Originally Posted by
hans brinker
Have you compared fuel flow for both when THR IDLE is displayed? If the FF is the same, the descent rate has to be the same for the same speed.
I don't know whether it's true now because lot of changes take place. Previously managed descent thrust idle fuel flow was at anti ice on fuel flow to keep predictions accurate should anti ice be required. OP DES was normal idle. That's why the difference.