Crazy plane behaviour

[El padrino 2]

I tried a flight from Athens (LGAV) to Bangkok (VTBD) in order to check the UT2 interaction and several other aspects of the plane as I'm still in the process of learning.I used FSCommander for the flight plan, the PMDG load managerand a fuel planner in order to get weights, travel time, step climbs etc correctly.So more than 30mis into the flight and well into the CRZ phase of the flight I decided to take a few nice screenshots as LNAV & VNAV were flying her...... while suddenly a steep left turn and "bank angle" shouting!!!The turn looks bad from the inside too......and an immediate right turn as the plane was strugling to find the correct path (it was still on LNAV & VNAV).The plane continued rolling left and right without reason as I was checking the FMC and the EICAS for abnormalities (which I found none). I have several screenshots which I can upload if you want.From the contrails you can get an idea of what the plane was doing!!! Not the smoothest flight ever :( I managed to calm her only through setting the HDG after which she flew straight and steady. My only question in this situation is the green arrow on the Fuel EICAS after I shut down the Center fuel pump as the tank was almost empty. What's this arrow?Then for no apparent reason shestarted overspeeding...After she calmed down again it looked OK again, but... once we got close to the next waypoint... the beast was unleashed!To the right......or to the left......here is the path she followed!!!However after we passed the last w/p she decided to follow the plan, as planned. At this point I must note that I had already turned NAI and WAI (nachelle and wings anti-ice) on, as I thought this behaviour might have been an icing issue (although no warning ever came out).But that wasn't the end! I thought it was now over until I noticed the speed

[Guest CBRDoc]

I tried a flight from Athens (LGAV) to Bangkok (VTBD) in order to check the UT2 interaction and several other aspects of the plane as I'm still in the process of learning.I used FSCommander for the flight plan, the PMDG load managerand a fuel planner in order to get weights, travel time, step climbs etc correctly.So more than 30mis into the flight and well into the CRZ phase of the flight I decided to take a few nice screenshots as LNAV & VNAV were flying her...... while suddenly a steep left turn and "bank angle" shouting!!!The turn looks bad from the inside too......and an immediate right turn as the plane was strugling to find the correct path (it was still on LNAV & VNAV).The plane continued rolling left and right without reason as I was checking the FMC and the EICAS for abnormalities (which I found none). I have several screenshots which I can upload if you want.From the contrails you can get an idea of what the plane was doing!!! Not the smoothest flight ever :( I managed to calm her only through setting the HDG after which she flew straight and steady. My only question in this situation is the green arrow on the Fuel EICAS after I shut down the Center fuel pump as the tank was almost empty. What's this arrow?Then for no apparent reason shestarted overspeeding...After she calmed down again it looked OK again, but... once we got close to the next waypoint... the beast was unleashed!To the right......or to the left......here is the path she followed!!!However after we passed the last w/p she decided to follow the plan, as planned. At this point I must note that I had already turned NAI and WAI (nachelle and wings anti-ice) on, as I thought this behaviour might have been an icing issue (although no warning ever came out).But that wasn't the end! I thought it was now over until I noticed the speed

[downscc 1,327]

My goodness that was a lot of pictures, and Troy did a quote reply so now there's twice as many.Problem is probably MSFS wx engine, solution is probably a registered copy of FSUIPC and use it for wind/temp/pressure smoothing. Not much you can do about the unrealistic temps, were you using default weather or default real world weather? I think either ASX or REX does a lot better than the default stuff.

[El padrino 2]

My goodness that was a lot of pictures, and Troy did a quote reply so now there's twice as many.Problem is probably MSFS wx engine, solution is probably a registered copy of FSUIPC and use it for wind/temp/pressure smoothing. Not much you can do about the unrealistic temps, were you using default weather or default real world weather? I think either ASX or REX does a lot better than the default stuff.

Thanks for the replies guys.Troy you're absolutely correct. Haven't noticed that the centre tank had 0 fuel after a while. Good info!@ downscc: I only use ASA that's why I found particularly weird this kind of temps. I also have a registered FSUIPC, which -now that you mentioned it- have not checked for a long time. Will probably have to make sure everything's going ok in it.By the way I use REX only for the textures as I find ASA easier to understand (and according to what people say on various forums it has a better wx engine).

[El padrino 2]

It was there all the time!!!According to ASA manual, Page 9:"When using PMDG 747, MD-11 or other high-sensitivity aircraft, turbulence effects can result in stability problems and potential s-turn autopilot hunting. Both FSUIPC turbulence effects (enabled when FSUIPC wind smoothing is enabled) and FSX internal turbulence effects (used by ASA and FSX itself) can cause these problems. In order to eliminate these harmful effects, it is recommended to minimize/disable turbulence effects in both FSUIPC (if in use) and FSX.FSUIPC (if installed and FSUIPC wind smoothing/turbulence effects are enabled) - Edit These FSUIPC.ini settings:TurbulenceRate=0.5,2.5TurbulenceDivisor=40,40,80,80FSX - Edit the following FSX.cfg setting (under [Weather]):TurbulenceScale=0.500000FSX

[Turbine777 13]

It was there all the time!!!

Hi George, Another culprit that stains any weather engine is "Saved Default Flights". If your loading up to a saved default, you might notice much better results if you delete them, they get corrupt all the time and can reak havoc on all parts of the sim (not just weather). I think FS somehow re-accesses these weather fields that are saved and tries to add to weather, rather than replace (just a theory).Another good practice to get into is to use FSUIPC's "Clear all weather" after loading the flight, then loading your weather scheme or refreshing your other wx. This is recommended by REX also, and I have yet to see the high TAT issue that's being debated as a High-Fi issue ever since I got into this practice. I have also noticed a much better flight experience all around with the PMDG's doing this as well.

[dazz 69]

When you had those speed problems you had no speed mode enabled. I can see LNAV & VNAV PATH, but no speed mode... and that's not strange since your autothrottle switch is off. :D

[El padrino 2]

When you had those speed problems you had no speed mode enabled. I can see LNAV & VNAV PATH, but no speed mode... and that's not strange since your autothrottle switch is off. :D

You're absolutely correct, however even with thrust manually adjusted at max the speed was still just above stall while I lost a few thousand feet. It seems to be an ASA or FSX related problem -according to the relevant forum- and the speed problem is the plane's reaction to abnormal temperatures. So it's 100% not a PMDG problem (which makes me very happy :( )As regards lateral navigation the answer is quite obvious that it's ASA...

[Turbine777 13]

You're absolutely correct, however even with thrust manually adjusted at max the speed was still just above stall while I lost a few thousand feet. It seems to be an ASA or FSX related problem -according to the relevant forum- and the speed problem is the plane's reaction to abnormal temperatures. So it's 100% not a PMDG problem (which makes me very happy :( )As regards lateral navigation the answer is quite obvious that it's ASA...

George, Did you read my post above? I've read the relevant forum discussions for months, but as I said in my previous post, have yet to see this problem again since doing as I described.

[El padrino 2]

Hi George,Another culprit that stains any weather engine is "Saved Default Flights". If your loading up to a saved default, you might notice much better results if you delete them, they get corrupt all the time and can reak havoc on all parts of the sim (not just weather). I think FS somehow re-accesses these weather fields that are saved and tries to add to weather, rather than replace (just a theory).Another good practice to get into is to use FSUIPC's "Clear all weather" after loading the flight, then loading your weather scheme or refreshing your other wx. This is recommended by REX also, and I have yet to see the high TAT issue that's being debated as a High-Fi issue ever since I got into this practice. I have also noticed a much better flight experience all around with the PMDG's doing this as well.

I usually start my flights from scratch and end them in one session. In addition I have fsx.cfg configured not to preload the default flight exactly to avoid corrupted wx files.Today I tried a flight, without loading a flight plan on ASA, in which I observed weird behaviour again (albeit of much less degree) but once I climbed on high FLs I turned to FSX update-every-15-mins weather and then back to ASA and everything went smooth for the next 2 hours (both lateral navigation and air temperatures). I have also adjusted FSUIPC ini file and fsx.cfg according to the ASA manual suggestions which might also contribute to the improvement.As regards the FSUIPC "clear all weather" seems to be a good practice, just one question though. Don't you use wind smoothing and the various random turbulence and icing options? You just keep everything off? And how do you setup your flights? eg should I load a flight plan on ASA which I start after I initialise my flight?Would it be possible for you to write the steps you follow in order to setup your flights?Really appreciate your help, thanks!

[Guest markhall]

can someone help please??!!... i have the SAME problem!!... right after takeoff, while making a runway heading climbout.. if i take a look at the NAV display(map view), the aircraft obviously has to be over the white dotted line indicating the runway heading (as seen on the nav display)... but the plane drifts(to the right) like being caught on a heavy cross wind or something.... and when i turn the plane using heading select to intercept the magenta route before arming LNAV, the plane turns but when i arm LNAV the plane goes beyond the magenta line (again, to the right) and when i bring the nav displays map view down to 10nm range, i see that the plane is facing the magenta line about 4 to 5 nautical miles away from the line, constantly making minor abrupt turns(which is never realistic obviously)... please help!!!!.... by the way, all this after setting up the FMC PERFECTLY!!!.. i also have the overspeeding problem if i arm LNAV.. so im forced to stay on SPD select, manually entering the speeds....

[Paul_Smith 92]

can someone help please??!!... i have the SAME problem!!... right after takeoff, while making a runway heading climbout.. if i take a look at the NAV display(map view), the aircraft obviously has to be over the white dotted line indicating the runway heading (as seen on the nav display)... but the plane drifts(to the right) like being caught on a heavy cross wind or something.... and when i turn the plane using heading select to intercept the magenta route before arming LNAV, the plane turns but when i arm LNAV the plane goes beyond the magenta line (again, to the right) and when i bring the nav displays map view down to 10nm range, i see that the plane is facing the magenta line about 4 to 5 nautical miles away from the line, constantly making minor abrupt turns(which is never realistic obviously)... please help!!!!.... by the way, all this after setting up the FMC PERFECTLY!!!.. i also have the overspeeding problem if i arm LNAV.. so im forced to stay on SPD select, manually entering the speeds....

The problem is still the FS weather engine which is a POS because in all the dynamic modes, it switchs from one weather state to another abruptly. (Think 20 knot head wind becoming 30 knot tail wind in an instant - no plane can handle sudden 50 knot changes!) REX, ASA etc. all have the same issues. The only known solutions (and it is only a partial solution) is to use a feature of the registered version of FSUIPC to smooth wind changes or do not use dynamic weather.

[Guest markhall]

oh thanks.. but, there is just one more thing thats VERY odd, and i have to share it!... EVERY TIME i fly the IFR flight starting from the runway, everything works fine, as in, the plane encounters absolutely no problem... but when i create the same flight with the same weather situation and aircraft setup from the GATE!!, thats when the problem occurs!!... right after i align the IRS and the nav map is alive, i clearly know that the aircraft will not fly well, because the aircraft in my case was placed exactly 90 degree away from the runway at the gate, but the nav display always shows the aircraft pointing 5 to 6 degree to the right of the perpendicular to the runway(90 degree)... so when i encounter this problem i hit "alt" and open the map view and drag the aircraft to the active runway, and after doing that, i went through the IRS procedure again and set the right position in the FMC, and then the nav display clearly shows the aircraft well placed at the runway and a flight after that is problem free... but whats strange though in all of this is that, if i get the pushback from gate and do the taxi and align the plane to the runway and then try to do the IRS procedure again, it never works.. i HAVE to hit "alt" go to the map and drag the plane to the runway, go back to the aircraft and do the IRS procedure to make a good flight... so - a flight directly from the runway shows no problem AT ALL!!...a flight from the gate always goes bad!...do you still think its the weather engine??.. by the way, i have FS9 not FSX.. so REX or ASA have nothing to do with my FS..

[Paul_Smith 92]

oh thanks.. but, there is just one more thing thats VERY odd, and i have to share it!... EVERY TIME i fly the IFR flight starting from the runway, everything works fine, as in, the plane encounters absolutely no problem... but when i create the same flight with the same weather situation and aircraft setup from the GATE!!, thats when the problem occurs!!... right after i align the IRS and the nav map is alive, i clearly know that the aircraft will not fly well, because the aircraft in my case was placed exactly 90 degree away from the runway at the gate, but the nav display always shows the aircraft pointing 5 to 6 degree to the right of the perpendicular to the runway(90 degree)... so when i encounter this problem i hit "alt" and open the map view and drag the aircraft to the active runway, and after doing that, i went through the IRS procedure again and set the right position in the FMC, and then the nav display clearly shows the aircraft well placed at the runway and a flight after that is problem free... but whats strange though in all of this is that, if i get the pushback from gate and do the taxi and align the plane to the runway and then try to do the IRS procedure again, it never works.. i HAVE to hit "alt" go to the map and drag the plane to the runway, go back to the aircraft and do the IRS procedure to make a good flight... so - a flight directly from the runway shows no problem AT ALL!!...a flight from the gate always goes bad!...do you still think its the weather engine??.. by the way, i have FS9 not FSX.. so REX or ASA have nothing to do with my FS..

I have never heard of that one before. What heading shows on the nav display, and what heading do you think it should show? Perhaps you could post a screen shot of this.

[downscc 1,327]

Hard to tell, maybe the registry repair tool should be given a try.