AUTOPILOT DISC message when established on ILS

[Richard McDonald Woods 168]

Repeat tests of landing at MRLB Liberia, Costa Rica with Orbx free scenery, I establish normally on runway 07, with the LOC and glideslope showing captured. But then halfway during the descent, the red AUTOPILOT DISC message occurs and the wailer sounds. Why?

I can see no contraindications, but see no way to overcome. Help much appreciated.😉

[scandinavian13 5,192]

1 hour ago, Richard McDonald Woods said:

But then halfway during the descent

I'm guessing you mean that "at some point on the approach," and in that case, a specific fix reference would be helpful. Otherwise "halfway during the descent" could mean something as high as 19000'ish...

1 hour ago, Richard McDonald Woods said:

the red AUTOPILOT DISC message occurs and the wailer sounds. Why?

Technically?

Because the AP got kicked off.

Situationally?

Likely a hardware spike or a trim axis that hasn't been nulled. I'm willing to bet that you might have a flap up/down toggle, and a landing gear toggle, and it happens near your actioning of one of those two commands on the hardware.

In any case, we need a lot more information here. I know you can probably walk through all of this in your head, but we have no visibility to any of that. Be as exhaustively specific as possible.

[Richard McDonald Woods 168]

Hi Kyle,

The video of the approach to runway 07 at MRLB Liberia, Costa Rica is shown below at 27.00: 

Any additional info, please do ask.

Regards, Richard

 

[scandinavian13 5,192]

24 minutes ago, Richard McDonald Woods said:

The video of the approach to runway 07 at MRLB Liberia, Costa Rica is shown below at 27.00: 

This is all well and good, and I see that the AP kicks off, but I did reference a few things that I cannot see in the video...namely things hardware related that would be good to have confirmed. If you need further clarification, let me know.

Either way, something is kicking your AP off, and I can't immediately leap to the conclusion that the aircraft is just suddenly misbehaving for some reason.

[skelsey 765]

Looks to me like some form of rudder trim/rudder input issue.

A sideslip starts steadily increasing up to the point at which the A/P throws up its hands and says "enough of this".

Checked the rudder trim/any control assignments which might be causing the rudder trim to actuate and/or the rudder to deflect?

[Ephedrin 418]

starting at 27:33 there are some SEVERE yaw movements... where do they come from?? 

 

[harvester21 34]

It has to be a rudder input issue, the crab on the approach is not normal, as there is no wind indicated on final approach, and when there was it was only 6 knots and also then there was excessive crabbing going on. Have a look at your rudder trim, is it centered?

[Richard McDonald Woods 168]

Hi Carmen,

Many thanks for your comments under the video! Also thanks to the above for their input.

Up to 27:00, everything is going well and I am established on the ILS. Yet shortly after, without my input, the aircraft suddenly pulls to the left and disaster looms.

I am confused by what is happening.

Regards, R

[scandinavian13 5,192]

13 minutes ago, Richard McDonald Woods said:

Yet shortly after, without my input, the aircraft suddenly pulls to the left and disaster looms.

Definitely going to point back to the hardware issue or FSUIPC misconfig.

Additional issues could be ASN (unlikely, due to the single-axis interference), or EZDOK (less likely - their interference usually isn't limited to the yaw axis as shown in the video).

 

I'd test by removing all rudder axes temporarily (or, perhaps easier - if you have rudder pedals - unplug them for a test).

[Ephedrin 418]

Also make sure that there is no other controller connected to you computer that you don‘t need. FSX and P3D use to assign axes to all hardware axes it can find, even virtual axes like your mouse might have. Go through the controls and check that there isn‘t anything assigned to the rudder and /or rudder trim. 

[pete_auau 1,158]

does it happen  at the  same  point   all the  time  if  it  does  than most likely  its  scenery  issues

[30K 72]

I'm wondering about this massive HDG to TRK difference on the ND with no wind indication. He is somewhat aligned with the runway but look at the ND - the difference is 10°. At around 25 min you see that there is a 5 kt wind but this would never result in a 10° difference. 

[Richard McDonald Woods 168]

Gentlemen,

After further testing, I am none the wiser. Thanks for the suggestions.

• Removed the Orbx scenery from the scenery library but this changed nothing.
• Unticked the FTX>FTXG>AIRPORTS> scenery.BGLs but this changed nothing.
• Unplugged the USB pedals but this changed nothing.
• Decided to continue my itinerary by flying KGSO to MUVR. Approach and landing worked normally.

So I can only conclude that there must be something amiss with the KGSO 23L ILS.

I have been flying into the Orbx freeware airports in North America only as a test of their quality, whilst I wait for an updated B777 or the new B748, and other goodies to come. As I shall not be flying into this airfield for the foreseeable future, I shall leave the problem as closed.

Again, many thanks for the thoughtful help from each of you.

Kind regards, Richard

[harvester21 34]

Hi Richard,

I find it unlikely that the ILS would make your aircraft fly with such a huge crab. Did you check your rudder trim like I suggested?

[scandinavian13 5,192]

4 hours ago, Richard McDonald Woods said:

After further testing, I am none the wiser. Thanks for the suggestions.

• Removed the Orbx scenery from the scenery library but this changed nothing.
• Unticked the FTX>FTXG>AIRPORTS> scenery.BGLs but this changed nothing.
• Unplugged the USB pedals but this changed nothing.
• Decided to continue my itinerary by flying KGSO to MUVR. Approach and landing worked normally.

So I can only conclude that there must be something amiss with the KGSO 23L ILS.

I have been flying into the Orbx freeware airports in North America only as a test of their quality, whilst I wait for an updated B777 or the new B748, and other goodies to come. As I shall not be flying into this airfield for the foreseeable future, I shall leave the problem as closed.

A lot of the things you tried seemingly ignore the real symptoms, though.

The plane is wildly whipping back and forth. This is only caused by: hardware, alterations to sim physics, weather add-ons, or (least likely in this case) the plane.

If unplugging the pedals didn't do anything, I'd search for a rogue axis assignment that might have been picked up by a new USB device the sim decided to assign something to (my mouse has, for example, been picked up as one, due to its extra buttons; my USB PTT has, as well). Additionally, check for weather add-on, settings, FSUIPC assignments/calibrations, or something like EZDOK's camera shake function still being on.