Autopilot Help Please

Hi,

noted at some aircraft that suddenly during the flight the autopilot adjustments cannot be fine-tuned by clicking on - or + signs. The HDG, NAV and IAS, which can normally be adjusted by a single digit can only be adjusted by ten (-+ sign). The ALT, which can normally be adjusted by 100 ft can only be adjusted by 1000 (-+ sign). For some reason the VSI selection is not effected. This happens during flight, so probably another panel selection causes this. I tried to figure it out to no avail.

Any help in what could be causing this would be appreciated.

Many thanks

Peter

This is caused by a FS9/FSX feature named 'Control Acceleration', but is implemented a bit buggy.

Pete Dowson has made a fix for that in FSUIPC (needs to be registered) and he perfectly explains what happens.

From Pete's FSUIPC User Guide:

QUOTE:

Fix control acceleration is provided to try to fix the occasional stuck control acceleration—i.e. the problem with some

panels where the increments/decrements to values like heading, course, and so on, get stuck at 10 (for instance—

sometimes, for timing reasons, you get rather more unpredictability). These “accelerations” are actually legitimate when a

key or mouse is held down long enough, but it seems some things can make them ‘stick’. What happens is that inside FS

there's a timing check: closely arriving controls trigger the acceleration. The problem appears to be that FS does not care

whether these controls are all the same or all different. The assumption seems to be that, if they are arriving that close then

they MUST be the same—the user couldn't move the mouse to another spot, or select another key on the keyboard, so

quickly. However, some gauges or other driver programs can be sending controls very fast indeed, hence the problem.

The “fix” for this intercepts all controls, and changes the elapsed time check in FS before forwarding every different

control, so that the time elapsed looks large enough. If it sees successive identical controls then it leaves them, so they can

be accelerated as normal.

The end effect of this is likely to be the reverse of the original problem. For normal use of mouse and keyboard there is

normally no difference, but if some gauge or driver starts sending controls very fast (i.e. at less than 400 mSec intervals)

then the controls may not accelerate even when you expect them to. I tend to think this is better though.

Note that this fix is defaulted off. This is because, for those exact same panels it is designed to help, the continuous arrival

of those controls causes keyboard use to never accelerate. Numeric keypad users for throttle, elevator, rudder, aileron and

trim, in particular, may find these controls very unresponsive as a result. If you use a joystick then I recommend enabling

this facility, but otherwise make sure it is off.

END-QUOTE

Without FSUIPC, there's no simple solution.

Rob

Many thanks for the comprehensive answer Rob,

It is only few older aircraft, which are acting up like this. My B707 and A330 in particular. I noted with B707 that this anomaly happens when I move to FO panel to switch the pitot heat on and then back to the cockpit. Also, I noted that when I save the flight (with this problem), close it and re-open the saved flight the problem is gone. In A330 flipping the Barometer switch (Gauge003!Baro) seemed to eliminate this problem. However placing the same switch to B707 did nothing. I will do some more tests before using the FSUIPC option. But it will probably be the only solution. Many thanks again. Peter

Many thanks for the comprehensive answer Rob,

It is only few older aircraft, which are acting up like this. My B707 and A330 in particular. I noted with B707 that this anomaly happens when I move to FO panel to switch the pitot heat on and then back to the cockpit. Also, I noted that when I save the flight (with this problem), close it and re-open the saved flight the problem is gone. In A330 flipping the Barometer switch (Gauge003!Baro) seemed to eliminate this problem. However placing the same switch to B707 did nothing. I will do some more tests before using the FSUIPC option. But it will probably be the only solution. Many thanks again. Peter

You're welcome ;)

Because it IS a timing bug in FS9/FSX, it's kind of unpredictable IF/WHEN is will occur, and when it works normally again. (reloading will always help).

What will surely trigger it, if an ill-designed gauge will fire events continuously. (every 55 msec).

Unfortunately there are still many gauges (or mdl code) around that do this.

Rob