Why is my altitude constantly changing back and forth i...

[Guest Kiddpsychotic]

Hello everyoneI know that this problem has been posted and discussed here in other places, (of course, I did'nt see any solution); and I read all of those that appeared to pertain to this problem. but I don't understand why my 747-400 and 400F keep ascending and descending; it just keeps going up, then down, up, then down.The background: I am still using FS9, I recently installed it back on my computer after not flying for awhile. so I installed my 747-400 and 400F, as well as a few other add-on aircraft such as PSS concorde Pro, and a couple of Alphasim's aircraft. The 2 PMDG aircraft were installed with the sound update and a few liveries.I also downloaded and installed the latest version of FSUIPC 3.7.5.After doing my cockpit preparation and checks, I set up the FMC (I do have the latest Navagraph version 0713), Position Init; Route data, Perf Init; fuel reserves, cost index, Thrust limit; Takeoff Ref etc. click the FD switches, I set my speed selector to V2 speeds, arm LNAV and VNAV etc. WELL YOU GET THE PICTURE!After taking off and retracting gear with TOGA armed and activated, and retracting my flaps on schedule, I press one of the CMD buttons and everything about the takeoff goes really well.As the aircraft climbs, the annunciator has "THR REF" under autothrottle; "LNAV" under roll; and "VNAV SPD" under Pitch. Then at about 3-4 thousand feet the altitude indicator rises drastically and the speed begins to decrease because of the extreme pitch that the aircraft assumes, when the speed decreases to a very low point, then the altitude indicator begins to come down, and the speed rises. This activity continues all while the aircraft is climbing, even if I try to bring the pitch manually down by using my stick.Ocassionally the aircraft will do this even after achieving the criusing altitude; it will be flying straight and level for a good distance while enroute, then suddenly the aircraft will start losing altitude fast, then after descending rapidly, will just as suddenly start ascending rapidly, this is continued up and down, up and down.I have uninstalled the aircraft replaced the FSUIPC file with earlier versions, even uninstalled the entire FS9, reinstalled FS9 in a clean install with no other add on's and my PMDG Queens are still doing the same thing.I am at wits end, Please help. Thanks Harry

[downscc 1,327]

Try the same simulation without weather, clear skies, no winds, no AS6, ... you get the picture. It sure sounds like a wind shift problem.Good news is in FS9 the registered version of FSUIPC does a really fine job of taming the wicked MSFS WX engine. Too bad they can't work the same majic through simconnect in FSX.

[Guest Kiddpsychotic]

Thank You I'll try that Harry