Originally Posted by
Sidestick_n_Rudder
AFAIK it’s the opposite - descending on a profile, that is too high/too fast and with speed brake uses around twice as much as descending too early and flying a lower speed.
787 VNAV is utterly cr@p. I don’t have any other Boeing experience, but the VNAV (sorry, ‘managed DES’) on A320/330 does a much better job overall - even though It was erring on the conservative side, i.e. normally ended up low/slow.
One thing I’m suspecting is ‘Idle Factor’. At least on the ‘Bus you can change it and it affects the steepness of the calculated path. I actually wonder if it can also be modified on Boeings. Anyone?
At least on pilots’ reach, B737 and B757/767 don't have boxes for “IDLE FACTOR”. I don’t think FMS configuration function offers something like that to our mechanics neither.
I’m not sure about much newer 787.