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Guest fmt008

b744 speed legs fmc problems

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Guest fmt008

hello,i have a problem with the fmc of 747.The fmc don't want to give speed to the PA when a speed is indicated in a leg .ex: lerga 1500/180in this case the speed of the 747 have to be 180 kts. In my case the fmc give the speed limit 250 kts under 10000 feets. It is impossible to have 180 kts when indicated in the speed legs.i don't understand the problem.for your information i have not the problem with the 737, fmc gives the right speeds legs to the PA as indicated.have you an information for me?in advance thank you for your answer.jp disperatifmt008

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I am not quite sure I understand your question but it is possible to put in a speed at a waypoint. It should be speed/alt and in your case in should be 180/1500.CheersSteve


Cheers

Steve Hall

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I'm not too clear either. From the example you gave, "1500/180" the plane reads this as 1500kt at FL180. Make sure you are inserting speed/altitude.

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Guest fmt008

thanks,ok i have writed an error, it is "180/1500" in my exemple.but i have the problem and yhe fmc don,t take the good speed of 180 kts but 250 kts (undr 10000 fts)jp disperatifmt008

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Guest fmt008

thnks,ok i have writed an error! in may exemple, it is "180/1500" in fact 180kts and 1500 fts. but the problem is always here, i have never 180kts in the PA but 250 kts as restricted speed under 10000 fts.jp disperatifmt008

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A very strange problem indeed. Please post a screenshot so we can have a better idea of what is going on.PaulPS. For restrictions to be met, VNAV must be ENGAGED, and the speed window closed. Make sure that these 2 conditions are met.

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>thnks,>>ok i have writed an error! in may exemple, it is "180/1500" in>fact 180kts and 1500 fts. >but the problem is always here, i have never 180kts in the PA>but 250 kts as restricted speed under 10000 fts.>>jp disperati>fmt008>For a AFDS commanded 180 knots you will be governed partially by FLAPS SPEED. VNAV cannot decel below min flap maneuver speed. First, set Flaps 1 at the UP bug, then flaps 5. The FMC restriction of 180 knots should now be commanded and displayed on the PFD since the maneuver speed for flaps 5 will be lower than the restriction of 180 knots.Best,Randy J. Smith


Randy J Smith

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Ahhh, it IS a clever wee airplane isn't it? :-)I love the way little things like this can go undiscovered by almost all users well into the life of the aircraft. Such is the complexity we've been provided with.


Mark Adeane - NZWN
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>Ahhh, it IS a clever wee airplane isn't it? :-)>>I love the way little things like this can go undiscovered by>almost all users well into the life of the aircraft. Such is>the complexity we've been provided with.>>Dontcha just love it!!!

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Guest fmt008

thanks,the vnav is engaged and the speed window is closed. concerning flaps, my take off configuration is flpas=10 . And i keep flap=10 because i want to fly at 180kts.really it is very stange and i have not explanation for that moment!thanks you very for all your ideas!!jp disperatifmt008

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