Incorrect VNAV constraint behavior

[timc]

Since the new version with the PW engines, it does not appear to be obeying VNAV constraints correctly.  For example with an AT OR BELOW FL230 and AT OR ABOVE FL190 it will level off at FL230.  This was using a flightplan from SimBrief as follow KPHX/25R N0464F340 KEENS3 WLVRN DCT ESTWD HLYWD1 KLAX/06L using the BRUEN2 arrival at waypoint TRUBL

[unhinged_aviator]

Works for me. Flown several legs already.

Fly another route and see what happens.

[MarcusVT]

I have the same feeling. It's always getting high and fast for approach. I'm disengaging A/T when entering APP procedure and also selecting AT, instead of AT or ABOVE, at altitude constraints for final approach fixes.

[Crabby]

You do realize that FL230 is at or below FL230 and at or above FL190.  Your description of the behavior is not a problem.  Looks like you expected it to do something else.  Not only is the plane looking to hit constraints, but it is calculating the path for the next constraint.  I flew that arrival, and it did what was expected. 

[ROMAN78]

Exactly I did what it was supposed to do. You can also manually hard select a specific altitude between the two altitudes. However you observed normal behavior.

[timc]

This problem has now been fixed.

[rlw9sr]

FWIW--With the latest update (~ 2 weeks ago), the aircraft blows through ALL altitude constraints on the DP/SID for EGLL 27R.  This occurs with the altitude constraints set as "AT' rather than "AT+". 

[LukeFF]

3 hours ago, rlw9sr said:

FWIW--With the latest update (~ 2 weeks ago), the aircraft blows through ALL altitude constraints on the DP/SID for EGLL 27R.  This occurs with the altitude constraints set as "AT' rather than "AT+". 

Nothing wrong with that - its flight computer doesn't respect departure restrictions in reality. 

Edited April 23 by LukeFF

[rlw9sr]

Thanks--I did not know that--

[ab145]

VNAV is definately messed up. If you edit the descent constraint at FL100, even though the FMC shows the speeds updated to the new speeds, the speed set by the autopilot is still set to 250, at least until the first WP after FL100. I already manually set the speed to 230, so not sure if the FMC updated the speeds after the fix or not.

 

[Crabby]

43 minutes ago, ab145 said:

VNAV is definately messed up. If you edit the descent constraint at FL100, even though the FMC shows the speeds updated to the new speeds, the speed set by the autopilot is still set to 250, at least until the first WP after FL100. I already manually set the speed to 230, so not sure if the FMC updated the speeds after the fix or not.

 

If you can see the speed in the window and not dashes ---, then you are controlling the speed, and you would have to dial it back and follow the speed limits from charts or what you set.