Will not settle on selected altitude

[bradrcfii 3]

The VSI will not settle at zero when the selected altitude is reached.  It wanders above and below the selected altitude by about 40 feet.

 

Any ideas?

 

 

[scandinavian13 5,192]

 

 

Any ideas?

 

Yeah.

 

Life.

 

Updrafts, downdrafts, pressure gradients, and other atmospheric conditions will cause the aircraft to rise and sink, therefore causing indications of vertical speed.

 

I see that you're a CFII.  Isn't I-VSI discussed in instrument ground?

[bradrcfii 3]

Just completed a long flight KIAH to LBAA.  Flew at three different flight levels and tried two different weather programs.  

 

It never settled on the cruise altitued.  Watching it pitch up to a 500 feet per minute climb passing thru the selcted altitude does not look right to me.  On the intermediate altitudes on the way down were fine but not at cruise.

[Paul_Smith 92]

Just completed a long flight KIAH to LBAA.  Flew at three different flight levels and tried two different weather programs.  

 

It never settled on the cruise altitued.  Watching it pitch up to a 500 feet per minute climb passing thru the selcted altitude does not look right to me.  On the intermediate altitudes on the way down were fine but not at cruise.

1) What level of acceleration were you using, higher levels will increase instability.

2) How much was your weather changing?

[scandinavian13 5,192]

 

 

It never settled on the cruise altitued.  Watching it pitch up to a 500 feet per minute climb passing thru the selcted altitude does not look right to me.  On the intermediate altitudes on the way down were fine but not at cruise.

 

hmm...

 

The earlier 40' wandering didn't bother me too much, for the reasons already mentioned, but busting through the altitude at 500fpm is a different story.  Have you tried it without weather entirely (not as a solution, but as a part of the troubleshooting)?  As Paul mentioned, are you using time acceleration when this happens?  Did you set the payload or fuel by any means other than the FMC pages under FS ACTIONS > ?

[bradrcfii 3]

Problem solved.  I discovered my FSX weather was causing problems.  I did not have it turned off completely.  Opus provides a weather theme to select.  Tested and all is well.