Can't Climb

[Guest navid]

Hello GuysI have been using PMDG 747 for about 4 years now, but never had a problem since 3 months ago, which my 747 can't simply climb,I'll give you the example, Right Now I'm Enroute OIII-KJFK, climbed to FL300 hardly, 300fpm, and after I reached Fl300 about 10 mins I started to loose speed, and nose go higher, FUEL: 261.9, ZFW: 516.7 CRZ CG: 23.4.So I descended to Fl200 gained speed and started the climb again but it simply couldn't and was getting the sort of BUZZ when you get close to MIN clean speedI thought it might be the activesky, closed it but still couldn't climb.registered FSUIPC VER 3.72Thanks

[Tabs 2,790]

Navid,The 747 can't climb immediately to high cruise altitudes at heavy gross weights. Check the FMC's CLB page and look at your OPT and MAX altitudes there. You want to fly at or just below the OPT one and then you need to step climb up to a higher altitude later in the flight as you burn off weight. I believe one of our Type Rating Course tutorials covers some step climb stuff.

[Guest navid]

Hi RyanThanks for you post, Im not a newbie, and I have atleast 3000+ hrs just with PMDG 744. OPT was FL324 and I was cruzing at FL300 and CON thrust LIM but it still couldn't cruize, I descended to FL280, still no luck, 260, 240, 220 and at FL220 I could maintain a Stable speed.P.S I have taken care of wind and presure smoothing is FSUIPC.Thanks again for your post.

[michal 44]

>I thought it might be the activesky, closed it but stillClosing activesky in the middle of the flight may not restore default weather conditions. Try to repeat the flight without using any outside weather program. Try to fly in standard weather and see what happens.Michael J.http://img142.imageshack.us/img142/9320/apollo17vf7.jpg

[Guest navid]

HiWhen I closed, the Activesky, I went to FSUIPC menu and clicked on "Clear All Weather".Anyways, I tested this in every condition, I have tried it, Online, Offline, with and without activesky, with completly no weather, and it just happens. I personally Can't thing of anything else, that why I have posted here,P.S I have formatted the HDD, New MB, New CPU, New GFX, totally new system, the only thing that is the same is my internet connection, that I don't really thing it could cause such strange behaviour in this bird.CheersThanks

[michal 44]

I would try to see if anything changes when you change your take off weight. Try to fly in a very light 747 - almost no cargo, no fuel. You should get phenomenal climb performance. Also I would creafully monitor outside temperature and see if it is near the expected values.Michael J.http://img142.imageshack.us/img142/9320/apollo17vf7.jpg

[Tabs 2,790]

I've really gotta think this is a temp/pressure related issue then. Does it only happen over specific areas/countries? I know Active Sky's coverage can be erroneous sometimes over parts of Africa, the Middle East, Siberia, the oceans etc where regular and accurate reporting is sparse...

[Auduns 0]

Hello NavidJust a quick question, what is your true/IAS speed setting in FS?I dont know if that has any impact on the PMDG 744, but i have seen it on other planes. I think it has to be set at IAS (indicated airspeed. If its set wrong, the AC will read the wrong airspeed, and will eventtually slow down and stall.This is just a thought from my side, and maybe worth checking. Maybe some of you other guys can confirm/disprove this.RegardsAudun

[Mats_J 2]

>Also I would creafully monitor outside temperature and see if>it is near the expected values.I'll go with Michael on this one. Check your outside temps when this happens. Climb performance (or any aircraft performance specs for that matter) is closely linked to the atmospheric conditions the aircraft flies through.Hope it helps,

[Jeff Nielsen 1,385]

You might also try deleting your FSUIPC.ini file just for good measure and let it rebuild a new one.

[Richard McDonald Woods 168]

Hi Navid!I am getting the same problem on my present flight GCTS-EGKK.FMC VNAV gives opt FL403, max FL440, and I have entered FL410 in ALT. Aircraft climbed fitfully until FL300, then the airspeed just drained away until stick shaker started. Commanded IAS is 307 but thrust is gradually draining away, and appears not to be trying at all to increase airspeed. I have then reduced the ALT to FL250, and the aircraft initially lazily increased airspeed up to the yellow warning band, but shortly afterwards started a precipitous climb (at times at 5000 fpm!) and thus draining even more airspeed. I have had to cease the flight now because I cannot figure out what is happening. Some other data - current gross weight is 230.3 tonnes, gear up, flaps up, F/D on, IAS/MACH blank, VERT SPD blank, A/P engaged, POS N33 46.3 W014 57.6, LNAV and VNAV engaged.I'm bailing out of this flight! Waaaaaaaaaaaaaaaaaaaaaaaaay! :-violin

[Chris from Angle of Attack 7]

This is an Active Sky issue. I have an experiment for you guys.Next time you're in a situation like this, look at your TAT above the EICAS N1 and then press pause. Watch the fluctuation in temperature. I've seen as much as a 40*C difference!ActiveSky will just tell you that 'it's warmer this time of year'. Is it honestly, on average, +3*C around the world at FL310?! I think not!You guys will find really no answer to this and no drive by ActiveSky to want to fix it.My first inclination was exactly like yours. 'Ah, it's gotta be weights!' Well, it's not! I've tried all different combinations. Even with the thrust set to CON in the THRUST LIMIT page, you won't be able to keep up with the draining speed.One thing that seemed to assist my situation was going into FSUIPC and changing the winds and temp changes to something like 1 degree per 5 seconds. It's ultra smooth, but it seems to have fixed the issue, for now.Let me know what you guys experience with these ideas, if you agree or disagree, etc. I'm interested to see what you come up with.

[Richard McDonald Woods 168]

Chris,Many thanks for your ideas. I shall try this out on my next flight.

[Richard McDonald Woods 168]

Chris,Forgot to say in post above that my THR mode was showing blank on my previous flight. This would presumably be a sim fault rather than a by-product of AS6?Today, with AS6 in operation (showing TAT at -18 at FL370), the climb was OK and everything went to plan.

[Chris from Angle of Attack 7]

That section should never be blank, and those are temps that finally sound normal.