February 17, 201412 yr As you can see from the attached screenshot, the MD-11 has stopped descending at FL230 prior to BRBBQ waypoint even though it should be below FL230 at BRBBQ. It did the same thing at SAUCC even though it was entered as 280/-26000. It crossed SAUCC at FL260. That how the magenta path got buried in the indicator on the right side of the ND. About 15 seconds after crossing BRBBQ the plane started to descend at 3500 fpm but it never caught up to the path until I went to a V/S of 4500 fpm with the speedbrakes extended. Needless to say there was no way I was at 250 at BEERT. Does anyone see something indicating why the plane is crossing these waypoints at the FL it should be below? Thank you Michael Cubine Michael Cubine
February 17, 201412 yr This is a known problem. The PMDG MD-11 doesn't seem to be able to handle "at or below" constraints and treats them as "at" constraints. Workaround: Delete the "at or below" and see what the FMC calculates. If its above, the use the "at or below" constraint. If its below then keep the calculated value. Jan-Paul
February 18, 201412 yr Author This is a known problem. The PMDG MD-11 doesn't seem to be able to handle "at or below" constraints and treats them as "at" constraints. Workaround: Delete the "at or below" and see what the FMC calculates. If its above, the use the "at or below" constraint. If its below then keep the calculated value. Jan-Paul Thank you for the information. If the FMC calculated altitude value is above I am entering an specific altitude that is below the waypoint rather than "at or below" constraint. Instead of 280/-26000 and 280/-23000 I am entering 280/25000 and 280/22000. Thank you Michael Cubine Michael Cubine
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