I have been unable to sucessfully step climb to FL400 using the 8i. I use the 747-400 Load Manager and Vroute (PMDG 747-400 Fuel Profile) to plan the flight. My FMC says FL355 is optimal but I can't physically get the plane to that altitude or above FL310. If I use the 747-400 I have no problems at all. Has anyone else had this issue or does this amount to operator error? Can the 400 and 8i use the same load manager? PMDG you have done a great job with the 747 family and I can't wait to fly the triple 7 and the 737....:(

Its because you are too heavy, hence the existence of step climbs.If you load a tiny bit of fuel, say 50x1000 LBS, you will be able to rocket up at VS's of 4500 FPM.

My FMC says FL355 is optimal but I can't physically get the plane to that altitude or above FL310. If I use the 747-400 I have no problems at all.

Its because you are too heavy, hence the existence of step climbs.

He said optimum was FL355. And no problems in the -400.

Load manager and V-route have nothing to do with it, if you have correctly configured the FMC and it says Optimal is FL355. Of course, if you have given the FMC the wrong figures and are in fact overweight, all bets are off. Otherwise, I would guess that you are using external weather of one form or another and your TAT is too high.

I Figured it out I had to disable FSINN weather.... as soon as I turned it off the TAT dropped 40C and the plane started climbing.