Anyone else notice that about 10nm prior to descent in P DES the aircraft accelerates to M0.82 or so from .79 before TOD?  In real life it does not do that.

Heya!

Do you have a specific route this happens on, or always? We had a report like this before, but I was never able to replicate it 😕

When are you arming P DES?

Its consistent.  I arm P.DES between 20-30nm prior to T/D, although ive done it earlier just to see if it makes a difference.  I believe it is related to any STAR that has a 280KT constraint.  It seems the aircraft will speed up to that prior to T/D when in actuality it should descend at the selected mach number and hold at the speed constraint once it reaches it in the descent.