Aircraft wobbles when altitude hold is on and simulation rate is 8X or 16X

[BOSS]

Hello everyone. Well, the title pretty much says it all. When I have the autopilot to hold the altitude and increase the simulation rate to at least 8X the aircraft goes up and down all the time. This is very disturbing, especially when I fly IFR because I get alerts from ATC all the time to correct my altitude. Does anybody else experience the same problem?

[pirateinparadise]

It is not a problem. The barometric pressure is changing as the airplane flies through different areas. If you were flying at regular time speed, ATC would be constantly providing you the new altimeter setting every time you talk to them.

[BOSS]

This also happens at altitudes over FL180 at cruise speed. Also when the skies are clear.

[De Kaashaas]

The autopilot corrects your altitude and attitude on a constant basis. For example: when your set altitude is set to FL320 and your altitude is 320002, the a/p will correct this by a very slow descent. It will than calculate when to stop this descent but it rarely has it spot on. So then when it's 31998, it will start a very slow climb etc. When on a simrate of x1, you probably won't even notice thus.

By accelarating the simulation rate this effect will cause the aircraft to 'wobble' since the intervals are bigger. The a/p will notice a bigger difference in altitude compared to what it's supposed to be / has predicted and will react with a more drastic climb or descent.

When accelarating the simrate when a set altitude isn't reached it may very well osscilate out of control even.

The solution: don't accelarate the simrate, ór reduce the acceleration rate. But in any case, prevent accelerating the simrate when a vertical speed change is imminent (i.e.: before a climb or descent and before a climd or descent is being de/accelarated.

[BOSS]

I think it is the steam version bug. I own all FS from 2000 up to FS Deluxe and this was not an issue.

It IS useful to accelerate the simrate when I do long haul flights.

After doing some research, I found out that many users have the same issue as me. I paste here some examples from other forums:

https://steamcommunity.com/app/314160/discussions/1/612823460261534110/

http://www.flightsim.com/vbfs/showthread.php?250822-Acceleration-seems-to-cause-bobbing-at-8x-amp-16x-time-speed

http://www.avsim.com/topic/63846-acceleration-autopilot-problem/

http://www.airliners.net/forum/viewtopic.php?t=817905

http://www.flightsim.com/vbfs/showthread.php?248903-FSX-Pitches-Up-and-Down-Violently-When-Using-Sim-Rate

http://www.airline-empires.com/index.php?/topic/22478-fsx-autopilot-oscillation/

[Lord Erich]

This has been an issue with FSX: Acceleration as long as it has been out. I personally uninstalled Acceleration with the box version and never had this problem. The problem only happens with the expansion installed. I tested it with the default 737-800. Ran a flight from ORD-EWR 16x speed with no issues even with ASNext installed. Same flight with Acceleration, the plane can't even fly at 16x speed due to the oscillation. I've read multiple post on this and I alway see the same response "don't use 16x speed". I guess for myself and others, this wasn't a problem for us untill the installation of Acceleration. So, you can see why we want it fixed when we were all doing long haul flgiths at 16x speed and now it is impossible to do. I also own Prepar3d and do not have this problem running at 16x speed. This is a bug in Acceleration.

[Lord Erich]

For those out there that have this issue: I sent a support request to Dovetail and this is the response.

Dear xxxxx,

We are sorry that you are experiencing this issue. The development team is aware of this problem, so please look out for a potential update in the future. We apologise for the inconvenience this may have caused you.
If you have any other questions or queries please do not hesitate to contact us again and we shall try our best to help you.




I'm happy that Dovetail is working to fix this for us. It's great to have support for this game again.

[Mr Lispy]

sounds like the same generic email i got from Microsoft when i complained about other issues, never saw an update for years.

[stmccarron]

Have found a possible work around at least an easy one. This seems to occur at any attitude over 17000 so flying at any flight levels the oscilation begins. My assumption from this is when standard pressure is entered and acual ground level pressure is different the program tries to adjust. So until support can look at the programing, fly at 17000 or less...yep gas milage sucks but beats getting dizzy!

[Tsarcasm]

never understood why people use the simulation rate. if you don't have time to do a flight, don't do it. time acceleration is pointless and takes the fun and realistic aspect away.

[Erazer]

I never go above x4 as it causes problems with the response rate of the autopilot and GPS.

The simulator generally won't let you go any higher than x16.

If you go out, or retire to sleep, you'll find the aircraft circling above the destination when you get back to it.