I've noticed that since I have done a reinstall, there are some major issues with the aircraft. The flight is all planned as normal. Get the weights and all that, load the fuel correctly for the flight. I run through the flight and everything acts and runs normal. However, I'll get in flight at around 1.5 to 2 hours in. I'll start to hit bumps and whatever else. The funny stuff starts happening. The speed starts to die off, and no matter how hard the engines try, they cannot keep up. I've even tried setting it to CON thrust, to no avail. Right now it is BARELY holding speed, and that's after it took 20 minutes to increase the speed 20 knots. The aircraft just doesn't have the strength to stay up.Other notes here-Flight Level is modified for the weight. To start, anywhere from 300 to 330, depending on the flight. -FMAs all check out normal. SPD/LNAV/VNAV PTH -FMC set up correctly. No derates to speak of.-Payload and fuel weights all check out. Payload is around 127,000 pounds.-Winds are normal. Currently nothing more than 30 knots in either direction.-One time I came back to the sim in stick shaker, and it wouldn't climb up for the life of me. Current altitude was 14,000 feet, with less than a quarter the amount of fuel the bird can take.As you can see, it makes no sense to me at all. Please bring up thoughts and ideas. I believe this is some sort of technical issue, and not a lack of procedure on my part. However, I'm also open to being wrong.Thanks in advance

Actually, I've experienced exactly what you are describing. Have a look outside, you may be in the middle of a thunder storm. The bumps is turbulence. I can't figure out why the engines can't produce enough power afterwards to keep the aircraft up high. The only sound theory that I have is that the temperature is so high that the engine can't warm and expand the condensed air enough at higher altitudes. Roughly where are you when this happens? It only happens with me in thunder storms in area's near the equator. If you see the Inter-Tropical Convergence Zone (ITCZ) on your TEMSI with thunder storms in the area, STAY AWAY! Overall, It's only started to happen this summer so I would say stay away until the upper atmosphere starts to cool down. Ryan GamurotLucky to live Hawai'ihttp://www.virtualpilots.org/signatures/vpa296.png

What weather are you using, and from what source? Please post your real name. Thanks-John

Using Active Sky of course.Guy Palmer

Please see the dozens of messages related to Active Sky on the forum (throwing up unrealistically high TAT (temperatures) ;) Airplanes don't like high temps at high altitudes ;)Cheers.Q>