The crop dusting pilots on here could teach you a few things about HV curve and what's possible as they are flying in it all day long
Of course we all know that there's no problem flying in 'the shaded areas', much like flying over the sea beside the cliffs … until the donkey stops that is!
That is the moment when the shaded parts of the curve or statements like "within autorotative distance from land" come into play
Which is why we will read things in manuals, such as;
Use of Chart:
Caution:
Observe the cross−hatched regions of the Height Velocity Diagram.
These represent airspeed/altitude combinations from which a
successful autorotation landing would be difficult to perform.
Operation within the cross−hatched area is not prohibited, but
should be avoided.
Dance with lady luck too often and eventually she'll step on your toes
