Hello People,

 

Has anyone experienced this issue....

In the PMDG 777-300, when flying through bad weather (WRX+T), flying inside the pink-ish areas, you could at 300 KTS and suddenly lots of expected turbulences but the speed is dropping dramatically to stall limits....on Autopilot.

 

I had to disengage the autopilot and try get around the situation.

 

Is this normal ?

 

To reproduce, ASN, search for area with rain, place the plane on runway and take off (autopilot engaged) fly throught the bad weather...

 

Thanks,

Regis Biassala

 

 

Has anyone experienced this issue....
In the PMDG 777-300, when flying through bad weather (WRX+T), flying inside the pink-ish areas, you could at 300 KTS and suddenly lots of expected turbulences but the speed is dropping dramatically to stall limits....on Autopilot.
 
I had to disengage the autopilot and try get around the situation.
 
Is this normal ?

 

Hi Regis,

 

I think we can find your answer by thinking the issue over a little more together:

 

Weather radar is installed on aircraft so that pilots can:

1. Find weather and fly through it; or
2. Avoid potentially dangerous weather?

The answer to the above being #2, why might the pilot want to avoid said potentially dangerous weather?

 

The answer to this, of course, is that said weather exerts all kinds of forces on the aircraft that could cause damage to the aircraft, or put it in overspeed or stall situations (also potentially causing damage).  So, if real world crews intentionally avoid weather, why would we assume that an autopilot - modeled to be realistic - would also be expected to remain stable in unrealistic conditions (unrealistic in the sense that no crewmember would intentionally fly through these conditions)?

 

The answer to your question, of course, is that we shouldn't expect the autopilot to behave perfectly in very poor weather.  Pilot resolution to the matter is to avoid these cells of weather (as the real crews do), but if a pilot were to find him- or herself in poor weather and the AP or AT is not behaving as you believe it should, take over.

 

...that's why there are still people up front.  :wink:

 

 

 

Thunderstorms are no joke:

Thunderstorm ripped this plane apart: http://en.wikipedia.org/wiki/Capital_Airlines_Flight_75

Thunderstorm (more specifically a microburst from one) slammed this plane into the ground: http://en.wikipedia.org/wiki/Delta_Air_Lines_Flight_191

Thunderstorm caused approach instability and the resulting rain reduced braking action.  Note the giant red cell over the airport in the video: http://en.wikipedia.org/wiki/American_Airlines_Flight_1420

 

Finally:

From the USAF Weather Handbook:

WARNING: When you fly through a thunderstorm, the hazards that face you are extreme.  You will be betting the aircraft, your life, and the lives of your crewmembers on the forces of nature.  This must be the only remaining alternative!

 

...surely nobody expects the autopilot to just take all of that in stride. 

 

 

we shouldn't expect the autopilot to behave perfectly in very poor weather

 

Or, Just that.

Or, Just that.

 

haha...but now I have a novel to refer everyone to.

 

Some of us were taking bets on how long it would take before people brought up this topic, actually.  I'm surprised it took this long.

I flew directly into Hurricane EpicPwnage and the autopilot couldn't handle the 4G turbulence or the 175kt gusts! Why does PMDG make this happen! lolz.

Thanks and I kind of expected your answers......-

We all have tried to see how the new radar is working.....-

 

Thanks guys. lol

 

Regis