From that I would say there isn't a whole lot we can do about our PT6's going into beta or reverse all by themselves. None of those guys were selecting beta/reverse in flight. They were reducing power. Follow SL# 172 and hope for the best huh?
I can see your point about not going into ground range in flight Guppy, but I am also not going to operate in ground Idle, I work mostly off a short one way airstrip and If I need power to go around, then I need it right NOW.
It seems that most guys that work in flight idle need to grab a bit of beta on late final. By your reckoning, that is a bad thing, and sure enough the book tells us to not do it. Perhaps we should have our props setup to have less idle thrust?? So that we can operate in flight idle and not need to bring it behind the gate to get a slow short landing.?.?.
