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mikeklimek

Current State of "How To" for Rnav Approaches?

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Posted (edited)
1 minute ago, Bert Pieke said:

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

GPS mods or not.

I agree the indicators aren't correct, I don't agree that every plane cannot do it, but then again I would have to verify every little nick and cranny to make sure it was up to standards. But in some situations, I have done what appears to be a correct RNAV exactly as you stated.

Edited by Alpine Scenery

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1 minute 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  🙂

 

LOL, thanks Bert.  That would explain some of my confusion, at least when researching it on the MSFS side.  👍

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Posted (edited)
3 minutes ago, Bobsk8 said:

LNAV:  Vertical guidance is not provided.

I have edited my post to clarify the difference.

Edited by Bert Pieke

Bert

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18 minutes ago, hangar said:

So...WAAS..

Is also a North American nomenclature 🙃 Europe uses EGNOS, MSAS (Japan), GAGAN (India) etc...

All are examples of Satellite based augmentation system (SBAS). WAAS is just the american flavor. I even think My real Garmin Unit fails WAAS check during pre-flight.


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Posted (edited)
9 minutes ago, Bert Pieke said:

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

GPS mods or not.

There is not a consistent functionality in the bugs, there are 4 things mixing together and it's quite complicated. So just saying "it doesn't work", well depends what you mean by that. It's not that the basics are NOT implemented, it's that every plane has varying auto-pilot issues and GPS issues, because the underlying tie-in code varies between the various GPS functonality.

1) Bugs triggered within the last 10 miles

2) It being in the wrong mode and it showing the wrong indicator

3) Certain planes have a state bug where it will show ALT-V or VPATH with a GP lock but it's really stuck in VS- mode, so it crashes you into the ground. 

I have definitely done at least a simulated RNAV in the DA-62 and one of the Carenados, now if this was 100% proper, I cannot say, but I'll review again later to check my altitudes against the real approach.

 

Edited by Alpine Scenery

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7 minutes ago, Alpine Scenery said:

But in some situations, I have done what appears to be a correct RNAV exactly as you stated.

Well done! 🙂

This has been broken for me in every airplane I have tried with a Garmin GPS in the panel.

Cannot comment on CJ4, A320 etc..


Bert

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3 minutes ago, Alpine Scenery said:

It's not that the basics are NOT implemented

Not to split hairs.. they are implemented, but implemented incorrectly..

Reread my post above outlining the issues.. :cool:


Bert

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Posted (edited)
27 minutes ago, Alpine Scenery said:

There is not a consistent functionality in the bugs

Sorry to harp on this, but if Asobo/WT is ever reading this, I would want them to see clearly where they need to focus.

There is a consistency that I can see across any Garmin equipped airplane.

Activating the approach, also activates the glideslope indicator, and if you were to follow this indicator, you would end up at the FAF intercept altitude. This is true even at the beginning of the approach.

In the real world, the glidepath extends beyond the FAF, and the correct GS (or GP as it is called for RNAV) intercept should happen well before the FAF, exactly like an ILS approach.

And as I said above, the GS indicator does NOT activate until the FAF is the next waypoint.

Edited by Bert Pieke
  • Like 1

Bert

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Posted (edited)

Hmmm, the bugs even change depending on if you manually activate the approach in the GPS or just leave it from the dropdown. The problem is people are loading external flight plans, modding GPS, and there are too many variables.

Maybe you are doing it the same way every time in the same order since I'm guessing your a real pilot, I'm randomizing the order and going in and out of a lot of modes to try to force it to work.

Edited by Alpine Scenery

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Posted (edited)

@mikeklimek the vertical guidance is working at your kyts waas approach. But it intercepts at the Xizmo intersection @ the published altitude of1840msl instead of the FAF...which means for this particular approach that vertically speaking you're on your own to get down to the published 1840msl alt at XISMO, then upon passing Xizmo your glideslope indicator in the plane should begin dropping so youll have the vertical guidance to the runway at that point (visually speaking on your g/s needle...i never use autopilots for approaches as my preference so icant say your autopilot will be useful or not).

Since the RNAV approaches in the sim have not been properly implemented by the developers, you'll find that most waas approaches will not be useful until you reach the published FAF and its associated altitude, and in some cases the waypoint following the FAF (as in this particular case).

...and don't feel bad or shy away from asking anything around here that you're not sure of...because most of us are just figuring this all out as we go and are in the same boat as you...we're all on the same team so no need to feel shy about it 😉

Edited by hangar
  • Like 3

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Posted (edited)
10 minutes ago, Bert Pieke said:

Activating the approach, also activates the glideslope indicator, and if you were to follow this indicator, you would end up at the FAF intercept altitude. This is true even at the beginning of the approach.

In the real world, the glidepath extends beyond the FAF, and the correct GS (or GP as it is called for RNAV) intercept should happen well before the FAF, exactly like an ILS approach.

I don't activate the approach when I'm in VGP mode, and even on the KingAir you don't press the Approach button (ever) when doing an RNAV, or that means the RNAV failed. I am not sure what you mean by activate the approach?

You mean activating in the GPS, well I cannot say as I would have to keep an ongoing spreadsheet of all the conditions that i find, but I think people are being way too confident in their assessments given the # of conditions that exist in testing this.

Edited by Alpine Scenery

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Posted (edited)
19 minutes ago, Alpine Scenery said:

I am not sure what you mean by activate the approach?

If you select an approach on a Garmin GPS, you can Load or Load and Activate.

In the real Garmin GPS, activating the approach takes you directly to the IAF, removing all flightplan waypoints before the IAF.

This is NOT related to selecting APR on the autopilot! 🙂

Edited by Bert Pieke

Bert

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Posted (edited)

Right, but some of the planes that support the VGP mode will give you a longer VPATH all the way to the runway way before a 2-4 mile intercept point. If you can keep the VGP on the entire way down, doesn't that mean the RNAV was successful?

You will see the circle and the VSI needle be taken control of by the GPS, the GP will not be indicated at first, it will show VPATH, the VPATH will turn into VGP, then the VGP turns into GP I think (depends on the plane), sometimes it stays at VGP.

If you break the VPATH before it turns into a VGP or GP, you will either see a big line crossing out the PATH or VPATH, or you will see it change mode and show ALT-V or ALT-S, or something like that (again hard to recall).

If a proper RNAV requires waypoint clearance altitudes, that I have no idea as I wasn't paying attention, but it's probably not working like that. It's really hard to remember all these things, because I don't pay attention that closely.

Edited by Alpine Scenery

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9 minutes ago, Alpine Scenery said:

Right, but some of the planes that support the VGP mode will give you a longer VPATH all the way to the runway way before a 2-4 mile intercept point.

WT have been working on the G3000 GPS, and they may well have fixed some things already, which is great!

The G1000 or GNS530 do not have any of this, and clearly expose the underlying problems..


Bert

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I see, I don't know all the different GPS models in each plane. For a non-pilot that doesn't pay attention to that kind of stuff, I'd have to make a mental note to start paying more attention. 

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