Hello to all:

 

I have recently (I believe that after the most recent update) started to experience a dizzying experience with the B777-300 (Interestingly enough, it does not happen in any of the various PMDG or other add-ons I own).

 

At cruise altitude (i.e. FL370) it continuously oscillates with variations of 500-1000 feet and corresponding changes in air speed as the AP tries to compensate for the descents and ascents.

 

It happens with ASE on or off, it happens on-line (VATSIM/IVAO) or off and with either VNAV or ALT HLD selected.

 

It is obviously quite disrupting and, looking at a porpoising screen for a long flight is no fun.

 

I have tried to search the forums, although the search-words I have selected were not very successful.

 

Does anybody else experience this problem? 

 

Thank you!

Roberto

 

 

Does anybody else experience this problem? 

 

Loading the aircraft via the CDU or via an external load manager?

 

Do you have a trim axis assigned to your hardware?

Hi Kyle.

 

I load the aircraft via the CDU (although I truly only change the fuel).

Yes, I have a trim assigned to my SAITEK Pro Yoke.

 

Thx for the lightning speed response!!!

 

Regards,

Roberto

 

 

Yes, I have a trim assigned to my SAITEK Pro Yoke.

 

Disable this assignment and see if it has any effect.

No change

:mad:

Roberto

FL370 is easily above where you want to be in a loaded B77W.  How does FL370 compare with the optimum and maximum altitudes provided by the FMC Cruise page?

Hello Dan:

 

The FL maximum provided by the FMC was FL390. I only had 35% fuel., so I was not that heavy.

 

Thinking as you did, I descended to FL310 en-route and still had the issue.

It was still oscillating (although not with 1000 foot deviations and annoying alerts) on the approach STAR procedure; finally quieted down on short final.

 

I will take the -200 for a "spin" and I will report back.

 

Thank you for your comments.

Roberto 

Roberto, this is not a bug in the aircraft.. it has something to do with your configuration. You said it happens with no weather so that rules out the most common source of a pitch/speed oscillation problem. Oscillations of 1000ft are very wrong, not something minor, which is why Kyle asked about payload/fuel load method. I'm agreeing with him, something may have corrupted the aircraft.cfg file. Do you have any addons, such as TOPCAT, that directly access aircraft weight and balance?

Hello again Dan:

 

I am repeating this morning's flight, step by step, but in the -200 rather than the -300. I have been at FL370 for the last 25 minutes and it is "rock solid". The -300 started to oscillate as it entered the FL300's in the climb.

 

(I should have remembered that I had a beautiful flight two days ago in a freighter .... a  -200  ... duhh)

 

Something obviously got broken in the -300 and I will follow "advice # 2" of one of my kids .... re-install!!

 

(Advice # 1 is ... "close all the windows, then open them again .... that sometimes works" ... ) :-)

 

Thank you for your interest and your advice.

I will report back as soon as I can accomplish all of this.

 

Regards,

Roberto

The uninstall/reinstall trick worked.

Whatever was broken is now fixed.

I am happy.

 

Thank you Kyle and thank you Dan.

Roberto

Using P3DV4.3 and Oscillation ghost came here on the PMDG 777-300ER ....    Unistalled and reinstalled the 300 expansion only and it worked for mee too.....   👺Exorcism was successful 🤣