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Guest matey

PMDG 744 - FMC speed problem during APP

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Guest matey

Hi,When I approaching the same airport I had two different experiences with the FMC.First time I enter all speeds for the descent (bellow 10000 feet nominal speed 240kts): 220kts at 5000, 200 at 3500 170 at 1500, and finally I select in the APP page flaps 25

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How are you entering the speeds?For 220 at 5000 you should have typed 220/5000. You need to enter this against a specific waypoint on the legs page. On the VNAV descent page there is a standard speed transition of 240/10000 which you can delete if you want to. There is also the option of putting in a non waypoint specific speed below the speed transition entry. Here you could put your 200/3500 for example.CheersSteve


Cheers

Steve Hall

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Guest matey

Yes thats correct Steve, I typed 220/5000 on the legs page, and sometimes all subsequent waypoints till the rwy change their speeds to 220, and sometimes not, there must be a logic that I am not able to find. Last time all subsequent waypoints changed I noted they all have an altitude in big fonts, maybe that is the reason.By the way 240/10000 is for the descent, the same is true for the climb (250/10000). I can delete this standard restriction. Once I did this in order to comply with ATC instructions but than I couldn

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>How can I change the standard speed transition of 250/10000 to>for example 300/10000? Do I need to delete that field first>and use the field below for the new speed entry?Is this for the desent? If so you delete the standard 240/10000 entry and put 300/10000 in the speed restriction area below it. You must make sure that the descent speed in the FMC is higher than 300 otherwise it will use the standard econ speed or whatever speed you entered if less than 300. In otherword the aircraft has to be programmed to be descending faster than 300 knots at 10,000ft so that it has something to decelerate to. It will not accelerate to it.CheersSteve


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Steve Hall

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Guest matey

Yes that part is clear, in fact the case that I had was during the climb.ThanksMatey

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>Yes that part is clear, in fact the case that I had was>during the climb.Why would you want to change it to 300/10000? The only reason it is there is that this is the required speed for flight below 10,000ft in most countries unless cleared otherwise. If you want to climb at 300 kts then you can delete the 250/10000 restriction. If you have 300 knots set in the VNAV climb page then this is the speed that the aircraft will climb at in VNAV mode.CheersSteve


Cheers

Steve Hall

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Guest matey

>Why would you want to change it to 300/10000? Because the ATC instruct me to climb without speed restriction above 5000ft.>The only reason>it is there is that this is the required speed for flight>below 10,000ft in most countries unless cleared otherwise. If>you want to climb at 300 kts then you can delete the 250/10000>restriction. I have three fields in the VNAV CLB page: Econ Spd (for example 306/0.821), Spd Trans (250/10000) and Spd Rest (blank).If with this configuration suppose that at 5000ft ATC instruct me to continue the climbt without speed restrictions, that means I am allowed to achieve the Econ Climb Speed 5000ft before reaching 10000ft. What I did was delete the Spd Trans field so I had Econ Spd 306/0.821, Spd Trans (blank), Econ Spd (blank) and supposed that the plane would continue climbing on 306kts because the speed restriction bellow 10000ft was no more there, but in fact it continued on 250kts so I was forced to use the MCP speed knob again :-( with 306kts set. What am I supposed to do in that case?>If you have 300 knots set in the VNAV climb page>then this is the speed that the aircraft will climb at in VNAV>mode.Where did you mean exactly in the VNAV CLB page?ThanksMatey

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Guest matey

Please disregard last message, I have tried it again and after deleting the Spd Trans field before 10000ft and Exec the action, FMC automatically selects Econ Spd for the rest of the climb.Thanks and sorry for the botherMatey

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