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hariseldon

unable to reach programmed altitude - cannot mantain speed

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Hi,although I suppose to have done all procedures correctly, with my first flight (KIAH to EDDF) I cannot reach FMC programmed altitude (FL330).the engines stay above 100% (although everything is "green"), I'm stuck at FL320, and from time to time a sudden medium pitch crackling sound bursts, coupled with loss of speed, and lasts for a few minutes, then againanti-ice systems are onam I too heavy?is it a weather engine fault? (I'm using REX's, I'm aware that at high altitude FSX weather system is terrible)thanksMarco Gabbrielli

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Are you using Fsinn by any chance? If so then you need to disable Fsinn weather.Tim

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Just out of interst. You might want to check how much fuel you have on board at the time. I remember as a new PMDG 747 driver having this issue and had a chat with a RealWorld 747 Co-Pilot over in a local forum and he pointed me in the direction of fuel loads and after altering my fuel or programming step climes i was right as rain! :-)Regards

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I am having the same problem at the moment and I am stuck at FL320 as well and I think it is because the aircraft is too heavy. For some reason I have been given far too much fuel for my trip.Maybe it would best if you adjusted the fuel load editor before taking off

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First, anti-ice should only be on in icing conditions (-8 to +8 C with visible moisture), cruise is far too cold to bother with it, and anti-ice saps engine power because it uses more bleed air (which is pulled from your available thrust).Second, make sure you're properly loaded for the flight. This is a simulation of a 747, not a gamey toy that you can load to the brim and go firing off into the distance. Take a look at the Type Courses that properly describe how to set everything up. There's also an entire section of the manual devoted to planning a flight. I suggest that, if you read nothing else, you read that part.Third, if you're using any third-party weather programs, check to make sure that it is not giving you false temperatures. A general rule of thumb is that the temp should decrease 2 degrees for each 1000' of altitude. (REX should be fine here, along with ASE).

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First, anti-ice should only be on in icing conditions (-8 to +8 C with visible moisture), cruise is far too cold to bother with it, and anti-ice saps engine power because it uses more bleed air (which is pulled from your available thrust).Second, make sure you're properly loaded for the flight.  This is a simulation of a 747, not a gamey toy that you can load to the brim and go firing off into the distance.  Take a look at the Type Courses that properly describe how to set everything up.  There's also an entire section of the manual devoted to planning a flight.  I suggest that, if you read nothing else, you read that part.Third, if you're using any third-party weather programs, check to make sure that it is not giving you false temperatures.  A general rule of thumb is that the temp should decrease 2 degrees for each 1000' of altitude. (REX should be fine here, along with ASE).
1 in this case I made a mistake: I turned anticing on as soon as I passed 10000 (did I find it somewhere in the fifteen manuals or among the procedures?)2 I followed the load manager numbers3 about the weather engine: I turned off REX weather engine (which had reached OAT until -27, on august 22...) and Idea.gifloaded Active Sky Evolution (which I had almost forgotten to have, as REX gives better visuals, in my opinion): in a few minutes everything went fine: OAT dropped to -14, and the 747 made effortlessly its climb to cruise level

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What do you mean "you followed the numbers"? The load manager is not a dictator. It is a reporter. It only tells you what weights you are sending to the aircraft, not that the weights are acceptable for flight (other than exceeding MZFW and MGW). If I set a very heavy weight in the load manager, load a high amount of fuel, and try to climb to an altitude above the high 20s, it's not going to work. In order to see weight versus altitude, read the section of the manuals dealing with cruise planning.From what you wrote it seems like it was a weather issue. Glad that's sorted.

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or, maybe, at the same time I had consumed all the excess fuel I loaded (I confess I had a 747 near to the max weight limits ... 849000lbs) happy.png , as you pointed outjokes apart, the sudden drop of temperature has been more than a clue

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