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MrSpeaker

Help with FMC

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I need some advice. I try to build a flight plan with FsCommander then put it in the coroute. The plan shows up but after I set up the altitude.It says Cruze unable. also on the first page of the fmc the sat-m sat-s acms cmc and memory lsk are unselectable. I new to the PMDG and a little lost on everything any help would be great.

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Hi,Welcome to the forum.. you should sign your name when you write post (it's the rules and you'll get told off if you don't).. I am sure they'll probably let it go as it's your first post..ANYWAYUNABLE CRZ ALT probably means that you've selected a cruise altitude that the aircraft won't be able to get to.. There are a number of reasons and common reasons (usually procedure and lack of understanding are the root causes.. BUT.. that's not a criticism.. we all start somewhere!)..OK.. You've selected at target cruise altitude that the aircraft is too heavy to attain. The reason probably is you've thought that when an airliner flies it does so at one level throughout the trip.. That is not true.. An example I can give you..London Heathrow (LHR) to Los Angeles (LAX).. The initial altitude (that which you will enter as CRZ in the CRZ page) is FL330.. it's not higher than this.. because the weight doesn't allow it.. (the aircraft can go higher but not much and it's uneconomical).. BUT.. as we cruise along and burn fuel and our weight changes.. the optimum cruise altitude also changes.. it gets higher.. SO.. on the trip we make some climbs.. these are called STEP CLIMBS.. and are usually 2000 feet each.. and you can enter your step climb interval into the FMC.. to allow it to calculate when.. you'll make your step climb..Take a look at the data in the PMDG manual regarding cruise weights and heights and you'll see what I mean..SO.. takeoff at LHR.. then climb to our first optimal target cruise (in the crz page) of FL330.. then fly along.. one optimal is roughly or just under FL350.. set new cruise altitude and then initiate the climb.. (first step climb).. the second to FL370.. etc.. I usually finish my LHR to LAX flights at FL380.. IF you set FL380 initially.. the aircraft is too heavy.. but once over the Atlantic a lot of fuel is burned and FL380 becomes a viable altitude.. I imagine this is what's happened to you..Hope that helps..CheersCraig

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Thanks Craig for taking the time to explain this to me. Do you know of any websites that can make the fmc manual a little easier to understand. I having some serious problems with all aspects of the fmc. Its a very humbling aircraft to fly. Thanks again for your help little by little I will start to understand. Ian Beggs

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Hi Ian,There is only one way to understand the FMC througly, and that is ... yes ... read the manual.Read that manual (he is enormous h

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OK thanks for the advice William. I just bought it and I guess I'm a little to anxious to get it going. I realize that there is a learning curve, so I will read the manual again and again.Thanks: Ian

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