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joolsd

Strange climbing issues when wanting to descend?

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I am running P3D 3.1 (have yet to upgrade to 3.2) Using Active Sky Next.

 

This is from memory so forgive me for the sketchy testiment.

I had a really strange problem when trying to descend into LFRS. Initially I was descending VNAV, from something like FL240 down to FL080.

However the nose of the AC seem to pitch up. Ok I thought this is weird..not seen this happen before. So I turned off the CMDA and tried flying level. I tried to trim and get the AC into a controlled level flight. Then I thought ok everything is ok to switch the AP back on. I thought why not go into V/S and descend down to 5000f. (By this time the airport was getting nearer.) This seems like a good mode for the final leg of the flight. But again the nose is pitching up. What the hell is going on?  It was a nose up, low speed development.

 

I had Active Sky running, with Ezdok running. There seemed to be a lot of turbulance, which looked great with Ezdok working well. But it was disconcerting with this pitch problem happening.

 

Is this some sort of oversight on my part (user error)? Or is it Icing effects generated, or a meteorological effect of some sort?

 

On the way out of EGKK the AC climbed very aggressively as well..I think something wasn't right about this flight...but I would like to know what was wrong about it?

 

The landing wasn't great, it was a VOR Approach into Runway 21, so no dependency on the ILS.

 

Let me know your thoughts?

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None of my ASN settings for turbulence or shear effects have the sliders higher than 25%.  That's the first thought that comes to mind.

 

A pitch up movement by itself is not a problem, what else is happening? Check your FMA to see what modes you are in, perhaps it shifted from VNAV PATH to VNAV SPD and pitched up to slow down.  You're the pilot, and you get to decide how you are going to manage your speed/energy in a descent. I'll often shift to V/S pitch mode to control my descent and speed if she kicks into VNAV SPD mode, just depends on what is ahead of us in the descent. There might be a good reason to put the brakes on or maybe not.. gotta use your judgement and stay ahead of the plane.

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Trim axis on your hardware?

 

The hand flying stopped the problem..I don't think it was that.

 

There are a couple of things that could be wrong.

 

I did noticed that in the altitude fixes in LEGS page was where the problem may of been. There was a sudden jump in altitude, highlighted in red, which seemed to suggest going back up was where the problem came from.  I noticed it, but then got distracted by something else, so didn't return to it.

 

Would putting in the wrong TAT in the PERF page cause this problem?

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Would putting in the wrong TAT in the PERF page cause this problem?

The average OAT for the flight is entered on LSK4 not the TAT. Assuming you are referring to ACT PERF INIT page.

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The average OAT for the flight is entered on LSK4 not the TAT. Assuming you are referring to ACT PERF INIT page.

 

Sorry that is what I meant, the OAT, in the PERF page.

 

 

None of my ASN settings for turbulence or shear effects have the sliders higher than 25%.  That's the first thought that comes to mind.

 

A pitch up movement by itself is not a problem, what else is happening? Check your FMA to see what modes you are in, perhaps it shifted from VNAV PATH to VNAV SPD and pitched up to slow down.  You're the pilot, and you get to decide how you are going to manage your speed/energy in a descent. I'll often shift to V/S pitch mode to control my descent and speed if she kicks into VNAV SPD mode, just depends on what is ahead of us in the descent. There might be a good reason to put the brakes on or maybe not.. gotta use your judgement and stay ahead of the plane.

 

The ASN effects can be a little over the top. I may try turning it down.

 

I think I will have to do another flight, also checking the trim axis, to eliminate any problems. 

 

I do suspect that the rogue altitude in the LEGS page may of mean the problem so will look at that as well.

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I did the flight again and things were a lot better with ASN turned down.

 

The only strange thing that happened was the AP switching its self off, for some reason. And started descending, but I managed to re-engage it and it seemed to behave again. I managed to fly V/S into a VOR type approach into LFRS RWY21. And the other strange thing about this airport is the bumpy runway, so the NGX seemed to be running over stones.

 

I think with the last flight I forgot to put a "-" in front of the 17 in the PERF INIT section so that may of confused the FMC.

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