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Ty53650

NADP 2 FMC settings

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when doing a NADP2 departure, would I input 800 agl as reduction altitude and 3000 for acceleration alt? Trying to wrap my head around this, seems easy enough but would like some clarification. Thanks!


Ty J. Peres - KBZN

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I always confuse NADP1 and 2. Basically for any departure procedure, you need an altitude where you reduce from takeoff to climb power and an altitude where you start accelerating to 250 kts. NADP 1 and 2 are simply standard procedures that specify these altitudes. Some airports have specific altitudes that differ from NADP1/2. If I am recalling correctly which is which: NADP1: Hold V2 + 10-20 kts until 3,000' AGL with thrust reduction to climb power at 1,500' AGL. For this, you would put 1500 as your thrust reduction altitude and 3,000 for your acceleration height. NADP2: Hold V2 + 10-20 kts until 1,500' AGL at which point you both reduce power to climb thrust and begin accelerating to 250 kts at the same time. For this, both your thrust reduction altitude and acceleration height should be entered as 1500. Hopefully I didn't confuse these two, I've been known to switch which is which (probably should look it up again to clarify for myself). Eric Szczesniak


Eric Szczesniak

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Looking at the info I have (www.b737mrg.net), it looks like for a standard NADP2 you'd reduce to climb thrust and accelerate to flaps up speed at 800 ft AGL, then upon reaching 3000 ft AGL, you'd accelerate to normal climb speed, so I'm a bit confused why you'd leave thrust reduction/acceleration altitude at 1500ft? This is the issue I'm having, which altitudes to input on the takeoff ref. page 2 in the CDU?


Ty J. Peres - KBZN

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This is the moment where you bio-chem professor told you that his class would save your life... NADP:1:a coenzyme similar to NAD and present in most living cells but serves as a reductant in different metabolic processes.


Dave-Aerosoft-2021-Small.png

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Ok, I've found an old post stating the original release was wrong in the fact that the magenta speed bug would jump to V2+20, where as the latest hot fix (4) has fixed this. The FD commands a pitch to maintain V2+20, but the actually magenta speed bug stays at MCP set speed, or V2 in this case. Problem solved as far as that's concerned. So I guess my final question is, when doing a NADP2 departure, how would this procedure be flown while having VNAV armed before take off? How would the procedure be flown if VNAV was NOT armed or used for take off? Finally, what would you set as thrust reduction/Accel. ht on Takeoff Ref. Page 2? Would thrust reduction ht be 800ft AGL or 3000ft AGL? Or perhaps the other way around? Bare with me here guys, I'll get this if it kills me! Thanks!


Ty J. Peres - KBZN

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There's a few ways of doing this. At my last airline, we would take off in VNAV and use speed intervention at the acceleration altitude and cancel that at 3,000' At my current airline, takeoffs are not in VNAV. At 1,000', Bug UP, N1, Flaps 1.


Matt Cee

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Alright, starting to get this. So do you always use quiet climb for the NADP 1 and 2 procedures? If not, I'm still unsure of what to put for thrust reduction ht/acceleration ht on takeoff ref 2 page. If CUTBACK is always used for NADP procedures, then disregard. Thanks Spin737, speed intervention makes sense, I will try both methods you've described.


Ty J. Peres - KBZN

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apparently reduction and accel alt do not currently function correctly. The reduction from take off to climb thrust setting on Takeoff pg 2 was being ignored. I submitted a ticket and was told that it would be fixed in SP1. Thinking that the fix might be in HF4, I tried different altitudes for reduction and accel alt and it seems that it is still is not fixed. Since this is a complex sim, it is possible that I am not doing something exactly correct so if others can alter the transition from takeoff to climb thrust using the reduction alt on pg2 of the Takeoff page then please report back. No matter what I set reduction alt to, the NGX switches to climb thrust around 800'.


Cheers, Scott Ball

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Simply put: if you want to fly NADP 2 with Vnav armed and cutback option off, set you thrust reduction to 800 and accel height to 800 as well. After rotation, follow the bars which will get you going on v2+20 (roughly). At 800' AGL confirm that you are no longer at takeoff thrust (you should now be on climb thrust) and witness the bug being cued to 230kt. Use speed intervention to command the bars to get you to flaps up speed, just like Matt said. Once you get to 3000', cancel the speed intervention and the AFDS will command pitch to accelerate and maintain 250kt until 10000'. Which is exacly what Matt said in an earlier post, excepet his airline finds it better to perform these changes at 1000' instead of 800' AGL.


Cheers,
Victor M. Lima
 

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People, don't forget the 800' are a MINIMUM. You don't HAVE to be that early although many do it. It could very well be 1000' or also 1500' AFE. This graphic might be helpful. If you really want 800' as thrust reduction, then NADP 1 could be 800 red/3000 acc, and NADP 2 could be 800 red/800 acc. If you fly those with VNAV armed on ground you don't have anything to worry about. Interesting hint with speed intervention, although I wonder if it's necessary. VNAV would command 230 initially upon acceleration, and if you keep retracting flaps you should not have any problems with speed limits. At least I never had. Once flaps are up you'll see climb speed, usually 250 below 10K, or your final climb speed should you have removed that restriction. sig.gif

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People, don't forget the 800' are a MINIMUM. You don't HAVE to be that early although many do it. It could very well be 1000' or also 1500' AFE. This graphic might be helpful. If you really want 800' as thrust reduction, then NADP 1 could be 800 red/3000 acc, and NADP 2 could be 800 red/800 acc. If you fly those with VNAV armed on ground you don't have anything to worry about. Interesting hint with speed intervention, although I wonder if it's necessary. VNAV would command 230 initially upon acceleration, and if you keep retracting flaps you should not have any problems with speed limits. At least I never had. Once flaps are up you'll see climb speed, usually 250 below 10K, or your final climb speed should you have removed that restriction. sig.gif
I don't have the docs in front of me, but we weren't supposed to accelerate until 3,000'. If you start your clean up at 1,000', you could be at 250 too low. That's why Bug Up until 3,000.

Matt Cee

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I don't have the docs in front of me, but we weren't supposed to accelerate until 3,000'. If you start your clean up at 1,000', you could be at 250 too low. That's why Bug Up until 3,000.
Ah alright. I always thought once you acceleration height you were free to go. Learn something new every day. Will reconsider if my usual practise of arming VNAV on ground whenever possible makes a lot of sense then. sig.gif

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You usually are, accel height in all cases means lowering acft body angle and accelerating to 250 or first speed restriction of the sid and cleaning up as you go. NADP2 however, is a little different since you basically have two accel heights, so to speak. One happens concurrently with thrust reduction and it should be at least 800 AFE. however you do not acceleate fully. You accelerate to you flaps up maneuvering speed and you climb with reduced thrust at that speed until 3000' at which point you resume acceleration. Thus in your fmc you should program thrust reduction and accel height to the same height, and use speed intervention (if using vnav) between that height and 3000.


Cheers,
Victor M. Lima
 

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Perfect, I appreciate all the help guys, I usually make things much more complicated than they have to be...A lot of great info here! I'll also double check to see if the NGX ignores the altitudes set on takeoff page 2. Once again, thanks to all of you, now off to practice!


Ty J. Peres - KBZN

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