MSFS M20R "Fishes" right & left continuously along course...

[Truthan 75]

Just wondering if anyone has experienced this issue too... 

When flying either a GPS course or locked onto an ILS approach, the M20R gradually drifts off course to one side or the other, then banks about 15 degrees to correct, and OVERFLIES the course to the other side, then back again, continuously, in a zig-zag motion. The time between "left of course" and "right of course" corrections seems to be about a minute or so. It's especially a bummer flying an ILS approach in poor visibility, for the aircraft position to the left or right of the threshold can be dozens to hundreds of meters when nearing the runway. She flies strait and steady when in HDG mode.

It's as if the avionics are set to check course every minute or so rather than continuous tracking every few seconds. Anyone else experience this yet? Any idea how to remedy it? I haven't had time to peruse the root files yet, but maybe a "check_course_every_XX_seconds" entry in a CFG file or something?

Great aircraft though. Loving it otherwise!

[wwdavis 44]

I look at my plane from behind in the the chase mode. I can see the rudder quickly zig-zagging back and forth left and right. I look from the cockpit view the nose swings quickly zig-zagging left and right.  Irritating !!

Even FSUIPC7 calibration  and slope adjustment won't take it out

 

Bill Davis

[Truthan 75]

Rudder is stable for me. My "fishing' issue seems to involve minute long lags in the continuous tracking of the course. It's as if the GPS can only follow courses at 10 degree increments or something, so for instance any course that falls in between, like say 354 degrees, causes the aircraft to toggle course between 350 and 360 for calculated periods that can average a 354 course. Some users have complained that after a few minutes in the air, they can only tune their NAV and HDG radials in 10 degree increments too... hmmm...I wonder if the problems are related to the same underlying issue?

[Bert Pieke 7,585]

1 hour ago, Truthan said:

Just wondering if anyone has experienced this issue too... 

When flying either a GPS course or locked onto an ILS approach, the M20R gradually drifts off course to one side or the other, then banks about 15 degrees to correct, and OVERFLIES the course to the other side, then back again, continuously, in a zig-zag motion.

 

There is a long discussion on this, and yes, others are seeing this too.

Carenado is currently "looking into it"...

A user found a workaround:  When the autopilot is zig zagging plus minus 10 degrees in GPS NAV mode, watch the CDI (on the GNS530) and as it passes through the mid-point, switch NAV off and back on on the autopilot.

[Truthan 75]

Thanks Bert, I looked around the web but must have missed that conversation... I'm at work now but will try that fix later. Can live with the issue for now so long as that single click does the trick!

[Bert Pieke 7,585]

5 minutes ago, Truthan said:

Thanks Bert, I looked around the web but must have missed that conversation... I'm at work now but will try that fix later. Can live with the issue for now so long as that single click does the trick!

Sorry to disappoint you, but it is actually two clicks 😉

 

page 19 and following

Edited September 21, 2020 by Bert Pieke

[Truthan 75]

20 hours ago, Bert Pieke said:

A user found a workaround:  When the autopilot is zig zagging plus minus 10 degrees in GPS NAV mode, watch the CDI (on the GNS530) and as it passes through the mid-point, switch NAV off and back on on the autopilot.

OK, I can confirm that this work-around fix works (for my rig at least). Toggling either the NAV or APR buttons (for GPS course or ILS post-capture, respectively) does the trick.

For accuracy, setting the CDI needle via the OBS knob on the heading indicator to the intended course and making the (NAV or APR) button toggle when it is not only "needle aligned" but also centered strait up is helpful. To be sure, I toggled and re-toggled the respective AP buttons an additional once or twice to assure that the aircraft was locked solid on course, and once stabilized, it held it nicely. On ILS approach the glideslope was caught properly too, and all was good for a rock solid approach. As the aircraft judders a bit when buttons are pressed or depressed, and you can easily lose mouse focus on the intended button as the CDI swings to center, it's best to use the keyboard shortcuts for the toggles though... NAV = CTRL + N and APR = CTRL + A.

I didn't have the time to test if the course holds solid after a waypoint turn however, but I'll try that tonight after work.

[Bert Pieke 7,585]

10 minutes ago, Truthan said:

I didn't have the time to test if the course holds solid after a waypoint turn however, but I'll try that tonight after work.

I found that it may lose its fine motor control after a turn, and you have to re-apply the fix. 🙂

[FreedFlyer97231 10]

Experienced this issue today as well. Setting course towards a VOR, the AP hunts for the course. Banks left, levels out.... banks right, levels out... etc. Always overshooting, it seems.

[Truthan 75]

9 hours ago, FreedFlyer97231 said:

Experienced this issue today as well. Setting course towards a VOR, the AP hunts for the course. Banks left, levels out.... banks right, levels out... etc. Always overshooting, it seems.

Yeah, it's a frustrating issue, as the aircraft is pretty sweet otherwise. Hope this gets fixed....
To be sure, even though the toggling of the NAV button does the trick and having the course deviation needle set to the course helps to know WHEN to toggle, it’s still frustrating as it takes several attempts to get it just right, as the plane continues to slightly overshooting the course again and again till it settles down, etc.

I've found this to be somewhat faster and more expedient work around:

1. Let the plane settle into its usual zig-zag.

2. Open the VFR MAP window (with the “V” key), and make sure the "GPS" tracking button is set to ON.

3. Zoom ALL THE WAY IN on the map with your mouse wheel, as far as the zoom will allow.

4. When the aircraft is on the "inbound" leg of the zig-zag, and about ONE PLANE WIDTH from the course (as illustrated in the picture below), quickly toggle the CDI button on the GNS 530 from GPS to VLOC and then BACK TO GPS as quickly as possible (i.e. two clicks).

Doing so, the aircraft will still overshoot the course line, but only by just a little, reducing the "angle of zig-zag" to a degree or so, rather than ten. When the aircraft icon crosses back onto the course line in a few seconds, toggle the CDI button again. You should now be very close to right on course and steady. You can of course rinse and repeat this a few times to really lock it down, for with each toggle the “angle of zig-zag” is further reduced.

Thanks to the zoomed in accuracy of the VFR map, I found this to be simple and effective with minimal frustration and takes just a few seconds. I assume the same effect would work for an ILS approach, but of course you'd be toggling from VLOC to GPS, rather the other way around.

Hope the issue gets patched. I really love the aircraft otherwise. In the screenshot below I added the green line to illustrate the aircraft's "inbound leg" of the zig-zag...

 

Edited September 24, 2020 by Truthan
typo, verbiage

[Truthan 75]

FYI to anyone following this thread, Carenado has released a patch for the M20R (and the C182) that fixes the Zig-Zag NAV and APR issue. If you purchased through the MSFS Marketplace, go to your Content Manager, search for "Carenado" and download the update. She holds rock solid on course now. This Post has more user comments about it.