Hello.

When i descending altitude and set V/s to let's say "-1800ft" 777 still oscillating beetwen -1500 and -2000ft. Aircraft still moving he's nose up and down like on the rollercoster, and the green line on MCD is also still moving up and down. Is this a normal behaviour of this plane or i just something miss in manual.pdf. I'm using OPUS software but when it's of and weather is from FSX, plane have just same bahaviour.

 

Best regards.

Łukasz Musioł

Does this happen on vnav and level change as well? I have opus and it does not give me problems with this plane.

On Level Change - yes, but on vnav i just checked and there is no problem

I have this issue as well. Did a short flight with no weather engines. Just had the sim running and clear weather in FSX.

No it is not normal and I suspect this is something to do with your weather engine. 

 

Have you disabled the wind turbulence and effects in FSX? And do you have a registered copy of FSUIPC?

No it is not normal and I suspect this is something to do with your weather engine. 

 

Have you disabled the wind turbulence and effects in FSX? And do you have a registered copy of FSUIPC?

My PC hang up when i wrote this topic so there is exactly same topic with more answers.

I wrote to Moderator to remove this one.

Second topic: http://forum.avsim.net/topic/421119-descending-problem/

No it is not normal and I suspect this is something to do with your weather engine. 

 

Have you disabled the wind turbulence and effects in FSX? And do you have a registered copy of FSUIPC?

Yes i have registered version of FSUIPC and yes my turbulence in FSX is off.

Guys, remember that there are two different VNAV modes that the 777 uses (explained in the tutorial, if you'd done it):

 

1. Idle (optimal) path - sees the first altitude restriction and sets a descent point (T/D) prior to that, to be at that altitude using flight idle and pitch to maintain speed.  This is a pitch for speed mode.
2. Geometric path - sees the first altitude restriction and subsequent altitude restrictions and calculates a path utilizing a certain vertical speed and thrust to maintain speed.

In case 1, above, you will see variation in vertical speed.

In case 2, above, you will not see variation in vertical speed (or if you do, it will be minimal).

In the case you are using FL CH, you will see variation in vertical speed because the aircraft is using pitch to maintain speed.  If it's fast, it will decrease pitch; and if it's slow, it will increase pitch.

 

Computers are never perfect.  You will never set 1500 and have it hit 1500, exactly, 100% of the time.

 

What you're seeing it probably the interaction of your weather program with the aircraft.

Say Kyle, nice clear explanation of the issue, was wondering myself.  Thanks.

I am consistently finding myself above the glideslope after my STAR. I have tried speed intervention to set a faster descent speed thus getting a faster descent rate but I have a feeling this isn't how the pros do it. Also, I know that unlike the NGX the T7 doesn't automatically slow itself to approach speed. Should this be done with speed intervention, or by manually entering the desired speed at each waypoint into the FMC? I find that when I try speed intervention to slow the plane to the desired speed I then sacrifice my descent path, therefore ending up too high when I get to final. 

 

 

Should this be done with speed intervention

 

Yes.

 

 

 

or by manually entering the desired speed at each waypoint into the FMC?

 

While I won't say 'no,' I'd say it's more proper to do the above.  There's no point in tying yourself to a particular point in space for a speed reduction.  That requires more work anyway...

 

 

 

I find that when I try speed intervention to slow the plane to the desired speed I then sacrifice my descent path, therefore ending up too high when I get to final. 

 

Don't be a slave to VNAV.

 

There are other AP modes there for a reason  :wink:

 

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