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Hi,

 

I've had this happen twice to me already, and it has also happened to a friend of mine.  I use ActiveSky 2012, and I am flying through bad weather, usually a thunderstorm, at cruise.  I then get a message saying "Ice Detected", so I turn on the anti-ice, and the warning goes out.  But then, moments later, I will start to lose altitude, and won't be able to hold speed, even at full power.  I'm wondering if the conflict is with ActiveSky.  Sorry if this has been solved already, but I want to get to the bottom of it.

 

Thanks,

 

Ryan

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My first thought would be... Why are you flying through a thunderstorm?

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Ryan, does your indicated speed drop to really (ridiculously) low values? Does the IAS recover after so and so many seconds?

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My first thought would be... Why are you flying through a thunderstorm?

 

Usually it isn't even through the thunderstorm, it's near it, and I'm just getting severe icing and turbulence from it.  Still haven't figured out how to deviate for weather

 

Ryan, does your indicated speed drop to really (ridiculously) low values? Does the IAS recover after so and so many seconds?

 

It drops, and barely stays over stall speed, but it never recovers.  It sounds like it would be icing, but the warning goes away...

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And it's happening again now.  Thunderstorms over Ireland.  Can't hold speed, even with full throttle.  I even put anti ice on before I was even close to the clouds, and I still am not really going through any.  This is really annoying 

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If you are too high, the anti-ice reduces engine thrust, so this will happen.  The exact critical height would of course depend upon many factors.  But in a recent Mayday episode this exact issue caused a fatal plane crash.

 

Incidentally, this is why anti-ice stays off when not needed.

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Yeah, I think I'm getting the same thing in the J41. Go into AS2012's Options pane and I believe there is a setting for icing (not certain as I'm not at home right now). Reduce that down a bunch and see if that helps. It could be AS is able to deliver a whole lot more icing than what the airplane can handle. If you reduce it by 70% or so and it helps or fixes the problem, then you'd be able to keep the effects but the airplane would be able to keep up with it. Worst case scenario, reduce it to zero and that should get rid of it entirely.

 

Let me know if you try that and if it works.

 

Glenn

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Yeah, I think I'm getting the same thing in the J41. Go into AS2012's Options pane and I believe there is a setting for icing (not certain as I'm not at home right now). Reduce that down a bunch and see if that helps. It could be AS is able to deliver a whole lot more icing than what the airplane can handle. If you reduce it by 70% or so and it helps or fixes the problem, then you'd be able to keep the effects but the airplane would be able to keep up with it. Worst case scenario, reduce it to zero and that should get rid of it entirely.

 

Let me know if you try that and if it works.

 

Glenn

 

Thanks.  It was a good idea, and I reduced it to 20% (it was under cloud icing), but it didn't work.  I definitely thought that that one would work.

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Nuts. Take it right to zero, and look for ALL sliders related to icing. If this doesn't work, we have a problem. I wonder if there is anything in the FSX sliders that account for icing? Might look under a/c realism settings just in case. Also try in the FSX weather window. It should be overridden by AS, but you never know.

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Nuts. Take it right to zero, and look for ALL sliders related to icing. If this doesn't work, we have a problem. I wonder if there is anything in the FSX sliders that account for icing? Might look under a/c realism settings just in case. Also try in the FSX weather window. It should be overridden by AS, but you never know.

 

I put them down to 0, and I still could barely climb.  And the MD-11 said that ice was still being detected.  Tried the FSX weather didn't work.  I'm baffled

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I use AS2012 and the MD-11 and don't have any of those problems.  My ice setting is at MAX 100%.  It sounds to me like operator error.  The anti-icing should be AUTO and not require any pilot input.  It sounds like you are turning the anti-icing off. 

 

Billy Bluestar

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I would look at trim settings before TO. Or the COG is off? What is the angle its trying to fly at?

Never had this issue but I use opus. I've had the TAT go way up where I couldn't climb anymore but I could maintain speed.

The MD-11 has the low speed protection system that should kick in. Providing your flaps are where they should be it should be able to handle it.

 

 

 

 

 

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As I said in the first post, I get a warning saying there is ice detected, so I turn the ant-ice ON, and it goes away, but I still can't maintain altitude and airspeed.  Eventually, it would go in and out of protection mode, put still wouldn't fully recover.  I think that it was the combination of the cloud icing, headwinds and turbulence that did it, because I am now flying in clear skies, having no issues

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Yeah, this is a puzzle for sure. Headwinds and turbulence shouldn't have any effect on IAS, especially in cruise mode. For sure something is up here. Last night I was at 15K in the J41 and the IAS dropped (slowly) to 160 (and still descending). Temps were pretty much normal (-11C) for that altitude and time of year, so it wasn't that (it didn't change appreciably throughout the flight anyway). I'll see if I can reproduce this myself, but it won't be for a couple of nights I'm afraid. See if you can gather anymore data on it in the mean time and we can compare notes and hopefully come up with something concrete. Back later... .

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Hi,

The same thing happened to me with the AoA training flight from PANC to KMEM with their routing and WX. After about 2 hours the fuel temperature started to get very low and the power was dropping like a stone.I managed to level FL100 and climb again but the same thing started again.I never managed to solve the problem.I redid the same thing on VATSIM and noticed the temperature was not as low as the AoA flight and had no problem in finishing the flight.I would like to know if somebody solved the problem.

 

AlainV

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What fuel type are you using for the flight? If temperatures get too cold, Jet-A will freeze, A1 should handle a bit cooler temperatures (-47 IIRC).

PMDG has modeled this aspect and on the INIT page, there was an option to choose fuel type.

If the fuel gets too close freezing, you should descent to a lower altitude.

EDIT: more info here:

http://forums1.avsim.net/topic/239434-md-11-fuel-freeze/

 

EDIT#2: Just realized that you didn't mention that any of the engines had flamed out. This might not be caused by fuel after all.

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The anti-icing should be AUTO and not require any pilot input.  It sounds like you are turning the anti-icing off. 

 

Billy Bluestar

 

Billy,

Engine and wing anti-ice is NOT automatic on the MD-11! You have to turn it on when required and of course OFF if not required, manually.

Cheers,

Markus

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I've been flying the PMDG MD-11 a couple times a week since it was released along with AS Weather and don't have any problems.  The onlly time I get an icing advisory message on a regular basis is when landing at SLLP. 

 

The "ICE DETECTED" is a message, it is not a Warning. 

 

When the "ICE DETECTED" message is received there is NO input required by the pilot.  

 

Billy Bluestar

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I'll recheck my manual but I have to go with Markus on this one. Anti-ice is always at the pilot's discretion AFAIK because it can have a serious impact on performance, particularly as it uses bleed air from the engines. You can't use anti-ice or de-ice on takeoffs for instance (thus the reason for de-icing bays and different types of de-icing fluids at most northern airports) or you may end up parked in some person's back yard (maybe that should be persons for the MD-11! <LOL>)). It is manually controlled, I'm certain.

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Hi all,

 

The only problem I have experienced has been with fuel icing, flying over Greenland in the winter, not very bright I must admit but that was before I found out about different fuels and the fact the MD11 doesn't have fuel heaters like a Boeing. Ended up with a glider and learning how to restart the engines in flight, very quickly!!

 

Happy flying

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I've had the same exact problem as the original poster, been flying the plane pretty solid the last few years. Can't remember when it happened last, maybe over Ireland during thunderstorms (I'm using AS2012).

 

I suspect it's operator error and am curious if you find anything out.

 

Chris K.

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Hi Guys,

Indeed as JPUUSTININ indicated, if you use A type fuel, it freezes at -42°c, using A1 type fuel protects you towards -47°c

Using A type fuel under long lasting very colf temperaure will get the fuel sticky and engines operation affected and aggravation when getting through/close to CB's.

When programming the FMS, under INITpage get next page twice and set A1 instead of A, you'll be fine.

Kind regards,

Jacques

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This sounds promising about the fuel type situation. Thanks people, that's worth looking into. It won't be my problem with the J41, but quite likely (now) that's a whole different issue. I've been away the last day so haven't had a chance to try it, but hopefully in the next couple of days. To Ryan, if you get it again, check to see what your engine gauges are telling you. N1 or N2 dropping, ITT's dropping, etc.? That might be the giveaway.

 

Thanks again - sounds like this might be it.

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Interesting.  I knew about using Jet A1 for colder regions; never thought it would effect flying around thunderstorms.  I'll have to pay closer attention to my temps next time it happens.  Good advice.

 

Chris K.

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