To be honest, I don't know if this is a problem caused by AS... but it seems like the most logical place to search for help. If I don't find any hear, I'll try elsewhere.The problem is that my aircraft gains/loses 30, 40, 50, or more knots seemingly at random! Today during climbout through FL290, I got a huge boost and went from a 1500'/min climb to a 10,000'/min climb [using the Level Change autopilot function]. Then in cruise an hour later, I went from 280KIAS to 195KIAS in about 5 seconds. During this time the winds aloft as indicated by the PMDG panel were constant. During descent then I went from 315KIAS to 360KIAS instantly.. then overspeed, overstress, crash. Variations of this have occured on many of my previous flights in all of my PMDG aircraft [b1900D, B737-6/7/8/9, B747] [haven't flown anything else for as long as i can remember... maybe I should be asking PMDG?]. This occured with AS5 as well.AS6's latest build was in use [downloaded 28Dec] and I had turned off vertical air simulation. Aircraft was a PMDG B737-800. No special scenery. No other wx programs running, I was running SB3 but with it's weather turned off. There were no storms anywhere in the vicinity of my flight. I'm utterly complexed... this has to be a "sim-ism" as the folks at NASA say!Steve Perry

Hi Steve,Try to reset FSUIPC back to Default settings and Weather Settings Off.Hope this helps,Jimhttp://www.hifisim.comhttp://sales.hifisim.com/pub-download/asv6...development.jpg http://sales.hifisim.com/pub-download/asv6-banner-proud.jpg http://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

Hi,Also make sure you're on the latest FSUIPC 3.52.. 3.51 had wind problems.VAS can also effect your cruise airspeed, you may want to turn this down..Best,