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Guest KLM735

Changes in Speed and Altitude

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Guest KLM735

I have a question, in my flightplan for the 747-400 there is a change in speed and altitude that happens at a certain way point. I have both LNAV and VNAV set to on but the aircraft will not change its speed or increase its altitude to that stated in the FMC, but instead remains at its original alititude from the waypoint before. For example at waypoint 2321N the aircraft is supposed to be at .855/FL390, but instead it remains at .844/FL350. Does anyone know what I am doing wrong?

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Guest KLM735

So you have to set the altitude in the MCP Altitude Section becuase the FMC will not automatically tell the aircraft to change its altitude? How does the speed change to what is set in the FMC?

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Guest KLM735

No I have read this section in the manual but I dont understand. I understand everything but this, I would be very grateful if you assist me.Anton V. (thats my name)

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Hello Anton, The MCP works in conjunction with with FMC. If you have an altitude set lower on the MCP than your FMC crz alitutde the the aircraft will hold at the MCP altitude (Depending on the aircraft type it can go ALT HOLD/VNAV ALT). This does not work for speed since the speed window is blank (Which means you cannot adjust it). There is of course speed intervention which does allow one to manually adjust the speed and remain in the vertical mode (VNAV) by pushing the speed knob and setting the speed on the MCP (Handy feature I believe in RL). [h4]Randy J. Smith[/h4]AMD 64 4000+|ASUS K8V DELUXE|SAPPHIRE ATI X800XT PE|MUNCHKIN 3200|80 gig SATA|DELL 1905FP 19" LCD|TRACKir PRO|PFC JEPPESEN MOONEY YOKE|CH PRO PEDALS|


Randy J Smith

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Guest KLM735

So let me get this straight, so when the flightplan says that at a certain waypoint the aircraft should go to FL390, I have to enter 39000 in the MCP and set a VS, and press ALT and then once it has reached this altitude I should just hit VNAV again. I am still confused about the speed, so even if the FMC is programmed for the aircraft to speed up from .845 to .855, it will not do this on its own. I really appreciate all your help as I really want to learn how to operate this wonderful aircraft correctly.

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Guest brettdonahue

I too understand your frustration, these are very realistic sims and therefore can be quite complicated. What seems to work for me when you reach a step climb point is to as Randy said, change your MCP altitude, that is the altitude you see on your main panel, and then I will hit the FL CHG button to go up to the next level and or speed then hit VNAV. Usually you don't change your speed because it will usually be the same mach whether you are at FL300 or FL390. You also may have to change your cruise level listed under the VNAV. (Sorry I don't have FS and the FMC open to remember the exact button)Bretthttp://www.precisionmanuals.com/images/forum/800driver.jpg

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>So let me get this straight, so when the flightplan says that>at a certain waypoint the aircraft should go to FL390, I have>to enter 39000 in the MCP and set a VS, and press ALT and then>once it has reached this altitude I should just hit VNAV>again. I am still confused about the speed, so even if the FMC>is programmed for the aircraft to speed up from .845 to .855,>it will not do this on its own. I really appreciate all your>help as I really want to learn how to operate this wonderful>aircraft correctly. No. What I mean is this, if you have FL 390 set in the MCP window and you are in VNAV the aircraft will climb all the way to FL 390. If on the other hand you had FL 180 or any other altitude LOWER than the flight plan's "cruise altitude" then the aircraft will not climb higher than the MCP set altitude. To RESUME a climb one only needs to reset the MCP altitude on the MCP and push VNAV or the alt knob, depending on the aircraft we are talking about. I am not sure what is going on with the speed.[h4]Randy J. Smith[/h4]AMD 64 4000+|ASUS K8V DELUXE|SAPPHIRE ATI X800XT PE|MUNCHKIN 3200|80 gig SATA|DELL 1905FP 19" LCD|TRACKir PRO|PFC JEPPESEN MOONEY YOKE|CH PRO PEDALS|


Randy J Smith

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Guest D17S

Let's have a look at what you've got. First, let's start from cruise. You will have a cruise altitude set on the FMC

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