Jump to content

RNAV Approaches


David Spaulding

Recommended Posts

David Spaulding

Not sure if this is just a random fluke, but I just did the RNAV 28R to KSFO.  Inside the FAF, the jet started doing this wing flapping like quick oscillation.  Is this because FSL Airbus isn't complete with shooting these approaches, or was it something I did or PC related?  Anyone else have this happen?  Thanks.

 

Edit:  Forgive me, it was in the A321 as well.  Doh.

 

GRRR!!  And AP was off.

Link to post
Markus Burkhard
4 hours ago, Koen Meier said:

Fslabs bus isn’t RNP AR certified.

That's correct, but not all RNAV approaches into KSFO are RNP AR. So we need to know which one was flown in this case. In any case, it shouldn't oscillate flying any of these.

Link to post
Koen Meier
1 minute ago, Markus Burkhard said:

That's correct, but not all RNAV approaches into KSFO are RNP AR. So we need to know which one was flown in this case. In any case, it shouldn't oscillate flying any of these.

of course. the straight in rnp should be an issue ofcourse.

Link to post
Stu Antonio
8 hours ago, David Spaulding said:

And AP was off.

Wait, you had "wing flapping" with autopilot off? 

Link to post
David Spaulding

Affirmative.  Also it was the RNAV28R Z approach.  I did forget to select APPR once cleared for the approach, but remembered just before the AXMUL, was fully configured prior and stable.  So I got FINAL APP on FMA, clicked AP off, and pushed the nose down to about 3 degrees NU.  About a mile from threshold it did about 3 seconds of the wiggle, went away, then did 2 seconds of the wiggle, went away.  Landed.  I don't remember FPS being really low, it may have dipped a little, due to the LOD increasing?  But I can't for sure say my FPS got below 20, I don't think it did.

 

 

Link to post
Markus Burkhard

The RNAV Z for RWY28R is not RNP AR and therefore one that should work perfectly fine. 

Having said that, the issue you describe can't possibly be connected to the approach procedure you're flying, since the AP is switched OFF. So something else must be causing this.
Are you able to reproduce the mentioned issue at will?

Link to post
Yang Shuo

The 151 version has lost the function of the FINAL APP, this is an obvious BUG, how can it be "work perfectly fine" ?

Link to post
David Spaulding
19 hours ago, Markus Burkhard said:

The RNAV Z for RWY28R is not RNP AR and therefore one that should work perfectly fine. 

Having said that, the issue you describe can't possibly be connected to the approach procedure you're flying, since the AP is switched OFF. So something else must be causing this.
Are you able to reproduce the mentioned issue at will?

Hey Markus,

 

I haven't tried to reproduce yet.  This was the one time it has happened to me, hence the question if anyone else experience what I did.  I'll see if I can.  I also use Activesky real weather, and GSX if that matters.  Not sure if maybe a certain wind phenomena may have triggered it?  Anyways, if it does it again, then its highly likely its not weather related.

Edit:

I just did another attempt, and nothing out of the ordinary occurred regarding oscillations.  I didn't really recreate every single detail that happened, so maybe it was FPS related?  When it happened, it was clear skies, about 20 knots of headwind, at night, with AI traffic, default airport with GSX assets.  Hence, the airport was lit up, which does impact a bit on performance, CPU wise.  I just did the same thing, in the daylight with plenty of menacing AI traffic. (especially one Piper Warrior on final to 28R)  IDK.  When it happened, it didn't really seem like performance was dipping extremely low.  Oh I did remember to press the APPR button, and didn't get FINAL APP right away, but it did appear sometime before AXMUL, maybe the fix before that.

 

Oh I just realized I have .126 installed.  Would that maybe be why it happened?

Link to post
Tim Smith
9 hours ago, Yang Shuo said:

The 151 version has lost the function of the FINAL APP, this is an obvious BUG, how can it be "work perfectly fine" ?

I’ve done plenty of RNAV approaches in the last week with no apparent issues 

Link to post
David Spaulding

Just did another attempt.  I updated to .151 at night, close to same landing weight, close to same wx conditions.  Same as before. This time I noticed it did a very brief wiggle (half second and AP off) right when the LOD was increasing, which tells me it sounds more like a performance issue with my machine.  I guess it just takes a micro hang to really cause the FBW to start this behavior.  I thought I was getting decent frames all the way down too.  Huh.

Also, again, didn't get FINAL APP until about 15 mile final.  Even though I selected APPR after confirming approach phase and intercepting the vertical path, it refused to switch to FINAL APP until much later especially while on the transition.  I don't recall a distance parameter for switching to FINAL APP.  We have always been able to get it immediately when the jet knows its on both the vertical path and horizontal path of the approach with approach phase active.  Oh well.

Link to post
Koen Meier

you only should select the app button once inbound for the final appraoch fix as arming it before will mess with descent.

Link to post
David Spaulding

I was “inbound”. Also, what? Never heard that limitation before.

I was established and tracking the RNAV track and approached the V path from below, just like an ILS (even though that still isn’t an exact requirement), there was no reason for FINAL APP to not immediately appear.

The only example that when pushing APPR and not getting FINAL APP immediately is the aircraft is being flown using HDG and is currently located off track.

Sent from my iPhone using Tapatalk Pro

Link to post
Koen Meier
8 minutes ago, David Spaulding said:

I was “inbound”. Also, what? Never heard that limitation before.

I was established and tracking the RNAV track and approached the V path from below, just like an ILS (even though that still isn’t an exact requirement), there was no reason for FINAL APP to not immediately appear.


Sent from my iPhone using Tapatalk Pro

AXMUL is the final approach fix for the procedure denoted in navigraph as a star. with RNPA AR procedures activating the APP mode before being inbound to the final approach fix will result in different descent management. it isnt really a limitation but it helps you with your descent management during the approach phase.

Link to post
David Spaulding

But that still doesn’t matter. The jet knows it’s on the correct path. I activated approach phase before the transition and selected APPR just after. I was tracking both V/DEV and L/DEV precisely. There is no reason for FINAL APP to not show. I’ve done this before in the real jet numerous times. It’s not right.

Here’s my materials. Directly from the QRH.




Sent from my iPhone using Tapatalk Pro

Edited by Norman Blackburn
Removed copyright material
Link to post
David Spaulding

Also:


(From systems manuals)

It doesn’t mention anything about a distance prior to FAF. This is not implemented correctly.


Sent from my iPhone using Tapatalk Pro

Edited by Norman Blackburn
Removed copyright material
Link to post
Koen Meier

that image will be removed ue to copyright as fslabs is rather strict on the information that the associated manuals contains.

images from the sim would help cause then we can see the ND and PFD.

Link to post
David Spaulding

Okay, but my point still stands. It’s incorrect.


Sent from my iPhone using Tapatalk Pro

Link to post
Yang Shuo
On 4/29/2021 at 9:53 PM, David Spaulding said:

Okay, but my point still stands. It’s incorrect.


Sent from my iPhone using Tapatalk Pro

There is indeed a big problem with the auto flight logic, and a lot of other content will be implicated if the bug is fixed.

  • Like 1
Link to post
×
×
  • Create New...