PMDG777 autothrottle question

[noahweber]

Hello,

 

I just purchased the PMDG777 and am having a little bit of trouble with the autothrottle. I cannot tell if I am overlooking something or if something glitchy is happening. Any input would be appreciated.

 

Basically I cannot get the autothrottle to control speed without also engaging the autopilot. The A/T light is on, but the aircraft will accelerate right through the speed selected in the IAS window. If A/P is engaged in a pitch mode like VNAV, the autothrottle seems to meet the speed targets perfectly.

 

Another way to frame this question might be, what would be the correct A/T configuration for an otherwise manual approach? How can I get the plane to hold an assigned airspeed without other A/P modes engaged?

 

Ultimately I'm wondering how I can use A/T to control speed during landing while still flying by hand.

 

Thanks!

 

-Noah

[mgh]

Did you study the PMDG manual closely enough?

[alexzar14]

On take off the AT kicks in only when the AP is engaged until then you control the speed with your yoke following the FD.

On approach, you "off" the AP (I have a button assigned to yoke) but the AT will still be "on", holding the ref. speed or whatever you set, then offs itself on touch down. Kinda like that. You can ask this on pmdg forum, lot's of gurus there taught me lots of things. Actually first you need to read and watch tutorials on youtube, then ask pmdg otherwise they will get angry at you )))

[noahweber]

On take off the AT kicks in only when the AP is engaged until then you control the speed with your yoke following the FD.

On approach, you "off" the AP (I have a button assigned to yoke) but the AT will still be "on", holding the ref. speed or whatever you set, then offs itself on touch down. Kinda like that. You can ask this on pmdg forum, lot's of gurus there taught me lots of things. Actually first you need to read and watch tutorials on youtube, then ask pmdg otherwise they will get angry at you )))

 

 

Thanks a lot for this answer. I am aware of how touchy people can be when it comes to offering assistance on these matters. I might offer the post prior to yours as a case in point.

 

For the record, I did read the manual. I also flew the tutorial... twice. I even watched videos on YouTube AND put hundreds of hours in on the NGX. The scenario I described in the OP was one I had not yet encountered in my studies, so I came here.

 

As it turns out, I think the problem is with my Saitek panels confusing the autothrottle, so you can see why it wasn't a situation that would appear in the manual.

 

Anyways, thank you again for the helpful response.

 

-Noah

[alexzar14]

oh I see what the question was. If you never engaged the AP, the AT won't control the speed even if it is "on". I assume you had the AP "on" during some stage of flight, then disengaged it and had no longer functional AT? Normally disengaging the AP does not "off" the AT, it should still be controlling the speed. Assuming you disengage AP via assigned function and not via the white bar on the AP panel. Cannot disengage by pulling on the white bar as said by PMDG.

[noahweber]

I assume you had the AP "on" during some stage of flight, then disengaged it and had no longer functional AT?

 

Yes, this is the case.

 

When I would disengage the A/P and take over the controls I found the A/T light would stay on, but the aircraft would not adhere to the speed that was set in the IAS window.

 

I am still having inconsistent results with this. Disengaging the Saitek panels helped at first, but I still think I am missing something because occasionally the engines act like they have a mind of their own. Almost like A/T is ON, but not listening to me!

 

I really do appreciate any thoughts on this. I can't find anything in either FCOM about this exact A/T behavior.

 

-Noah

[alexzar14]

How did you disengage the AP? what did you press? Can't pull on the white bar (it disconnects the power feed as I was explained). You need to assign a function to a button, then click it twice to off the AP (2nd time to kill the warning sound). Try that, should work.

[noahweber]

How did you disengage the AP? what did you press? Can't pull on the white bar (it disconnects the power feed as I was explained). You need to assign a function to a button, then click it twice to off the AP (2nd time to kill the warning sound). Try that, should work.

 

I think I've done it both ways, which probably explains why it has worked some times and not others. I will make sure not to hit the bar and see what happens next time.

 

Thanks again!

 

-Noah

[noahweber]

Sure enough, I missed the part about the separate command for disconnecting the autopilot. I reassigned a button on my yoke to CTRL+SHIFT+Z and everything is good.

 

Thanks for being patient with me.

 

Best,

 

-Noah