Having been away from the B747-400 QOTS II for a while, I am now having a problem with the autopilot not working correctly and continually disconnecting.

As an example I have just taken off, climbed manually to 6,000ft and am flying at 250 kts clean. I have VNAV connected and green, together with HDG SEL green, SPD green and FD green indicating. However, when I select any autopilot switch, the switch itself illuminates, but I get an amber horizontal line through the HDG SEL indication on the PFD. The autopilot immediately disconnects with an audible wailer sound.

Similarly, if I route on a planned leg and have LNAV green indicating, the same thing happens again when I try and connect any autopilot.

In another thread I saw a reference to 'Realistic autopilot connection' where the writer solve their problem by disabling this function. Sadly, this did not work for me.
I have tried 'repairing' my installation, and when that didn't work, I did acomplete uninstall/ re-install using the PMDG Installer app. So far without success.

Any constructive help gratefully received.

6 hours ago, roadrabbit149 said:

'Realistic autopilot connection' where the writer solve their problem by disabling this function. Sadly, this did not work for me.
 

If the airplane isn't trimmed correctly, it can cause an automatic pilot disconnect due to improper positioning of the aileron, elevator, and trim tabs. It's also a good idea to check for any spikes in the joystick and consider recalibrating it. Unfortunately, I won't be able to access my computer for a few days. I'm not sure if there are any other settings to consider besides the ones you mentioned, such as turbulence settings.

Edited May 1, 20233 yr by LRBS

Maybe your climb speed is to high. I use a 737 during climb out I set speed as per FMC. When reaching 10,000 ft. it automaticllay increase to 250 kts. and climds at 250 kts.