited May 2, 2021 by mikeklimek
Clarity

[WarpD 824]

An RNAV approach is not guaranteed to have a vertical guidance.  An LPV has vertical guidance, an LNAV+V has vertical guidance, an LNAV has no vertical guidance.  All three of those approaches are RNAV approaches.

[hangar 661]

53 minutes ago, mikeklimek said:

Hey guys, I'm trying to figure out how to do rnav approaches in MSFS, and the more I search and read, the more confused I get.  Trying to learn about rnav approaches in general combined with the fact that the sim is said to be bugged in various ways around rnav compounds the confusion for me.  Here's a typical scenario for me (default Cessna 172, steam gauge version):

• I'll create a fight plan which includes the rnav approach.
• As the gps turns me toward the airport and runway, I select APR on the autopilot (I believe I'm usually doing this somewhere between the IAF and FAF and am at the published altitudes).  
• However, I get no vertical glide slope and the plane just continues to fly at my current altitude without stepping down, taking me over the airport.

1) As of today, May 2, 2021, is rnav still considered bugged in MSFS?

2) If so, would it make a difference if I used the g530 mod?

3) Would someone of whom it works in this sim be so kind as to give a step-by-step guide on what to do and when (presuming they found a workaround)?

4) If providing a workaround, perhaps also describing how it SHOULD work in comparison?

Thanks guys.  I'm pulling my hair out because it's just not clicking for me why I can't get it to work.

 

As WarpD has suggested, not all RNAV's feature vertical guidance. I'm not sure that you can tell the difference between an LPV Rnav and a LNAV+V Rnav because I'm not so certain that the msfs GPS indicator for that is actually functioning currently so....in case it's not then...to know if a particular RNAV approach offers vertical guidance check it's associated real world chart and look for the "WAAS" label in the upper left corner of the chart. If there is a "WAAS" label then yes, it will offer vertical guidance.

If you are already flying a waas enabled approach and you still dont get any vertical guidance then im not sure what your issue may be.

[Alpine Scenery 1,609]

3 hours ago, mikeklimek said:

1) As of today, May 2, 2021, is rnav still considered bugged in MSFS?

2) If so, would it make a difference if I used the g530 mod?

3) Would someone of whom it works in this sim be so kind as to give a step-by-step guide on what to do and when (presuming they found a workaround)?

4) If providing a workaround, perhaps also describing how it SHOULD work in comparison?

Thanks guys.  I'm pulling my hair out because it's just not clicking for me why I can't get it to work.

 

It depends on the plane, your settings, the particular airport, how you enter the flight plan, and all that stuff. I haven't played Xplane in quite a while, so I forget how a true RNAV works precisely (I will go read up as a refresher a bit later), but here is how it works in the game anyhow...

1) Yes, but IMO, for many planes the bug is VERY minor. For instance, in the default KingAir (unmodded), you can do an RNAV, but it starts descending too late, and it requires you to come under the glide slope just like an APPR ILS, when it should (I think) allow set the VPATH or VGP up several miles in advance. However, you do NOT have to hit the approach button as long as the last waypoint is lined up to the airport relatively proper, it will go into APPROACH mode automatically. Also, the game is not going to show you the correct RNAV indicator on many planes, sometimes it may use the VPATH/VNAV indicator or a VGP, this is just the programmers mixing it up I think.

2) It's hard for me to recall every plane and exactly how every RNAV worked, but I do remember these two (KingAir and DA-62). 

3) I don't think RNAV works at all in the FBW, but it does in the WT-CJ4 to the extent that it's more like a fake VNAV than an RNAV. Though I must say I am having a lot of issues with the CJ-4 lining up to the runway properly lately, it often comes in at an angle.

4) Main thing is just to experiment, there are so many little quirks that it's hard to really outline them all, you just have to experience it yourself. Once you do it successfully, then just repeat.

 

 

Edited May 2, 2021 by Alpine Scenery

[mikeklimek 151]

Thanks guys, these answers have already been helpful, much appreciated.  I experienced this most recently at KTYS: https://skyvector.com/files/tpp/2104/pdf/00218R5R.PDF

I thought it would work as the chart says 'WAAS' at the top left, but taking a closer look, I notice now there's a asterisk footnote that it's "LNAV only" seemingly from the FAF of VOYUR to the runway (doh!).  Guess that would explain that one.  Curious though, why would it say 'WAAS' but simultaneously be 'LNAV only'?  As indicated earlier, doesn't 'WAAS' mean vertical guidance is provided?

I'm going to find a chart specifically with LPV or LNAV+V and keep practicing.

Edit: Actually now I'm thinking I may be misinterpreting the asterisk, at least just after the FAF.

Edited May 2, 2021 by mikeklimek

[Alpine Scenery 1,609]

As far as I know, MSFS does not make any distinction in functionality, if it says RNAV in the dropdown, you have vertical guidance. Maybe I am wrong, but I have yet to see any differences between vertical guidance at any place I have landed, the only difference I find at different airports are TOD issues, where the TOD marker is oddly close to the last waypoint, or there is a circular pathing problem where it turns you.

If the vertical guidance fails, it's a safe bet that there are some bad entries in the airport's navigation settings, or the RNAV got bugged out (it happens). Be prepared for the AP to crash you into the ground sometimes, that's just the way it goes.

Edited May 2, 2021 by Alpine Scenery

[Alpine Scenery 1,609]

14 minutes ago, mikeklimek said:

Curious though, why would it say 'WAAS' but simultaneously be 'LNAV only'?  As indicated earlier, doesn't 'WAAS' mean vertical guidance is provided?

I'm going to find a chart specifically with LPV or LNAV+V and keep practicing.

I usually use this site:

https://www.airnav.com/airport/KTYS

 and just scroll to the bottom. It's easier because I just google "airnav ICAO" and it always comes up, not certain the info is any better, but it does indicate CHANGED which is often the issue.

Edited May 2, 2021 by Alpine Scenery

[hangar 661]

21 minutes ago, mikeklimek said:

why would it say 'WAAS' but simultaneously be 'LNAV only'?

Well, the "waas" part is referring to the equipped hardware capability of your aircraft, and the LNAV/LPV refer to the "minimums" requirement by the FAA.

So...WAAS is basically a hardware/software feature that needs to be installed in an aircraft in order to see the vertical guidance...and the LNAV/LPV are your minimums restrictions...

so, if your plane is waas enabled then you can fly the vertical guidance down to the published LPV minimums...if your plane is NOT waas equipped than you are restricted to the LNAV published minimums.

Of course we're talking about real world technicalities here and so all this has little to no real relevance  in the sim, unless you are practicing real world processes.

Edited May 2, 2021 by hangar

[Alpine Scenery 1,609]

I think RNAV actually works better on most planes without GPS mods unfortunately, that's probably why so many say it's broken.

 

Edited May 2, 2021 by Alpine Scenery

[Bobsk8 12,681]

1 hour ago, WarpD said:

An RNAV approach is not guaranteed to have a vertical guidance.  An LPV has vertical guidance, an LNAV+V has vertical guidance, an LNAV has no vertical guidance.  All three of those approaches are RNAV approaches.

It's amazing that some just don't get this and keep trying to get an LNAV  approach to give them vertical guidance..

[Alpine Scenery 1,609]

One of the bugs is if you set it to LNAV but choose RNAV from the dropdown in the menu, then some planes will automatically enter the approach without hitting the approach button. I know this isn't technically an RNAV, but that's why it's so confusing. It also works differently on every plane and every MOD, so there is no rule here for the sim regardless of how it works in real life. That is why some are confused about LNAV giving vertical guidance, it actually can in some cases in this game.

Edited May 2, 2021 by Alpine Scenery

[mikeklimek 151]

5 minutes ago, Bobsk8 said:

It's amazing that some just don't get this and keep trying to get an LNAV  approach to give them vertical guidance..

Not sure if you're directing this specifically at me.  I would've thought at this runway https://skyvector.com/files/tpp/2104/pdf/00218R5R.PDF it would've been possible (WAAS at the top left).  I get that generally not ALL rnav approaches offer vertical guidance.  Just trying to figure out what I'm missing for those where it appears it is possible.  

I don't know what to say, I'm trying to learn.  Maybe when I know as much as some of you, I can forgo threads/questions such as these.  🤷‍♂️

I'll figure it out.  Thanks guys. 

[Bert Pieke 7,584]

2 hours ago, mikeklimek said:

Thanks guys.  I'm pulling my hair out because it's just not clicking for me why I can't get it to work.

Welcome to the club!

This discussion has been ongoing since MSFS was first released.

As several folks have said: You cannot expect RNAV in MSFS to work like the real thing, because its basic underpinnings have been incorrectly designed and implemented.

The vertical guidance in particular is badly broken.

In the real world, RNAV approaches are designed to safely route you to the final runway course, at altitudes that correspond to local terrain topography.

The glidepath is not activated on your instrumentation until the FAF is the next active waypoint.

At that time, a Garmin GPS will indicate the nature of the approach: LNAV, LNAV+V, LPV etc.

Also, in the case of LNAV+V or LPV, the glideslope indicator on your HSI will activate, and be above you if you are flying at the correct altitude.

None of this works correctly in MSFS.

You can safely stop pulling out your hair  🙂

 

Edited May 2, 2021 by Bert Pieke

[Bert Pieke 7,584]

19 minutes ago, Alpine Scenery said:

I think RNAV actually works better on most planes without GPS mods unfortunately, that's probably why so many say it's broken.

 

Sorry to disagree, as I have explained above, the basics are not correctly implemented...

GPS mods or not.

[Bobsk8 12,681]

2 minutes ago, Bert Pieke said:

Welcome to the club!

This discussion has been ongoing since MSFS was first released.

As several folks have said: You cannot expect RNAV in MSFS to work like the real thing, because its basic underpinnings have incorrectly designed and implemented.

The vertical guidance in particular is badly broken.

In the real world, RNAV approaches are designed to safely route you to the final runway course, at altitudes that correspond to local terrain topography.

The glidepath is not activated on your instrumentation until the FAF is the next active waypoint.

At that time, a Garmin GPS will indicate the nature of the approach: LNAV, LNAV+V, LPV etc.

Also, the glideslope indicator on your HSI will activate, and be above you if you are flying at the correct altitude.

None of this works correctly in MSFS.

You can safely stop pulling out your hair  🙂

 

LNAV (Lateral NAVigation) (aka GPS NPA) — A nonprecision approach that uses GPS and/or WAAS for LNAV. Lateral sensitivity does not increase as the aircraft gets closer to the runway. Pilots may use a WAAS-enabled GPS for LNAV, but WAAS is not mandatory. Vertical guidance is not provided.Sep 7, 2018