Autopilot turn opposite direction

For years I have noticed that when I initially click the Auto Heading Hold on the stock autopilot the aircraft turns the opposite direction needed for the turn about 3 degrees and bank angle of about 3 degrees. After four seconds or so it then does turn to the desired direction and completes the turn to the desired heading. Other heading changes using the autopilot heading hold function during the session work as they should. I see this in both my P3DV4 and FSXA simulators. As best I remember same was true in FS2004 also, It use to be just an annoyance but now that I am developing a automated precision ILS system where I use the heading hold function for glidepath guidance it has become very concerning.

Has anyone know of a way to overcome this fault in the autopilot? Is there a better autopilot available?

Yes, Bill,
that made me also crazy!!
I send you my AP_Ctrl.xml.

From line 145 to 270 there you will find a solution. Fare away from being perfect, but much better then MS!


Wow!!! That certainly fixed the problem. I use Karol's F111 Autopilot because of the Terrain Following capability built into to it. We use it for our low altitude flying and bombing in the BNS system we worked together on. I will send him a copy of the modified autopilot. I am sure he will appreciate it.

Is there anything else in your AP_Ctrl that I should consider using? I just added the lines of code you mentioned.

Thanks so much,

Hi there. I am another one who is interested in getting an auto-ILS version working, based on Karol's fabulous AILA gauge.

I guess my aim is slightly different because I am trying to hitch it up with a voice assisted module issuing vocal GCA-type instructions. Unlike, I understand, your version, it will be largely aircraft-specific.

As you will probably know if you have followed the original thread over at, where Karol presented AILA, the FSX gauge analyzer throws up a few errors. I managed to get rid of most of them (and they were trivial anyway) , but there is one that presents an issue which I am at a loss at how to resolve. It is line 2553 reading

What, if anything is wrong with that?
Would be happy to provide a copy of my application. I will also have to provide you a new copy of Karol's gauge because I had to make some minor edits there to get it work with my application. Actually the auto-ILS is not aircraft specific. I run it in a minipanel system that will work with any aircraft in your simulator.

I developed it on P3D but it works fine with FSXA on my system. Another simmer testing for me has run into some unusual issues on his FSX simulator that I can not duplicate. So the more folks that test for me would certainly be appreciated.

As far as the Terrain Shadow error I have no idea what would cause that to show as an error.



Resource contributor
From my recollection the "turn" you refer to is is deflection correlation. This is the GP checking alignment is accurate as in real life the Ac will NOT follow a absolute altitude or direction due to the array of environmental forces at play at anyone time. The moving off the "straight line" allows the the instrument conditions to be met i.e checking its actually following a track line, accounting for windirection, drift etc. As an example a pilot following a VOR signal will deviate at least 3 to 5 degrees manually based on the same "line". Even the best GPs drivers have to have a tolerance established - As the creator of Quality Management (W. Edwards Deming ) stated NOTHING is 100% - 99% is about as perfect as you can.
....... the FSX gauge analyzer throws up a few errors. I managed to get rid of most of them (and they were trivial anyway) , but there is one that presents an issue which I am at a loss at how to resolve. It is line 2553 reading

What, if anything is wrong with that?
Try replacing " True " with " 1 " .

It might be something as simple as " the FSX gauge analyzer " prefers the use of 0 and 1 rather than False and True .
Test to see if using " 1 " rids you of the error indication .

Hi Karol, good to have your continued support on this. It is great fun working with AILA.

Indeed, replacing True by 1 does the trick!! Love it, the gauge analyzer now gives a clean bill of health.

In addition to the GCA talkdown I am now also planning a voice-assisted Approach Control Service that guides an aircraft flying in the general direction of the destination airport to a suitable Intercept location at the correct altitude. In that context, is there any way to get at the Tower or Ground Control frequency of an airport? It would be nice if the controller could be heard to say "Contact ground/tower on ...". Here is a pic:

Bill, Edi: yes the initial heading wobble is awkward, having a cure for that would be great.

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Your GCA talkdown sound very intriguing.

The heading wobble fix provided by Edi is awesome. I use Karol's version of the Microsoft Autopilot and would be happy to share with you if you want to try it.

Have asked Edi for the heading lock wobble fix, but generally I shy away from wholly replacing the default AP stuff. Gotta admit that I am not a very good test pilot either, so wouldn't be of much use to you.