THR IDLE /OP DES (same as flight level change in the boeing, SPEED / DES is the same as VNAV) makes it a bus, and the .78 would make it a minibus i would think so a 320?
Now Metro if you can land one from 15nm 5000' and 250kts straight in your a far better driver than I. Unless these minibuses slow and go down a lot better than their larger cousins. A 330/340 would need to be 20nm min to make that work, most would stick to 25nm.
I do it like nosegear but use the 4 times table to 10000 and then swap to the 3 times table with adjustment for speed, if at 250kts would add 5nm if 210kts and flap1 would add 3nm, if 180kts flap 2 would stay on the 3 times profile.
The Bus FMC uses a level segment to slow down, so to fly a continuous descent approach its profile is not accurate in the later parts of the descent.