First post so be gentle :( FSX with PMDG 747-400When I get to my assigned altitude it is very difficult to hold that altitude with autopilot or not. Gradually climbs untill ATC tell me I'm 300 above and to descend. Descends very slowly and then tries to level out but then slowly climbs again. Not sure if it's a thermal effect? I'm new at this so I'm not sure if it's a bug or not. I use a CH yoke and calibrates ok and I use REX 2.0 weather enigne. Any ideas?

First post so be gentle :( FSX with PMDG 747-400When I get to my assigned altitude it is very difficult to hold that altitude with autopilot or not. Gradually climbs untill ATC tell me I'm 300 above and to descend. Descends very slowly and then tries to level out but then slowly climbs again. Not sure if it's a thermal effect? I'm new at this so I'm not sure if it's a bug or not. I use a CH yoke and calibrates ok and I use REX 2.0 weather enigne. Any ideas?

Did you reset your altimeter at 18,000 (usually with the B key) including the one on the panel?Best regards,Jim

Yeh I did, I've tried with normal FSX learjet and it's ok so it must a PMDG 747 thing. It's hard to explain, the FMC shows correct altitude and I've set the altitude on the MCP but it just goes past assigned altitude, flight directer points the nose down but autopilot takes forever to react, I've tried V/S & FCH & ALT HOLD all with the same effect. I've disengaged autopilot and took over control and it goes extreme nose up, push right down on the stick and just about holds level. Yoke is calibrated and works fine with other planes.

This is probably better off in the PMDG forum, could this be moved please? I don't want to duplicate posts, thanks.