Auto throttle speed control

[InfinitePotato 1]

Bumptydump. Should I post a new thread to get attention?

[Mike777 163]

 

 

The weather was somewhat turbulent. Not hugely awful, but bumpier than average. Could the TURB MODE be the culprit? I think I should experiment with higher values for it...

 

Hi, Aleksi,

 

It might be caused by unrealistic turbulence.  Do you have "Disable Turbulence and Thermal Effects" checked in Settings>Display>Weather?  What weather program are you using (if any)?

 

The AT/TURB setting also seems to be to reduce wind fluctuations, but I suggest you deal first w/ the above setting and then look at your weather software (if any) to make sure it is not setting high turbulence.

 

Mike

[777simmer 117]

Here's a screenshot of what it did to me today. It doesn't happen on every approach, about half of them maybe, but again, turbulent approach into EDDF and this happened when on glideslope I set my assigned speed from 180 to 160:

 

 

Speed dropped to 145, at which point I lowered flaps to 25 and set speed to 145. A/T didn't respond too quick and the plane accelerated back to 155 before slowing down. I managed to get her down without disconnecting autothrottle, though.

Do you know what triggered the NO AUTOLAND message? and do you get that often?

 

Because you should not.....something is not right with the AFDS system.

 

Do you start your flights from a saved flight or panel state?

If so, then dont....instead, setup a fresh flight from the FSX menu.

Bumptydump. Should I post a new thread to get attention?

A little impatient but at least funny ;-)

[777simmer 117]

By the way, I have started to use turbulence effect a few months ago.

 

So the turbulence option in the FSX menu is ON and I also use OpusFSI live camera to give me VC shake during turbulence.

This is working fine and does not cause any IAS problems at all so far.

 

So I do not think that the IAS problems mentioned here are caused by ASN turbulence.

 

Maybe what you guys are seeing is just an occasional system screw up.

Maybe all you need to do is disnengage and re-engage the AT to reset it?!

 

the other day my AP did not work anymore.....just would not engage.

After I turned both FD off and back on (this resets the real AFDS system as well) the AP worked just fine again.

Things like that can happen.

[InfinitePotato 1]

Hi, Aleksi,

 

It might be caused by unrealistic turbulence.  Do you have "Disable Turbulence and Thermal Effects" checked in Settings>Display>Weather?  What weather program are you using (if any)?

 

The AT/TURB setting also seems to be to reduce wind fluctuations, but I suggest you deal first w/ the above setting and then look at your weather software (if any) to make sure it is not setting high turbulence.

 

Mike

I don't want this to be the solution. FSX air dynamics are dull enough WITH turbulence. Without it flying would surely be like riding along rails. I use ASN, yes, and am aware of the potential issues it might cause. However, I didn't experience these issues with the release version of the 777, and I haven't changed any turbulence settings since then, although ASN has been updated. Don't know if those updates changed anything. 

 

 

Do you know what triggered the NO AUTOLAND message? and do you get that often?

I think I get that everytime I'm at 1400-1500 AGL and not in landing config, so I figured that's why if I have gear down and flaps at least 25 before 1500 AGL, there's no such message.

 

I'll try and reset to A/T when this happens next time. Thanks for the replies

[miguelpp 25]

Hi Alexsi, same problem here. It happened twice. Never before SP1d.

 

 

 

Best.

 

Miquel Egea.

[deckerloyd 0]

I'll weigh in while we're on the subject...

 

For me I occasionally experience two different problems with the same effect:

1) A/T switches to HOLD mode on final and I don't know why. It could be because I have something programmed/configured incorrectly but I don't know what would possibly cause the A/T to switch to HOLD on final; any ideas?

2) A/T mode is on SPD, thrusts reduces to ~50% and never goes back up despite the speed falling through the yellow line.

 

When case #1 occurs I can switch off VNAV and hard-set the speed into the window. Sometimes it takes some tinkering with, and turning A/T off and on again but I can almost always get it back on SPD. But in the time it takes to fix it I've lost altitude and speed and when I'm IFR it messes up my scan and I end up having a crappy approach. 

 

When case #2 occurs I have no choice but to disconnect A/T and make throttle adjustments myself. Turning the A/T back on again doesn't work as it just resets the thrust to the same place it was before I disconnected (~50%). 

 

The only difference is I recall mine happening from the very beginning when I first purchased and installed the T7 on its release date. That however was mainly the HOLD problem and like I said it could be user error.

[Mike777 163]

 

 

1) A/T switches to HOLD mode on final and I don't know why. It could be because I have something programmed/configured incorrectly but I don't know what would possibly cause the A/T to switch to HOLD on final; any ideas?

 

It can happen in LNAV/VNAV if you are very far above the VNAV profile.  I filed a ticket about this but apparently it is normal.  Shutting off the A/P and both FDs should send A/T into SPEED.

 

I found this out on the KJFK Canarsie VOR 13L approach.  It is necessary to fly this approach manually since it involves a low altitude right turn, but I was descending using the GS pip instead of the VNAV pip, A/P off but FDs and LNAV/VNAV still lit.  The results were not pretty.

 

I subsequently experimented on KSFO 28R and if I stayed very high, same thing.  But there VNAV profile and GS are not very far apart.

 

Mike

[777simmer 117]

you should open the speed window on a Vmav approach!

Otherwise the aircraft will automatically slow down or accelerate to the speeds programmed/shown on the LEGs page.........regardless of your flap position!!!

 

So:

While level on the intermediate approach and waiting for Vnav PATH to capture the final approach (you dont have to be level, can also be a descend or whatever, but often you would be level here) push the speed selector and dial in the required speed (for example flaps 5 speed).

 

Do make sure that final is flown with Vnav Path.....not Vnav Spd.

Vnav Path should engage automatically instead of Vnav Spd when on final approach.....if it does not then something is wrong and you have to revert to FPA or VS for final!

 

The other thing about the AT not reacting or reacting too slow sounds like a real problem.....a bug some are having and some not.

Have you guys contacted PMDG per support ticket?

 

Like Kyle I am not a big fan of unistalling/reinstalling things.........but maybe in this case I would give it a shot if PMDG has no solution either.

Make sure you install the PMDG777 with no virus scanner running!

 

Not sure if it matters.....but for OpusFSi I had to share the whole FSX folder and give that folder full read/write rights to everyone. Otherwise OpusFSi can not write weather into FSX....or something like that.

Maybe this helps the PMDG as well......I never read about it......so it is just a thought and easy to try if it helps. Who knows.

If you need instruction for sharing than just let us know.

[jcomm 5,890]

777Simmer,

 

as a real 777 driver, I thought it would be great if you could record a series of tutorials ( youtube ) pretty much like Captn. Peter ( Britjet ) is doing in his "tutorial videos" thread at the Aerowinx PSX forum.

 

Each video gives invaluable information to every sim pilot, like the latest on how to land a 744 in crosswinds ... It would be great to be able to learn from your experience too ! 

[777simmer 117]

I have thought about it, but not everybody has such a great, professional voice like Kyle or a sexy Brittisch accent like Captn Peter, haha.

 

No videos really would not be my strength.

(I think I am much better at face to face teaching.)

 

But for now I will stick to the Forums I think.

 

Thx though :-)

[Julean 12]

Today at an approach to TTCP, I decided to descent rather fast.

From FL 240 to FL13000. I disengaged the autothrottle and did vs -2500 and throttle to Idle, full speedbrakes.

Got the order to go to FL120

It went well

 

Then I reengaged the aut. throt. and VNAV.

But it didnt throttled the engines.. I was manual flying the rest of the way, like flying an B707 :-D

 

All the best

 

Jens

[cagrikartal 8]

Hello pilots,

 

I had update my b777 300ER. During landing To VHHH airport I experienced Some problems with the autothrottle speed controlling. There was Some wind from 230 at 10kts and outliers with 20 Kts something like that. The autothrottle does not follow the input speed limits exactly, this results for me two times in a stall. So I had disabled the autothrottle and used the throttle manually. Did I Anything wrong? Or is that a known problem with the 777? Because I never experienced this error with the 737 ngx.

 

Please tell me your experience about this error

 

Volkan

 

It happened to me as well, its a problem about ASN (If you have it) Service pack. try to fly without the sp1b. thats solved the problem for me. try this or wait for furter sp from hifi to correct this problem.

[777simmer 117]

I usually fly with the OpusFSI weather engine.

 

But recently I have done a couple of flights with self created weather from the FSX weather menu and it seemed the AT was much slower than what I see normally (with Opus).

 

I did not get into severe problems where I had to disconnect the AT but the AT definately looked slugish and allowed both long (timewise) overspeed and underspeed conditions.

 

One thing that could be causing this is FSX turbulence......I have reactivated that FSX option a few months ago and with OpusFSi + OpusFSi live camera, this mode does a good job of simulating camera shake (turbulence).

Maybe the FSX turbulence mode is causing my AT to not know what to do unless OpusFSi is handling the weather calculations? (PMDG recommends FSX turbulence option - off by the way).

 

So it really does seem like weather is playing a part in the slow AT problem that some are having.

 

I suggest trying a flight with the FSX turbulence option - off, and while flying in an FSX default weather theme (like grey and rainy).

[skysurfer 76]

Hi guys, can I ask a question here as well? I may have similar issues and in VHHH as well. 

 

I have strange speed behavior in VHHH as well. The only difference it is during takeoff and initial climb out. All other airports seem to be fine. So I set FMS and MCP as needed. During takeoff roll I see that takeoff thrust is set correctly, N1 readings look normal. Just before V1 or at V1 N1 reading drops by a half and I see/feel speed loss. I have to advance throttle all the way forward up to the limit to continue takeoff. It looks like A/T does not hold the speed. 

 

Even if I made successful takeoff with no power loss it may happen that I will lose speed on climb out. I retract flaps on schedule and at flaps 1 or after flaps retraction she lose speed regardless if I keep hands flying or when I engage the autopilot. Even if the aircraft if stable on climb it begins suddenly lose speed down to min maneuvering speed. I crashed several times. It happens out of VHHH,I have not noticed this anywhere else. No matter how heavy is the aircraft and how much fuel I load, full power takeoff or derated. 

All indications in ND and MCP look normal.

 

Thx for looking.