I was asked to make a 6,000’ crossing restriction once in a Global from F450 or F470. I told BOS ARTCC that I would have be assured of no level on the way down. Idle, M.85/320 and with MAX boards we were over 10,000 fpm down. Cabin never budged up from 4,500’, but the cabin descent rate was pretty good! Lot air has to be pumped in for F510 cert.
gf