747-400X can't climb to FL340

[kozmicelly 0]

Hi, I flew my flight plan made by FSX planner, KSFO to KLAS led by FSX ATC, so I didn't use FMC control but autopilot (spd, hdg, alt). I'm surprised that 747 couldn't climb to FL340 (VS 100!) and almost stalled.Then somehow climbed to FL340 but could fly at best M0.7 or so (tail wind about 40).Fuel setting 2/3, Full pax.I figure for 747 FL340 and M0.8 is piece of cake. Can this be all right?? Anyone any ideas? Thanks in advance. RJTT

[NoahBryant 26]

What were you using for weather? When you see this again look at your outside air temp. Up that high it should pretty far below 0. I've found that some add on weather programs mess up the temperature some how and my plane wont climb because I will be at FL250 and the external temp will be +10 or something. Otherwise, I see no reason for you to have experienced that based on your flight details.

[scandinavian13 5,192]

First, you definitely don't need 2/3 fuel for that routing. Second, you were likely too heavy (see first, and full pax). Third, as mentioned, check the temperatures that were being provided by your weather application.

[kozmicelly 0]

Thank you two for your replies.As I'm new to this airplane I didn't know the best (at least better) airplane config.I use REX for weather. I didn't see the outside temp, but noticed the engine heating(?) warning.I noticed it but didn't know the meaning(s) of it, so I didn't know what I should do.Next flight I'll try to watch various parameters and try out some combinations.If REX did the low temp, what program should I use?Any recommendation? Thank you again. RJTT ( oh, it's 5:40 am)

[audiohavoc 24]

This is a common problem caused by abnormally high Outside Air Teperature (OAT). This commonly happens with FSInn weather. I avoid it by using Active Sky Evolution for the weather, and I disable all weather in FSINN. This gives me real world, dynamic weather with no strange temperatures and aircraft that perform as they should.

[NoahBryant 26]

I use ASE, and when I see the problem I just hit the refresh button and it re-downloads the weather and the problem is fixed. If that doesn't work, shut down your weather client, set FSX WX to "Clear Skies" and then restart your weather client.

[kozmicelly 0]

Thank you for your advices.I'll try each advice you two suggested. Thank you again. RJTT

[kozmicelly 0]

Hi, I could fly from KSFO to KLAS at FL340, M 0.85. 1/4 fuel, half pax, using REX.But I didn't know where I should look at to check OAT. I'll look it up in the manual and also the meaning of "FUEL TANK/ENG" and how to handle it.Anyway, it WAS a comfortable flight. Thank you all for the good advice. RJTT

[denthibbe 18]

Hi, I could fly from KSFO to KLAS at FL340, M 0.85. 1/4 fuel, half pax, using REX.But I didn't know where I should look at to check OAT. I'll look it up in the manual and also the meaning of "FUEL TANK/ENG" and how to handle it.Anyway, it WAS a comfortable flight. Thank you all for the good advice. RJTT

My guess would be that you were flying with both the "override pumps" and "fuel x feed" enabled. At 1/4 fuel loaded (actually anything below 120k lbs of fuel), both should be disabled.Have a look at page 50 of the Aircraft Systems documentation. Hope this helps.

[kozmicelly 0]

Hi denthibbe, Thank you for your advice.Yes, I looked it up in the manual and found the meaning of it and how to handle it.Anyway I thank you so much.I'm encouraged to fly by many kind people here. RJTT