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Guest matey

PMDG 747-400 CDU speed input problem

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Matey in the RW 747 you cannot enter a speed at a waypoint unless that altitude is either in large font or you enter both the speed and alt which will cause it to be entered in large font. There are other options for speed control as well and they can be found on the VNAV descent page. Not really much point in putting speeds on the final approach (if an ILS) as these are not flown in VNAV so are pointless. If you want to protect yourself from arriving hot and high then put something like 210/4000 or the like. When you are manouvering for the GS the speed window should be open and as flap is put out you bug back to the next flap extention speed.CheersSteve


Cheers

Steve Hall

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Did it again. That post is mine.


Mike Roth

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Guest D17S

So, during a VNAV PATH descent, if you want to enter a speed target at a specific waypoint, you have to enter a fixed altitude target too. More or less? I

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Very well put Sam. I've done enough typing over the last few days.....my finger hurts.CheersSteve


Cheers

Steve Hall

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Guest matey

Thanks Sam, I understand what you try to explane, also thanks to Steve for his patience with all my questions, and knowledge of the real 747! Finally I also find a explanation in the PMDG 747 Manual, on chapter 12 FMC User's Manual page 26 under the title Speed Constraints:"...Speed constraints must be always entered in association with an altitude constraint..."Thats the way it is implemented in the 747 and in the PMDG 747, I don

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Pretty much the case Matey except the last paragraph should be the other way around. If you program in a high speed descent then the TOD will be closer to destination and the descent angle will be steeper. If you then try to fly down that generated path at a slower speed then you will need speed brake to stay on it. Better LD ratio back at the lower speed. The reverse is true if you try to fly fast down a low speed programmed descent. You will need to apply thrust to reduce the rate of descent to stay on the path. Try it and see.CheersSteve


Cheers

Steve Hall

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