Hi folks,

 

the tutorials teach us to use after 40% N1 in T/O the TO/GA mode by pushing the hidden click spot aside the left course knob (or a self defined button on our side/joysticks) or the actual button on the thrust levers.

 

Why don't we push simply the N1 button below the A/T ARM switch?

What is the difference? (I think in MD11 I can use it. )

 

I know also that in 737NGX pushing it is to no avail...

 

Thanx in advance,

19AB67

 

 

You use the TO/GA switch because it puts the computers in the appropiate mode.

 

BTW, unterschreib doch bitte mit deinem realen Namen, so wie es in den Forumregeln verlangt wird. Ansonten wird dein Post gelöscht!

You use the TO/GA switch because it puts the computers in the appropiate mode.

 

This does not answer the question.

Why does pushing N1 not put the computer into TO/GA mode?

I think TO/GA sets the takeoff thrust while N1 sets the climb thrust. Maybe someone else will confirm.

Hi folks,

 

the tutorials teach us to use after 40% N1 in T/O the TO/GA mode by pushing the hidden click spot aside the left course knob (or a self defined button on our side/joysticks) or the actual button on the thrust levers.

 

Why don't we push simply the N1 button below the A/T ARM switch?

What is the difference? (I think in MD11 I can use it. )

 

I know also that in 737NGX pushing it is to no avail...

 

Thanx in advance,

19AB67

 

I don't think the N1 button will work to set takeoff thrust. It will set climb thrust. N1 mode will activate if LVL CHG is activated during climb or if VNAV is activated during climb.

 

The MD-11 doesn't have a N1 button. You press the AUTOFLIGHT button (arms autothrottle) and the thrust levers will automatically advance to T/O when the thrust levers are at 65% N1 or higher.

BTW, unterschreib doch bitte mit deinem realen Namen, so wie es in den Forumregeln verlangt wird. Ansonten wird dein Post gelöscht!

Ich denke daß er nicht verstanden hatte...

Hopefully that's remotely right. I haven't spoken/written German in maybe 5 years?

 

This does not answer the question.

Why does pushing N1 not put the computer into TO/GA mode?

It does actually answer the question, albeit indirectly. Your first question about why one doesn't use N1 instead of A/T was answered: it doesn't place the system in the right mode (or the one you'd want it in).

 

Hopefully, I'll explain this correctly:

N1 is simply a thrust mode. It has no associated pitch command, and as such, there is no speed protection. This mode essentially places the engines on whatever rated thrust is possible (as mentioned, in CLB mode), and how you manage that thrust to stay in limits is on you. TO/GA on the other hand, provides speed protection to a certain degree, as it commands the F/D to indicate a pitch up attitude.

 

As far as human factors issues go (not considering the actual uses of the modes), it's better to have the button for whatever mode you'll be using at your fingertips. As you take off, you're going to have your hand on the throttle, and you're going to want to leave it there, so it's best to hit the TO/GA button because it's right on the throttle itself.

Either button will tell the engines to follow the current N1 limit. If you hit TO/GA, the FMA shows N1. However, the TO/GA mode can only be entered by hitting the TO/GA buttons, and you need that mode for the vertical guidance.

 

N1 button = N1 Guidance.

TO/GA = Vertical + N1 Guidance.

Thanx Matt and Kyle.