I'm not sure what I'm doing wrong, but after my plane reaches T/C isn't the CDU suppose to automatically switch to CRZ mode? Instead it keeps saying CLB. I don't ever recalling it acting this way.

I think this is an airline option - you will find it somewhere in the options.  Check the manual.

 

Cheers,

Hi,

 

First thing before asking on the forum, check the manuals:

Introduction manual p83

Thanks guys, will do.

If you are talking about the thrust limits on the EICAS display, that's an option. However with the CDU, I don't know if that's because the vnav isn't set up correctly or what.

 

Also, if you have any questions, feel free to come here. Whether you read the manuals or not. The manuals for this type of airplane are huge and it's something that could take quite some time. Not everyone has time to learn an airplane like this. Let's be real, people go through training programs for this airplane that are full time hrs for a month at the least.

 

That being said, come on by, ask questions and let us help you understand this airplane.

Hi,

 

Reading again the whole thread, a doubt crossed my mind and I may have answered too quickly.

Are you talking about the CLB/CRZ thrust limit in cruise or the cruise VNAV ACT ECON CRZ page of the CDU?

Thanks a lot Matthew, I really appreciate that. I'm not really doing anything different when programming the CDU before flight. When I use X-Plane 10's FlightFactor 777, it doesn't give me problems. the CDU will automatically switch from CLB to CRZ after it reacher T/C. But I'm not sure why it's not doing this in PMDG's 777.

 

I've looked at page 83 of the introduction manual and couldn't find anything related to this.

Hi,

 

Reading again the whole thread, a doubt crossed my mind and I may have answered too quickly.

Are you talking about the CLB/CRZ thrust limit in cruise or the cruise VNAV ACT ECON CRZ page of the CDU?

 

I'm referring to the status display in the EICAS... where it says CLB on the top... that should switch to CRZ after your plane hit's T/C but mine remains in CLB forever.

Aaron,

 

My apologies, I think I misread your issue. The FMC should change from ACT ECON CLB to ACT ECON CRZ when it reaches the altitude set in the CRZ ALT box of the PERF INIT page.
Are you sure that the altitude you set on the MCP and the one you set in the PERF INIT page of the CDU are the same?

 

 

I'm referring to the status display in the EICAS... where it says CLB on the top... that should switch to CRZ after your plane hit's T/C but mine remains in CLB forever.

 

Aaron,

 

I hope my first post was not rude, it is not intended.
But the solution is indeed in page 83 of the introduction manual: FMS CRZ PHAS THR LIM.

If it is set to CLB, then the thrust limit in cruise will remain on CLB. If you want it to switch to CRZ, then you have to set the option to CRZ.

Yes CRZ ALT in my CDU is set for FL360

 

and also on my MCP dialed to 36000 as well.

Ok, that's fine but check the second part of my post for the thrust limit in cruise (the CLB/CRZ displayed on top of the upper EICAS).

Thanks a lot Matthew, I really appreciate that. I'm not really doing anything different when programming the CDU before flight. When I use X-Plane 10's FlightFactor 777, it doesn't give me problems. the CDU will automatically switch from CLB to CRZ after it reacher T/C. But I'm not sure why it's not doing this in PMDG's 777.

 

I've looked at page 83 of the introduction manual and couldn't find anything related to this.

 

 

I'm referring to the status display in the EICAS... where it says CLB on the top... that should switch to CRZ after your plane hit's T/C but mine remains in CLB forever.

Thanks a lot Matthew, I really appreciate that. I'm not really doing anything different when programming the CDU before flight. When I use X-Plane 10's FlightFactor 777, it doesn't give me problems. the CDU will automatically switch from CLB to CRZ after it reacher T/C. But I'm not sure why it's not doing this in PMDG's 777.

 

I've looked at page 83 of the introduction manual and couldn't find anything related to this.

 

 

I'm referring to the status display in the EICAS... where it says CLB on the top... that should switch to CRZ after your plane hit's T/C but mine remains in CLB forever.

Yes, the thrust limiting carrots on the EICAS displays are an airline option.

You can set that through the CDU in the display options which is under the aircraft section.

 

It's there because if for whatever reason you got a huge wind shift that killed your performance while in cruise, if you have the option for a CRZ setting, then I would assume that the A/T will max out thrust at the CRZ setting. However, if you like the CLB setting, you will have more available thrust to use in the aforementioned wind shift example.

 

If you are flying at higher altitudes for your given weight in cruise and you're also flying slow to save fuel or for whatever other reasons you choose, you may not have enough thrust in CRZ limit mode to get your speed back. That would force you to have to descend to get your speed back.

 

Like I said, that's what makes sense. I don't exactly know how if the A/T would truly be limited with the CRZ limit or if there's an override within the A/T logic.

All the settings and options in the sections PMDG setup and FS options are not part of the real CDU but the way PMDG allows user to set up aircraft configurations. The option between thrust limit CRZ/CLB in cruise is not accessible to pilots in real life if I'm not wrong.

However, even if your aircraft is configured with CRZ thrust limit in cruise, then you still have the option to "override" temporary that limit by selecting a higher thrust limit by pressing the INIT REF then select INDEX > THRUST LIM which is accessible to pilots in flight.

That was it, thanks so much guys. Which mode would you recommend though? Leaving it set to CLB or CRZ?

 

When would you pick one or the other? Seems like setting it to CRZ would be better, since it will auto switch to CRZ mode once you hit T/C. Can't really see a reason to leave it at CLB, wouldn't that waste a lot of fuel?

All the settings and options in the sections PMDG setup and FS options are not part of the real CDU but the way PMDG allows user to set up aircraft configurations. The option between thrust limit CRZ/CLB in cruise is not accessible to pilots in real life if I'm not wrong.

However, even if your aircraft is configured with CRZ thrust limit in cruise, then you still have the option to "override" temporary that limit by selecting a higher thrust limit by pressing the INIT REF then select INDEX > THRUST LIM which is accessible to pilots in flight.

  

That was it, thanks so much guys. Which mode would you recommend though? Leaving it set to CLB or CRZ?

 

When would you pick one or the other? Seems like setting it to CRZ would be better, since it will auto switch to CRZ mode once you hit T/C. Can't really see a reason to leave it at CLB, wouldn't that waste a lot of fuel?

I totally forgot about manually selecting the thrust limits within the CDU.

 

Good call!

 

As for why you would want it; I'm sure it goes back to what I said before about flying high and slow and having the thrust immediately available to you. As for fuel consumption, it wouldn't change a thing. Remember, it's only a limit. When in cruise, the A/T will maintain the same thrust setting needed for the VNAV speed regardless of what LIMIT is shown on the EICAS.

I think that in most situations it would make no difference as I have rarely seen the thrust going up to the CRZ thrust limit in cruise (except during step climb of course).
I know that it is mainly a company's choice so it depends on the airline (the livery) you fly for (it is part of the configurations of the liveries).

So I would say it is up to you. Now I"m not commercial pilot, so I cannot give a professional advise.