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Stephan Koenig

Odd A/T behaviour in poot weather conditions

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I have an issue with the PMDG 777. The following scenario is given:

 

- Poor bumpy weather

- In approach for Runway X

- Approach type is ILS

- Headwind (slightly from cross) is 8 kts, non variable.

- VRef according to the FMC is 149, 154 set in MCP Window

- A/T Mode is SPD

- A/T override is set to "In HOLD only"

- According to ActiveSky Next, for the approach no gusts are reported

- Remaining fuel is 10.8 tons on MAX Payload (777-300ER)

 

My Sim:

 

- Windows 10

- Prepar3D V3

- Latest PMDG 777 version

- ActiveSky Next

- Flight Controls are a Saitek X52 joystick and quadrant.

 

Now what happens:

 

The speed is going down to the yellow band, if I don't disconnect A/T, it goes into stall, while the A/T doesn't even try to spool the engines up to maintain the selected speed. I had that behaviour in FSX as well as in P3D. However, I wanna make sure it's not my fault somewhere before I call it a bug. Anyone else experiencing this?

 

I've noticed, I've never experienced this in calm weather situations.

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A case of your the pilot in control. 

If the AT is having problems due to bad weather/bad wind. Turn it off and manage the trust yourself. The NG can be the same sometimes, take control and all is good.

 

Never had it in calm weather.

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I don't really agree with that. The point is that A/T doesn't even try to spool up. It's not the case it tries, but fails, it does not try at all....

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I cannot say with out seeing it your end, but if the wind is gusting badly the AT one spit second want to advance and another split second wants to retard. Ive had problems with the NG in bad weather, its like it cannot make it mind up. I see it increasing thrust it does not need or speed starts to drop.

 

But it's rare and never in normal weather. A time when us humans are better than a cpu.

 

If its doing that in normal calm weather sent PMDG a ticket.

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I also have issues with the A/T as i just had a forum-post on it myself. 

 

But you did described it much better. 

 

Its feeling like its spooling up to slow. even when im 10kts below my vref its not reacting fast. its just slowly increasing the throttle, but its to slow so its often resulting in getting the low airspeed warning.

So for me I have to do the landings more often with A/T disconnected than connected.

 

Tom Stian Bjerk

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Something to consider are turbulence settings in ASN. I believe any settings over 50% generate an unrealistic amount of turbulence. Wake turbulence can be set to 0% or none. A plane in the hold short position for the runway you are landing on will generate wake turbulence that will effect your aircraft. Very unrealistic.

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Ditto Michael. The simulation is producing very unrealistic gust conditions, there's even a section in the introduction that discusses this as well as an adjustment you can make to the throttle response dampening to compensate as you wish.

 

All my ASN turbulence/wind shift settings are at 25%.

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