Classic ‘Q/coffin corner’ scenario as shown in that illustration.
Illustration lists @ 2:11 a possible “deep stall” but my understanding of a deep stall is that it peculiar to T-Tail designs - like the MD-80 and the B-727.
But my Vne is a mere 128KIAS and we never get close. Why waste the gas? (have to look at that placard again) .
Q corner puts the nose down, and deep stall keeps you nose up. .... on PowerPoint anyways; reality I have no clue. So I dunno. Never flown or trained to fly a swept wing fast mover.
Let's nip it in the bud right now and stop using that phrase, shall we?
Deep stall is only possible with T-type tailplane.
The difference twixt “light and heavy” is mass; and how the aircraft reacts to pilot control inputs. In aircraft you and I fly “mass” is a minor factor as drag/airflow and relative attitude largely overmaster the effects of mass. >PS