Hi .

I have a question about the N1  button  on the MCP.

I tried to do a take off with LNAV en VNAV not armed, after liftoff and above 400 feet engaged LNAV, LNAV comes online, then, when the PFD mode enunciator changed from TO to ARM and before thrust  reduction height pushed the N1 button and it was my believe that the climb mode would then be engaged, climb would be on the upper EICAS and N1 on the PFD mode enunciator. But nothing happened..I can not  manually select N1 with the N1 MCP switch, only at thrust reduction height entered in the CDU N1 engages.

Am I wrong to believe that in the real plane this can be done?

Thanks

ivo

Hi, since there is no answer I will refrase the question.

Could anyone with the PMDG 737 700/800/900 NGX  set the Thrust reduction height to for instance at 1500 feet in the CDU and  after ARM is anunciated on the PFD push the N1 button and see if it comes on?

I want to make sure that my installation isn't corrupt.

 

 

 

 

the PMDG FCOM vol II on chapter 4.20.13 clearly states that  N1 can be engaged by pushing the N1 knob!!

ivo

I tried it and am seeing the same thing as you: N1 can't be enabled manually between the moment the A/T mode changes to ARM, and point where the thrust mode switches to N1 automatically (when crossing the thrust reduction altitude). I'm not sure if this is a bug or a feature...

The a/t only changes to N1 when transition hight is reached and the alt is changed by the pilot to the next highest alt given by atc..and yes you can manually engage it...

 

Edited April 2, 201313 yr by BRIAN1158

I'd suggest that's a bug. The A/T remains in THR HLD until 800ft RA then changes to ARM. At this point you are supposed to be able to select N1 manually.

 

This is similar to another question I saw a while ago where a second press of the TO/GA switch below 800ft was not selecting full GA thrust. I'll have to run some tests to see if they are related.

On the 737 Flight crew training manual  page 3.32 is written

"On airplanes with FMC U10.8 and later , VNav armed  on the ground  with the appropiate acceleration altitude entered is the recommended technique for acceleration"

"At thrust reduction altitude ,verify that  climb thrust is set at the point selected on the takeoff reference page.If thrust reference does not change automatically, select climb thrust."

So, when N1 does not arm after the thrust reduction altitude, I think it will arm  when pushed, 

Also interesting is on page 3.1 "Although some 737/300/400/500 airplanes may be equipped with FMC U10.8, the FCC will not permit LNAV or VNAV to be armed for takeoff."

ivo

On 737 N1 can be selected after ARM mode is engaged. On NG's this occurs after 800' RA.

 

 

"Although some 737/300/400/500 airplanes may be equipped with FMC U10.8, the FCC will not permit LNAV or VNAV to be armed for takeoff."

 

Classics have other logic. For another example, N1 can be selected after 400' and 18 sec after liftoff are passed.

On the 737 Flight crew training manual  page 3.32 is written

"On airplanes with FMC U10.8 and later , VNav armed  on the ground  with the appropiate acceleration altitude entered is the recommended technique for acceleration"

"At thrust reduction altitude ,verify that  climb thrust is set at the point selected on the takeoff reference page.If thrust reference does not change automatically, select climb thrust."

So, when N1 does not arm after the thrust reduction altitude, I think it will arm  when pushed, 

Also interesting is on page 3.1 "Although some 737/300/400/500 airplanes may be equipped with FMC U10.8, the FCC will not permit LNAV or VNAV to be armed for takeoff."

ivo

I don't think this has anything to do with VNAV, it's about the A/T in takeoff mode.

Hi .

I have a question about the N1  button  on the MCP.

I tried to do a take off with LNAV en VNAV not armed, after liftoff and above 400 feet engaged LNAV, LNAV comes online, then, when the PFD mode enunciator changed from TO to ARM and before thrust  reduction height pushed the N1 button and it was my believe that the climb mode would then be engaged, climb would be on the upper EICAS and N1 on the PFD mode enunciator. But nothing happened..I can not  manually select N1 with the N1 MCP switch, only at thrust reduction height entered in the CDU N1 engages.

Am I wrong to believe that in the real plane this can be done?

Thanks

ivo

You're right ! In the PMDG 737 NGX.....unlike real ones, N1  button doesn't work when pressed at MCP. It's a feature in PMDG 737 NGX add-on. The only way to engage N1 after ARM appear at FMA is through CDU ATHR Reduction at N1 page programming...That it's !

 

Regards,

 

Marco Aurelio