hi folks

 

i have discused this many many time in this forum. I reinstalled every thing ( inculidin complete reinstallation of windows) a few weeks ago. But the problem seems to be back again, What happens is when flying the final approach if the weather is a little turbulant (relatively minor turbulances ) the auto thrust does not responde quickly to speed changes and the speed drops down to yellow bar which disables the autoland. what is more interesting is that even after that auto trust does nothing to get out of yellow  bar.

 

The last time i had this problem i resolved it by reinstalling the ASN without service pack then it seemed to be gone.  I thing there is something wrong about handling when using  the asn.

Not only that. Many times, my airspeed was higher than then the selected one, and thrust doesn't seem to want to reduce. This happens especially on final approach after capturing the glideslope. I have to put the throttle to idle or it will exceed VFE next.

Ali Hoteit

It's not a fault with your installation. Autopilot and autothrottle don't respond too well to turbulence in FSX. PMDG have made improvements, described in the Intro Manual, but you may have to reduce ASN turbulence levels to get things manageable. I use 25% settings rather than the default 100%, which I think is far too much anyway.

 

Also, if speed drifts off target consider taking over manually. You are in control, don't just watch the automatics flounder.

Thanks for your replay... maybe its time to move onto p3d. maybe fsx is not good enough for such a system complexty etc... i have one last question left if you dont mind.

 

Is there anyone suffered from this problem in p3d or in other words, what kind of problems are resolved in p3d that fsx wasnt able to offer any solution ?

Remember that the autoflight system in the real aircraft is not perfect and turbulence may well be too severe for it to cope with accurately. I don't have P3D so I've no idea whether turbulence has been modified in that platform. Rather than switch platforms, the first option is to try reducing ASN turbulence effects. I think they are set high too by default, probably to emphasise the effect rather than replicate the response of a large airliner.

Basically same experience

 

And then what Kevinh said

Remember that the autoflight system in the real aircraft is not perfect and turbulence may well be too severe for it to cope with accurately. I don't have P3D so I've no idea whether turbulence has been modified in that platform. Rather than switch platforms, the first option is to try reducing ASN turbulence effects. I think they are set high too by default, probably to emphasise the effect rather than replicate the response of a large airliner.

 Thats why i ve written ''minor turbulances'' which aircraft's auto thrust system can easily overcome, but you are right in some cases pilots must interfier with thrust levers to get a quicker response.

 

thank you for your suggestions, I'll check those settings tonight to see if it changes anything

 Thats why i ve written ''minor turbulances'' which aircraft's auto thrust system can easily overcome, but you are right in some cases pilots must interfier with thrust levers to get a quicker response.

 

thank you for your suggestions, I'll check those settings tonight to see if it changes anything

 

Please have a look at the intro manual, reference "turbulence."

 

"Minor turbulence" in FSX is hardly that. We include a graph showing the actual forces.

 

 

I use 25% settings rather than the default 100%, which I think is far too much anyway.

 

That's where my turbulence settings are too and it seems to work okay (P3D).

I don't believe it's just the turbulence that is the problem. I was doing a flight from CYUL to CYVR yesterday with the 777-300. I was on ILS26R approach. When It captured the glideslope, it dove down like there's no tomorrow. My speed was 170-180 KIAS and flaps 15 at about 3000 ft asl and 10.0 dme from the rwy. I used flaps 20 right away but it kept diving and diving and was about to exceed the VFE next speed. Not only that, even with all that diving, I was way above the glide path and I had to go around. Winds were steady headwind about 10kts with no turbulence. I have ASN as well.

Ali Hoteit

Presumably you extended the landing gear before G/S capture? If the A/T is not reducing thrust to maintain speed after G/S capture then maybe your throttle hardware is overriding it. Try setting the A/T thrust lever override option in the FMC CDU to NEVER, or try disconnecting your hardware.

 

It's very odd that it gained airspeed and yet still could not maintain the glideslope. What modes are shown on the FMA?

Check the box in the fsx menus that disables turbulence effects on aircraft. an xml file in the main fsx folder, thermal something it is called, has many areas pre programmed with turbulence including most approach paths. I guess to simulate wake and ground turbulence. Better to check the box so only ASN does it. And lower the intensity in the ASN menus, there are many options in there including wind turbulence. And the fsx.cfg file has a turbulence scalar that can be changed to 0.5

Remember this is not the NGX.  The B777 FMS SPD mode should be changed to MCP SPD during approach for speed control.