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Unable to follow the route properli in LNAV


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@Hans Hartmann
 

Yes that is what i told in my first post ... there is a striking resemblance in what we show.

 

BUT ... I personally think it is more the tailwind from the lower left that is causing the problem. The wind hitting the plane in a certain angle and the plane can not cope / compute 


Like i said the plane is “struggling” against the wind ... with a slight bank ... and suddenly it crosses a certain stress lvl and it pops to a way more aggressive bank .. and then counter correcting happens .. etc etc .

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2 minutes ago, DGH said:

@Hans Hartmann
 

Yes that is what i told in my first post ... there is a striking resemblance in what we show.

 

BUT ... I personally think it is more the tailwind from the lower left that is causing the problem. The wind hitting the plane in a certain angle and the plane can not cope / compute 


Like i said the plane is “struggling” against the wind ... with a slight bank ... and suddenly it crosses a certain stress lvl and it pops to a way more aggressive bank .. and then counter correcting happens .. etc etc .

The first thing that came to my mind was there might be a problem with the 359 <-> 0 degree "border". And this might be increased by the wind. I will try to reproduce this and then report back.

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48 minutes ago, Hans Hartmann said:

The first thing that came to my mind was there might be a problem with the 359 <-> 0 degree "border". And this might be increased by the wind. I will try to reproduce this and then report back.

Hi Hans

 

thanks for checking. The initial poster was not flying north according his drawing ... but could be. 
 

the think is that the plane was backing slightly ... “against a wall”. That is weird on its own because i do not think an airline is banking to compensate wind. Then suddenly “the wall gave in” 

 

but sure ... the wall could be the “360” 

 

hope you can find something out

thanks for the time

 

 

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2 hours ago, Hans Hartmann said:

@CRJHendy @DGH@Skillizfaction Is it correct that you all were flying pretty much straight north?

Hi @Hans Hartmann!

 

Yes.  Flying north.  Today I am flying westerly and no issues.  Very strange.  Thank you for looking into this.  Also big thanks to you, @Mathijs Kok and the rest of the CRJ team...This is a wonderful addition to MSFS.

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I had this today. It maybe happens once every 8 or so flights for me. However, I enabled HEADING mode to intercept the course line then as I was about to cross it. Enabled NAV mode. Once I did that, the aircraft started tracking fine.

So in my instance the aircraft was banking from one limit to the other trying to get on track so I had to help it because it just couldn't cope. I think it really needed to use a shallower intercept angle.

 

As the dev said, the winds are a sine wave and this is contributing to the issue. That seems correct. However, if we can manually get on track, enable NAV and have it track correctly then the issue would appear to be that the logic used to intercept the heading is not factoring in the winds as well as we might have hoped. 

 

So for any of you that have this issue more than me. Once the issue starts, use heading mode to intercept the track then switch to NAV mode and see what happens. I intercepted the track on maybe a 10% offset and pushed NAV just before it was about to cross it. Obviously you will want to zoom in to the 5km range for this 🙂

 

I had a 30% tailwind blowing at 30kts.

My route was YPKS -> VIRUR -> YSCO

The turn to YSCO would always turn early (I think this might be a known issue) and start the wobble. This one seems to do it pretty reliably for me.

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Except for me, when I enabled NAV again after getting stable and on track with HEADING mode it didn't happen again.

Maybe there is a threshold I was no longer exceeding allowing me to continue without issue.

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Hi Mathijs and Hans, have you been able to replicate and understand the issue?  I'm happy to do some testing if you have certain conditions you would like debugged.  Maybe different weights, CG's, etc. (a small DOE so to speak) would be helpful? I suspect you have many users here ready to help pin down the issue.

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  • Aerosoft

We are trying to find a way to reliably recreate this scenario. So it's definitely on our scope.

It could help if you could post some full flight plans and some basic data of the environment as well (speed, flight level, wind, temperature).

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  • 3 weeks later...

I flew eham-esgg with no problem. But when I fly esms-essa i have this problem to NEXIL hdg 001. After nexil when all is good i fly hdg 017. I have tryed a few times from esms-essa and same s-turns to nexil everytime.

 

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I am experiencing the same issues. When I engage autopilot, the plane wants to fly to my next waypoint in an "S" path. Screenshot below.

 

KCLT/36C-WEAZL4-CLAWD-HVQ-ILS RWY 05-KCRW

 

Live Weather.

 

I attempted this flight twice with the CRJ-700 and had the same results. I switched to the A320 (with Live Weather again) and had no autopilot problems at all. So the idea that it is a Microsoft problem doesn't seem accurate. Other than autopilot issues and remembering not to hit "ESC" key, I am enjoying the CRJ. I do hope this gets resolved.

Microsoft Flight Simulator Screenshot 2021.04.22 - 14.45.46.37.png

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The current release of the CRJ7 appears to have broken the autopilot in several respects.  Flight this afternoon from EGKK to EGJJ, takeoff Rwy08, SID= SAM3P.

 

  • Armed SPEED & LNAV before takeoff.
  • After 1000ft turned AP on. 
  • SID requires left hand turn of approx 180 deg.  But at the turn the aircraft began a right-hand turn in the wrong direction!  Needed to switch to HDG to correct and then set FMS to DIR next waypoint after realigning.
  • Then on final to rwy08 EGJJ, plane would not hold 2000ft, even though ALT was shown as captured, and dropped to 1000ft necessitating adjusting  back to 2000ft but GS would not capture, even though it changed on PDF from armed (white) to active (green).

Think I might try removing it, and reinstalling after the latest 2020 World Update and see if makes any difference.

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17 minutes ago, chrissel said:

I'm not an expert but I don't think that arming speed and lnav before takeoff is right

 

 

You're correct. This isn't the way it is supposed to be done. That said though, that's what I do for every take off. That's because without being able to easily map the autopilot functions to my TCA throttle quadrant I find it a hassle to select the autopilot functions immediately after take off when being quick is more critical. So before take off I select speed mode and heading mode (or nav mode if the departure allows for it) and then once I get to 600 feet I engage the autopilot. Now I can use the buttons I do have mapped to control my speed and heading. Honestly it works like a charm.

 

 

28 minutes ago, STUARTH said:

 

  • SID requires left hand turn of approx 180 deg.  But at the turn the aircraft began a right-hand turn in the wrong direction!  Needed to switch to HDG to correct and then set FMS to DIR next waypoint after realigning.

 

If the turn was indeed close to 180 degrees then that could make sense depending on what direction the aircraft was heading in. The FD will normally turn in the shortest direction to the new heading. There is one exception to this but I don't think it applies to this scenario and I'm not sure if the Aerosoft CRJ is programmed to account for that exception. The exception is that if you, as the pilot, manually turn the heading bug past your 6 o'clock position then the FD will keep the plane turning in the direction it was already turning in. IE, you're heading North and you turn the heading bug to the right to a heading of 180 the plane will start a right turn to 180. If you then turn the knob further right to a heading of say 270, the plane will still keep turning right even though it would now be shorter to turn left. As I said though I don't know if the Aerosoft CRJ acts this way.

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