NG Level Off (FMA FMC SPD/ALT HLD) Question
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NG Level Off (FMA FMC SPD/ALT HLD) Question
Hello sirs,
I have a question that I hope someone can confirm for me. Here is the situation. (Non- SPD/ALT INT MCP)
I am climbing in VNAV towards my CRZ ALT (FL310) but have leveled off with the MCP (15000) at a altitude lower than my CRZ ALT. FMA shows A/T=FMC SPD/ALT HLD and my IAS/MACH window is *Blank* when it would normally allow me to access in *ALT HLD*. Now, ATC tells me to change speed. How does one change speed here seeing that I would have to change pitch modes to unblank (access) the IAS/MACH window? I cannot use V/S seeing that I would have to change the ALT window. Is it possible to change my Target CLB spd? (EDIT: It's really not in VNAV so I guess no) Thanks for any answers.
Crvm
I have a question that I hope someone can confirm for me. Here is the situation. (Non- SPD/ALT INT MCP)
I am climbing in VNAV towards my CRZ ALT (FL310) but have leveled off with the MCP (15000) at a altitude lower than my CRZ ALT. FMA shows A/T=FMC SPD/ALT HLD and my IAS/MACH window is *Blank* when it would normally allow me to access in *ALT HLD*. Now, ATC tells me to change speed. How does one change speed here seeing that I would have to change pitch modes to unblank (access) the IAS/MACH window? I cannot use V/S seeing that I would have to change the ALT window. Is it possible to change my Target CLB spd? (EDIT: It's really not in VNAV so I guess no) Thanks for any answers.
Crvm
Last edited by crvm; 26th Sep 2003 at 11:23.
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No, that will not work since I am really not in * VNAV* any longer although FMC SPD is annunciated, I call it limbo Vanv. Of course this is not a problem on the SPD and ALT intervention MCPS... I guess I will have to engage MCP SPD then resume after clearance but seems to defeat the purpose...
Well a pilot buddy told me that one can sekect LVL CH seeing that you won't change altitude because the alt is not changed and this too will allow access to speed selection, I think that going MCP SPD is the best way so far
Thanks for chiming in
Crvm
Well a pilot buddy told me that one can sekect LVL CH seeing that you won't change altitude because the alt is not changed and this too will allow access to speed selection, I think that going MCP SPD is the best way so far
Thanks for chiming in
Crvm
Last edited by crvm; 27th Sep 2003 at 03:54.
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Hey Lem,
Well because I am already in "ALT HLD". Any time you level off with the MCP with a set altitude lower than you set cruise alt the aircraft goes FMC SPD/ALT HLD. In this particular case the window will stay blank, why it does not go MCP SPD insted of FMC SPD is beyond me, I guess it has really not left VNAV, that's why I call it limbo VNAV, regardless I will have to dial in a higher alt and engage VNAV to get climbing again. Just had me wondering the procedure for changing speed here ...
Well because I am already in "ALT HLD". Any time you level off with the MCP with a set altitude lower than you set cruise alt the aircraft goes FMC SPD/ALT HLD. In this particular case the window will stay blank, why it does not go MCP SPD insted of FMC SPD is beyond me, I guess it has really not left VNAV, that's why I call it limbo VNAV
, regardless I will have to dial in a higher alt and engage VNAV to get climbing again. Just had me wondering the procedure for changing speed here ...
Last edited by crvm; 27th Sep 2003 at 20:01.
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crvm,
when FMA says FMC SPD, it really means that i.e. speed control from FMC. therefore, to alter the speed, just enter a new speed in your FMC CLB page.
although, FMA says ALT HOLD, it is still considered as in VNAV as your VNAV on MCP is still engaged, right? therefore, an alternate method is to exit VNAV by hitting ALT or FLCH thereby opening the MCP speed window giving you manaul speed control.
hope this helps...
SR
ps. i dont fly the NG but the 777, but i reckon the AFDS is pretty much the same. it's a boeing, ain't it?
when FMA says FMC SPD, it really means that i.e. speed control from FMC. therefore, to alter the speed, just enter a new speed in your FMC CLB page.
although, FMA says ALT HOLD, it is still considered as in VNAV as your VNAV on MCP is still engaged, right? therefore, an alternate method is to exit VNAV by hitting ALT or FLCH thereby opening the MCP speed window giving you manaul speed control.
hope this helps...
SR
ps. i dont fly the NG but the 777, but i reckon the AFDS is pretty much the same. it's a boeing, ain't it?
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" it is still considered as in VNAV as your VNAV on MCP is still engaged, right?"
Hello sir,
Well I am not sure what you mean by *engaged*? If you mean if the MCP VNAV button is illuminated then no because VNAV disengages ALTHOUGH the FMA shows MCP SPD. I was under the impression that one pays closer attention to the FMA than to the MCP indications.
This *might* be a NG thing. Trust me you would think Boeing would keep things pretty common but it's just not the case. For example, In TOGA one can move the IAS *one click* and the speed on the* MCP* window and the SPD Bug (magenta) will jump to the F/D command = V2 * 20.
I'm sure a Southwest pilot would know having the same type of MCP...
Crvm
Hello sir,
Well I am not sure what you mean by *engaged*? If you mean if the MCP VNAV button is illuminated then no because VNAV disengages ALTHOUGH the FMA shows MCP SPD. I was under the impression that one pays closer attention to the FMA than to the MCP indications.
This *might* be a NG thing. Trust me you would think Boeing would keep things pretty common but it's just not the case. For example, In TOGA one can move the IAS *one click* and the speed on the* MCP* window and the SPD Bug (magenta) will jump to the F/D command = V2 * 20.
I'm sure a Southwest pilot would know having the same type of MCP...
Crvm
As has been said before, the easiest way of opening the speed window is to press alt hold, thus releasing speed control from the FMC. I am pretty sure it is the same for -3/4/500s and NGs.
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chuck said it right.
Also you can press alt hold. It is wise not to push buttons for diferent modes that the one you're in.You are level in alt hold,better push 'alt hold'. Generally,it won't do any harm to push also 'lvl chg' ,but there can be some blips in the computer,which,for ex,will start retarding,or advancing thrust,then realising it's actual mode will return to normal.Nothing dangerous but somewhat anoying.Been there,done that.)
I usually enter the speed on the climb page
hy Alex
Also you can press alt hold. It is wise not to push buttons for diferent modes that the one you're in.You are level in alt hold,better push 'alt hold'. Generally,it won't do any harm to push also 'lvl chg' ,but there can be some blips in the computer,which,for ex,will start retarding,or advancing thrust,then realising it's actual mode will return to normal.Nothing dangerous but somewhat anoying.Been there,done that.
)I usually enter the speed on the climb page
hy Alex
Only half a speed-brake
It is also perfectly possible to press ALT HOLD for IAS/Mach window to open. Tried it on purpose yesterday, albeit on a -500.
Punch the (unlit) ALT HOLD button, IAS/Mach window opens, FMA annouces framed MCP speed, ALT HLD remains.
I've also been taught to check modes on FMA (!), but also to understand MCP green lights - green light indicates a mode that can be disengaged, e.g. APP it is not. Under your scenario of intermediate level off, the FMA displays ALT HLD, but VNAV button light remains on. Thus if VNAV may be disnegaged, it must presumably be some sort of activated.
.
Cheers,
FD.
Punch the (unlit) ALT HOLD button, IAS/Mach window opens, FMA annouces framed MCP speed, ALT HLD remains.
I've also been taught to check modes on FMA (!), but also to understand MCP green lights - green light indicates a mode that can be disengaged, e.g. APP it is not. Under your scenario of intermediate level off, the FMA displays ALT HLD, but VNAV button light remains on. Thus if VNAV may be disnegaged, it must presumably be some sort of activated.
.Cheers,
FD.
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Crvm,
Flight detent just gave the right answer to your question.
Although all other answers and suggestions would solve the problem, I reckon your main conflict is the FMC annunciation of an ALT HOLD (What you rightly describe as 'limbo VNAV)
Yes, don't be afraid, press the ALT HOLD button again, even though it is already annunciated,and all will be revealed.
Safe flying,
uneasy
Flight detent just gave the right answer to your question.
Although all other answers and suggestions would solve the problem, I reckon your main conflict is the FMC annunciation of an ALT HOLD (What you rightly describe as 'limbo VNAV)
Yes, don't be afraid, press the ALT HOLD button again, even though it is already annunciated,and all will be revealed.
Safe flying,
uneasy
