Old good FSX

[V12]

Of course it was AP problem. Triggered by baro altitude change 1200 feet in half of second at FL500.

[Richard]

I'm also seeing this problem; I've posted onto the main forums and I'll investigate further.

There are two parts to the issue;

1) it appears that the outside pressure is changing almost instantly for an as yet unknown reason.
2) The autopilot in your aircraft can't handle the sudden pressure change.

The F-15 holds altitude fine; possibly because to maintain M2.5 it requires the engines to run at 100% with a degree of thrust augmentation.

I'm not an expert on the upper atmosphere - however lower down you certainly can get rapid pressure changes as the aircraft flys through different airmasses; so the autopilot should be able to handle this.

I'll investigate(1) to see if I can figure out what is happening - but also the autopilot should be fixed on your model.

[V12]

Next step to the reality - Android app PMDG CDU device. With this little application You will transfer CDU to the tablet.