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    The Staff of SOH

  • Please see the most recent updates in the "Where did the .com name go?" thread. Posts number 16 and 17.

    Post 16 Update

    Post 17 Warning

PMDG744 FMC Problem/Fix

jimjones

SOH-CM-2023
The FMC in the PMDG 744, which had several times successfully guided the plane in a programmed flight began failing in a number of ways such as thrusting through a set altitude and departing longitudinal courses and creating havoc along the way.

This plane, once thought airworthy and able to use the FMC reliably, continued to be used only periodically to maintain knowlege of its use. New planes such as the P-51, Spifire, B-17 and others interrupted flying the 744.

Recent 744 FMC flights failed. Why? After reloading the 744 with no improvement, recent changes to FSX were considered. Finally, it was determined that changes to the joystick settings to better handle the spitfire were the blame. Reduced null zone values for all three axes allowed the joystick to introduce spurious inputs to the plane, thus the failure for the FMC to control. Simple autopilot problems were also fixed. Maybe this will help others with similar problems.

When confronted with my error the solution was like the joke: I could not understand why the ball kept getting bigger and bigger, until it hit me.
 
Very useful info, Jim. What have you restored the null zone values to ? Is there a minimum you would recommend ?
 
Paul, my null values are about 1/3 from left to right. I did not try other values but these worked well for me. Probably joystick dependent. Mine is a Logitech Extreme 3DPro.

Jim
 
Thanks for that Jim. You've probably saved me and a lot of others some head scratching in the future.
 
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