"Not logical"
Why?
"The pilot clearly negotiated the high headlands and resultant turbulence of Port Stephens without a problem."
Yes. Not talking about localised turbulence. Talking about mountain waves with rotors.(nb not helicopter rotors)
Great Dividing Range, not high headlands.
If you ever encounter one you will know what I am driving at.
https://www.atsb.gov.au/publications...ve_turbulence/