During a recent flight, my autopilot went haywire. I followed the PMDG directions to the letter for programming the FMC and the MCP. When the plane was close to reaching cruising altitude, it missed the level off point programmed in the FMC and MCP and started undulating up and down accompanied by a strange drop in the altitude tape. According to MSFS 2004 (shift Z) I was as hight as 41,000 feet but the altitude tape dropped to 15,000. The airspeed tape also did strange things like fluctuating up and down with no throttle input and in level flight. Any thoughts?C.D.

Hello C.D or whatever your name is......You didn't by ant chance use online weather,or any weather program?Johnny"I'LL BE BACK"[div align=center]http://www.avsim.com/hangar/fly/josve/pmdg.jpg ][/div

As a matter of fact, I was using the MSFS 2004 on line weather. I was testing some recent tweaks to my system, FS9.cfg, BIOS, etc trying to get more mileage out of my decent machine. I'm using the "frame rate friendly" clouds talked about so much in MSFS forum to no avail. Strange thing is I've used MSFS 2004 on line weather lots of times with the PMDG plane without any problems. Do you think that was the cause of the anomolies?

That is my real name. Or at least what people call me.

Sounds like you flew into a bit of cloud icing. Try to fly with the anti-ice switches engaged, should work then :)