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JSACKS

PMDG 747-400 question about flap markers on PFD

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I know, I know, this is not the PMDG forum; however, I've posted there and no replies and I don't think I'm going to get any, so here goes on the FS2004 forum:On approach in the 747-400, after filling out the APPROACH REF page, I observe the small green flap markers on the left side of the PFD, by the speed tape. When dropping the flaps and slowing down during approach, I have the following setttings: UP, 1, 5, 10, 20, and REF. There is no marker for 25 or 30. When I drop to flaps 20, the green "20" disappears immediately and all that remains for the balance of the approach is REF. Is it supposed to be this way? Why do I think I am missing at least the flap 25 marker? Or has is never been there?Appreciate any posts, thanks, and again apologies for posting here about this matter.JS

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I'm at work for the next 8 hours so I can't check... But from memory I'm sure flap 25 and flap 30 would not have a marker since they are vref speeds (depending on what you selected on the app page)If your flying the fs9 version it's 100% correct, havn't flown the fsx version yet. Rob

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Hi JS,When dropping the flaps for approach, there are critical speed limits for the settings for 1, 5, 10, and 20... but 25 & 30 are based on VREF settings and the speed difference between the two settings is so minute that there's no need for reference marks on the PFD. Generally speaking, at higher speeds, there's more chance of damage to the flaps if they are deployed above their limits (and, of course, more chance of a stall if they are NOT deployed within the referenced speeds on the tape).. thus the specific reference to those settings on the speed tape... but the difference between speeds for flap settings of 20, 25, and 30 is very little and the aircraft should be slow enough, so really there's no danger of flap damage at those speeds.. thus there's really no need for a tick mark on the speed tape to reference those settings... they all fall within your VREF speed limit, so that's why after 20, the next reference on the PFD speed tape is VREF.Hope that helps!- Alex

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Rob and Alex:Thanks for your posts. You are right. Now I see it better. I had wondered about the REF situation and figured it might make sense for no more flap markings to appear but it's funny, despite using the 744 500 times in the past 18 months or so, I could not remember if something had gone wrong with her on approach!Alex, your explanation was very clear and welcome. Thanks!Now I could feel relieved and go back to simming in the Queen as normal, hooray!JS

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