Anyone else have this problem? I am using the Carenado PC-12 with the F1 GTN 750 installed. Except in a RNAV approach, the AP has a difficult time tracking the course when turning from one waypoint to the next if the turn is more than like 10 degrees to the left or right. It either begins the turn too late, or doesn't command a steep enough bank, or a combination of both. Then it will start doing S turns, trying to capture the magenta line, often failing completely to ever get back on course. I do not have "half bank" selected. Once on an RNAV approach, it seems to follow the course accurately. I've noticed the same behavior in other GTN 750 equipped aircraft, but it seems to be more pronounced in the PC-12.

I used the F1 GTN 750 in several aircraft for over three years and never experienced anything like that. I recently moved on the the Reality XP GTN 750 due to a new rich feature set, but the F1 GTN was always accurate and reliable in performance. You must have some other issues at play.

12 hours ago, TedK said:

Anyone else have this problem? I am using the Carenado PC-12 with the F1 GTN 750 installed. Except in a RNAV approach, the AP has a difficult time tracking the course when turning from one waypoint to the next if the turn is more than like 10 degrees to the left or right. It either begins the turn too late, or doesn't command a steep enough bank, or a combination of both. Then it will start doing S turns, trying to capture the magenta line, often failing completely to ever get back on course. I do not have "half bank" selected. Once on an RNAV approach, it seems to follow the course accurately. I've noticed the same behavior in other GTN 750 equipped aircraft, but it seems to be more pronounced in the PC-12.

Hi Folks,

My experience reflects Frank's...

I believe the GTN has an option on how it handles waypoints - forcing it to cross over a waypoint before starting a turn - instead of cutting corners - maybe research that (not sure where it is off the top of my head) ?

Are you running Bert's panel mod v57 - I believe he worked many issues with this aircraft including the autopilot... If not - just PM Bert your email address and kindly request it... It's a "must have"...

Regards,
Scott

 

I've been able to replicate odd tracking issues in a variety of conditions but the most egregious are:

• Extreme crosswinds at cruise
• Transitioning from VLOC to GPS (or vice versa)
• Any time acceleration above 2x

I've been able to replicate all three issues with and without Bert's mods as well as the Flight1 GTN 750 and 650.

So... the good news:

• It's not the Flight1 GTN
• It's not Bert's mods

But... the bad news:

• Bert's mods won't fix it
• It's probably the AP logic, which I understand Carenado to use the default FSX/P3D AP engine/logic.

I've replicated my "test" routes with the Flight1 King Air 200, Cessna Mustang, Aerosoft Twin Otter and the RealAir Turbine Duke and none of them suffer from the tracking issue. Although only the Twotter and Duke were tested with and without the Flight1 GTNs.

I have had these problems with a couple of aircraft including PC-12 and Seminole. There is a bit of a bug there somewhere. Based on experience as well as a couple of PM's with Bert, I suspect it is the autopilot causing some problems. Carenado seems to have a program which puts a few bugs into each release. They never want to have a model out there that is bug free because they know we will then expect that all the time. They are making too much money on sub par releases and want to keep it that way! If that sounds negative then so sorry. You can make me positive when you find one of their models that is bug free. Look how many releases they have. Hard to believe that many releases and updates and they have never screwed up and got it right. Even Chimps learn faster from their mistakes.

I personally have done dozens of flights with the PC-12 and the GTN750 and have never experienced any of the problems described above. I do make a happen of having the heading bug in sync with the heading the autopilot is using to track the GPS course. Whether that helps enroute, I don’t know. It definitely makes a difference tracking the final approach course. Also, the PC-12 is very picky about proper speed when tracking a glide slope. I am employing all of Bert’s mods. 

This poor tracking issue appears in any GTN750 equipped aircraft I have, including the A2A C182. I downloaded Bert's (and other's) mods for the PC-12. Happy with the CDI deflection fix, but not happy with the default GPS screen: Could no longer disable MSG notifications by holding MSG button. The weather radar no longer worked. And I was getting unrealistic NP% readings. The real PC-12 with PT6 will go over 100%. The PC-12 with the mods would not. Uninstalled the mods and rather just put up with the bad CDI with no left deflection. Also, I saw no difference in the poor tracking with the mods installed.

On 2/6/2018 at 2:30 PM, TedK said:

This poor tracking issue appears in any GTN750 equipped aircraft I have, including the A2A C182. I downloaded Bert's (and other's) mods for the PC-12. Happy with the CDI deflection fix, but not happy with the default GPS screen: Could no longer disable MSG notifications by holding MSG button. The weather radar no longer worked. And I was getting unrealistic NP% readings. The real PC-12 with PT6 will go over 100%. The PC-12 with the mods would not. Uninstalled the mods and rather just put up with the bad CDI with no left deflection. Also, I saw no difference in the poor tracking with the mods installed.

It does not take a lot of panel.cfg editing to restore the original (broken) Carenado GNS, and the Avidyne which I disabled for performance reasons..

The MSG notifications are turned off as default.. I like it better that way..

As for the engine performance, that is Autogyro's work.. most think it is an improvement..

Up to you what you prefer, but you CAN mix and match..

As a follow-up on this unresolved issue I can report that the poor tracking is related directly to, or coincidental to, lower frame rates. If I turn off the weather engine (eliminating clouds and winds aloft) the GTN 750 tracks fairly well, although not perfectly. It seems to be highly dependent on processor performance (totally unlike the Flight1 G1000 installed in the B200 King Air and C510 Mustang, which perform perfectly at any frame rate). On my PC the GTN 750 is useless when the frame rates fall below 30 fps. Seems ridiculous that I will have to go out and buy a PC with a Freon-cooled mega processor just to be able to run all my add-ons at one time.

BTW, responding to reported issues by saying, "I've never experienced this issue" is totally useless information when the idea of reporting the issue is to find people who HAVE experienced it and have possibly found a fix. It just seems like a way of saying, "You're not holding it right."   Just saying.

1 hour ago, TedK said:

As a follow-up on this unresolved issue I can report that the poor tracking is related directly to, or coincidental to, lower frame rates. If I turn off the weather engine (eliminating clouds and winds aloft) the GTN 750 tracks fairly well, although not perfectly. It seems to be highly dependent on processor performance (totally unlike the Flight1 G1000 installed in the B200 King Air and C510 Mustang, which perform perfectly at any frame rate). On my PC the GTN 750 is useless when the frame rates fall below 30 fps. Seems ridiculous that I will have to go out and buy a PC with a Freon-cooled mega processor just to be able to run all my add-ons at one time.

BTW, responding to reported issues by saying, "I've never experienced this issue" is totally useless information when the idea of reporting the issue is to find people who HAVE experienced it and have possibly found a fix. It just seems like a way of saying, "You're not holding it right."   Just saying.

What CPU core have you got the GTN set to?

I have found that it performs better when it is assigned to a low use core..

On 10/2/2018 at 12:07 PM, Bert Pieke said:

What CPU core have you got the GTN set to?

I have found that it performs better when it is assigned to a low use core..

I've experimented but I think the last setting was ALL. I don't really know what a low use core is, but it has AUTO then 1 through 7 (?) and ALL. Are you saying a low number like 1 or 2? BTW Thanks for your response.

23 minutes ago, TedK said:

I've experimented but I think the last setting was ALL. I don't really know what a low use core is, but it has AUTO then 1 through 7 (?) and ALL. Are you saying a low number like 1 or 2? BTW Thanks for your response.

Try running the Windows Task Manager and P3D concurrently... In the performance tab, you can see the real time usage of each CPU core.  When the CPU is heavily loaded, observe the individual cores and see which core(s) are not maxed out...

On 10/10/2018 at 12:23 PM, Bert Pieke said:

Try running the Windows Task Manager and P3D concurrently... In the performance tab, you can see the real time usage of each CPU core.  When the CPU is heavily loaded, observe the individual cores and see which core(s) are not maxed out...

Hi Bert, interesting topic. Love to know the code used to place the GTN750 on a specific core. Is this then placed in the panel.cfg? Cheers Anton

30 minutes ago, antonvs said:

Hi Bert, interesting topic. Love to know the code used to place the GTN750 on a specific core. Is this then placed in the panel.cfg? Cheers Anton

That is what the CPU Core=XX line is for in the F1GTN.ini file.

Ok, thanks Bert, seems simple and probably of great benefit to using the GTN gauge (regardless of the plane it is used in). I will try this for sure.