Sign in to follow this  
ideoplastic

Weather changes and loss of speed

Recommended Posts

Very happy with the 747 overall, however have been encounteringtwo minor problems.First is I'll be flying at cruising level at the relevant speedwith autopilot on LNAV/VNAV. Suddenly Active Sky 6 will do a weatherupdate and the aircraft speed drops considerably (say from 290 to240 KIAS) triggering the stick shaker warning sound. At this pointI have to engage the Thrust or Level Change buttons to try and regainthe original spped.Second on quite a few instances after take off and engaging LNAV/VNAV and on thrust reference, the aircraft after reaching FL290 or so will again begin to loose speed and the stick shaker warning sounds. In such instances it appears that the aircraft nose is far too high and that the aircraft would require trimming, however I've not been able to achieve this without disengaging the autopilot.Upon re-engaging AP the trim goes back to its original position(nose up 5degress plus). By switching to thrust/level change eventually and very slowlt the aircraft will regain enough speedto keep on climbing.Could be I'm doing something wrong but unsure what. I've been usingFMC for various aircrafts over the years, so fairly conversantwith their programming.Thanks in advance.

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

Joaquin,If you have a registered version of FSUIPC, you can easily resolve this annoying behaviour by setting up wind transitions.These transitions will allow you to smooth out any wind speed or direction changes that occur when your weather is updated.Hope this helps.Regards,Lee.

Share this post


Link to post
Share on other sites

Ive got a registered copy of FSUIPC and it makes very little differenceI have also been experiencing the same issues with you apart from when i have them its hitting thunderstorms. It can't maintain any altitude or speed. I have to clear all the weather, shut down AS6 and then found that my plane was left at a 10 degree nose pitch up which kept it at level flight. Then i found that it couldn't maintain speed. Im not sure what it is, but its very annoying.It happens on both my pc's, both have had fs2004 reinstalled, formatted you name it its had it.I suppose this must be another thing to add to the bugs listCheersBen -RSR 23JAN06

Share this post


Link to post
Share on other sites

Which version of FSUIPC do you have? There was a problem with version 3.51, which has now been solved (causing me to have problems which sounds to be very similar to yours)./ Jesper

Share this post


Link to post
Share on other sites

Ben-This particular phenomenon has little to do with the -400. It is the result of a very poor weather implementation within MSFS.If you use the search function in this forum, you'll find that it has been discussed in great detail previously.It is not "something to add to the bugs list." Search/Read/Learn!

Share this post


Link to post
Share on other sites

Its only started happening since ive patched the 744, thats why i wouldn't think it was FS2004Cheers Ben

Share this post


Link to post
Share on other sites

>Second on quite a few instances after take off and engaging >LNAV/VNAV and on thrust reference, the aircraft after reaching>FL290 >or so will again begin to loose speed and the stick shaker>warning sounds. In such instances it appears that the aircraft>nose is far too high and that the aircraft would require>trimming, however I've not been able to achieve this without>disengaging the autopilot.>Upon re-engaging AP the trim goes back to its original>position>(nose up 5degress plus). By switching to thrust/level change>eventually and very slowlt the aircraft will regain enough>speed>to keep on climbing.Check your fuel/payload weight and check the MAX and OPT altitudes on the FMC VNAV CRZ page - you're probably trying to climb too high for your weight...

Share this post


Link to post
Share on other sites

Hello Joaquin,*** For the autopilot disengaging issue: As mentioned already, this happens due to poor wind modeling in FS2004 and it happens with me on not JUST the 744 but the PSS 772LR also. I use accelerated simulation up to 8x and even 16x (with the PSS) and this can momentarily disengage the autopilot in both these but as long as it resumes on its own (engine autostart button ON should help I think), then you should be OK. The problem seems to occur ONLY when switching views, for example, from map view back to the accelerated simulation or after saving while still in accelerated simulation mode. However, I do realise that it DOES occur even in normal 1x simulation but the effect is too minor for me to be of any consequence - I only have problems in accelerated mode.Do you use accelerated simulation rates by any chance?*** As for the speed dropping and nose going up: The other thing I noticed is that when working the the FMC (OR CDU in the PSS 772), ONE CAN ACCIDENTALLY TOUCH THE FORWARD SLASH "/" KEY and ENGAGE the SPOILERS with full deflection! I have been having your problem with the PMDG 744 and with the PSS where the speed drops drastically almost to stall point. In today's flight (with the PSS 772LR) and in last week's flight with the PMDG 744, I discovered that my spoilers were deployed while in mid-air (cruising)!Go to your FS2004 ASSIGNMENTS section in the SETUP and DELETE KEY ASSIGNMENT for the forward slash "/" key for activating spoilers as we use the "/" for entering SPEED / ALTITUDE restriction in the LEGS page of the FMC so it is very possible to activate the spoilers in this way. I had just finished entering the STAR waypoints and speed restrictions in my CDU today and noticed a sudden drop in speed - since I was prepared - I switched to SPOT view and confirmed that the spoilers were activated "inadvertently".Hope this helps.Can (John) Agbaba

Share this post


Link to post
Share on other sites

Well thanks to everyone for all the replies.Some comments.I enabled the relevant section of FSUIPC (v3.53) anddid not notice much improvement on the problem with thesudden changes in weather. If this is due to FS9 limitationsthen the next obvious question to ask is why isn't this problemoccuring with other aircraft I have (payware & freeware).I don't normally accelerate simulation and when the problemsoccured it was under x1 simulation.As regards weight vs altitude, I would like to comment asfollows:I always use the PMDG pull down menu to load fuel.At various times with a full fuel load and ZFW within permitted weight after programming the FMC for FL320 it will give me a message like max alt FL130 or something equally low. Not being an expert:Isn't a fully loaded 747 able to climb to a modest FL320, even if slowly?Deployed spoilers by mistake were never an issue.I don't own a PSS777 so unable to comment in that respect.Once again thanks

Share this post


Link to post
Share on other sites

Hi, Jaquin, I ave the same problem as you. When I use 8x acceleartion then I first have to stop ASV 6 and all weather. Then it work, but it isn

Share this post


Link to post
Share on other sites

it was recommended on the ActiveSky support forum to download the latest FSUIPC and also the latest updates to ActiveSky 6. This should stop the dramatic shifts in wind

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this