I've spent a dozen hours already on this one.. can't play with the new toy unless FSX works. Here's what I've learned: Both FSX weather and ASX cause subtle variations in sea level pressure as you transition from one area to the next. Even if the wind shift isn't a problem, which it can be, these pressure shifts result in IAS jumping up or down 3-5 kts and the altimeter jumping up or down a couple of hundred feet. The absolute altitude or ground speed doesn't change, but the air model appears to create ambient conditions at flight levels based on sea level pressure (not realistic) as well as temperature and absolute altitude.The oscillations in IAS/Alt dampen, e.g. their amplitude decreases after the upset, unless the shifts occur more often than once per minute.I've noticed that if you have another non-FSX window open, such as ASX, then the oscillations increase rapidly in intensity.I've used ASX, ASX with FSUIPC4, and FSUIPC4 alone.. nothing smooths these pressure changes although FSUIPC4 seems to help with wind changes.HiFi simulation advertises that they are working with Dawson in trying to solve the problem, and will have another Service Pack soon.The only interim fix I have found is either set user defined weather or running ASX open the user defined weather screen to the advanced options where it contains the wx info feed by ASX and click OK. This freezes the wx to those conditions. In other words, only static weather works.

If this is really the case and so far the 744X can operate with STATIC weather only, I have to move back to FS9... Weather is an essential element of every flight; and with the long haul aircraft, crossing the atlantic/pacific without dynamic weather/winds aloft/turbulence takes most of the fun from flight planning, fuel planning and on-time-arrival (at least for me - being a virtual-airline pilot and enjoy on-line "as real as it gets" experience)Too bad... I'll wait for updates (and future SP maybe)Gil.

Gil,I agree with you about Wx being a major element in the long-haul business. I cannot fly with the oscillations, it just spoils the whole experience.Cheers, Richard

Another couple hours on this last night 400X KORD-PANC with a new download from ASX active (they didn't tell me they had a SP). I discovered that wx remains benign for about 20 min or more but then things start to happen. I played with all the settings in ASX and FSUIPC, which doesn't seem to help at all so I've taken FSUIPC4 out. Using ASX Build 1083 with Enhanced Route Coverage and Create Virtual Stations turned off, I could stop the stupid fluctuations by forcing a download. Most of the time, I couldn't force a download of new wx until I opened the settings page, made a minor tweak to allow me to force an update of settings, and then the download would happen (verified by looking at the activity on the indicators of my D-Link Switch) and all would be good in the world again until the next occurance.So, don't give up on FSX yet. The smart guys at PMDG, HiFiSim and others will once again find a way to turn a piece of Microsoft junk into a useable product. I don't want to throw my hands up and quit, when the smart guys need our feedback to get things working.

Dan,This morning I have reset all the FSX options to defaults, and then reduced all non-aircraft effects to zero. I then repeated my flight EGLL-KSFO without ASX. Took her from takeoff to FL100, then FL160, then FL200, FL250, and finally to FL290 as passed over Ireland and all was absolute smoothness!I can therefore only surmise, at present, that my surging was a result of the processor being swamped.Will keep trying variants as the opportunities arise,Cheers, Richard

So I set off yet again on EGLL-KSFO, this time with ASX running. Complex story follows:Levelled at FL100 after take-off. Surging by +/- 60ft returns (switched to std pressure at 7000ft). I feel that the differences could be caused by either ASX wx input, or because my processor is overloaded (most of the time core1 is 100%, core2 is 75-80%, processor 76%).Climbed FL100-FL140. ND wind dir/spd jumping all over. Climbed successfully to FL140 and settled.Climbed FL140-FL180. At FL180, speed exceeded command by ~70kts. All ASX winds showing ~335 deg at all levels, but ND showed 168/60.Climbed FL180-FL230. Climbed very quickly at expense of speed. Commanded 338, actual ~310. Aircraft settled at FL237 (commanded FL230!), then slowly continued to climb at commanded 338 kts over next ~45 mins (ECON CRZ showing OPT=FL313 MAX=FL355). At FL291, stick shaker. Commanded M.840, suddenly actual dropped to M.702. Aircraft still climbing and speed returning very slowly to M.840 (IAS 320). Sudden jump again to from indicated alt FL293-FL306 and in speed to IAS 370, then settled back into gentle climb (via temporary stick shaker). ASX still showing ~335 deg winds although ND showing jumping wind dir. At FL370 again jumping spd/alt and shaker.At FL343, still climbing at ~50 fpm, commanded speed M.839, actual M.810. CRZ alt still set at FL230. Wind indicated on ND at 331/52, TRK 280 deg, N1 103.1%. Speed now deteriorated to stick shaker at M.744 (commanded M.839) but still trying to climb (now at MAX ALT).Stopped flight as this is just incomprehensible.I hope this verbatim description can help someone determine the problems with this flight.Cheers, Richard

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Re-ran my EGLL-KSFO flight with ASX weather change speed turned down to 10%. Flight climb now MUCH smoother. So it would appear to be ASX upsetting my vertical profile. But I am not yet convinced that it is NOT the power of my PC being exhausted.Cheers, Richard