B747-400X FMC Messages

[zachlog 18]

Where are the FMC messages documented for meaning and action ? Got message "CHECK ALT TGT".

[downscc 1,327]

I don't remember where or if the messages are in the documentation; however, this message occurs when the FMC is telling you it expects you to change the MCP ALT to a different value... almost always when a top of descent is arriving and it is programed to start a VNAV descent but you still have the cruise altitude set in the MCP. The proper action is to reduce the MCP ALT to the next constraint if you're going to fly VNAV, or if you are flying ATC instructions either ignore the message or change from VNAV to something else like MCP SPD and ALT HOLD until the ATC clearance to descend.I don't use VNAV for descent but many do.

[zachlog 18]

Thanks for the information.>>I don't use VNAV for descent but many do.Out of curiosity, why do you not use VNAV ?I am asking because I am new to PMDG and tried to do everything by the book the first time around until I get a better feel for the product. When using a fully automated SID/cruise (have not done descents or landings yet with this one), the aircraft's behavior seems a bit "unusual" though I am not yet sure what to expect. For example, I get climb rates of 3,000 - 4,000 ft/min when going from 10,000 ft to FL180 and this seems excessive....at least to me at this point. Smooth as silk when I fly it manually (through the MCP). However, I would like to do it right so trying to understand and use the FMC as much as possible.Thanks

[tfm 169]

Your climb rates do not surprise me, assuming your load is not very high (and possibly even if it is). The 747 does not lack power. Apparently it can take off pretty much like a rocket on a light enough load. In practice, most people will takeoff and climb at a de-rated thrust to spare the engines (and the passengers). I read somewhere that de-rating the takeoff thrust by just 5% on a 737 can save 50% on maintenance/wear & tear costs. Try using CLB-2 (available on "Thrust Limit" screen in the FMC).Tim

[zachlog 18]

>>Your climb rates do not surprise meWow !!!!! I did not realize this and could not fathom how an aircraft of this size could climb at this rate thus my suspicion I was missing something in the FMC.Thanks againZach

[FLEX1978 373]

Zach, Do s search on the forums for a program called TOPCAT. It will help you enter Derates and assumed tempretures in the FMC before departure. unless your at max T.O.W or departing in heavy rain it's best to derate the engines.Robhttp://forums.avsim.net/user_files/183112.jpg