You never fly over the Pacific Ocean EWR->HKG, and you sometimes don't fly over the Pacific Ocean HKG->EWR either. But yes, they are "Trans-Pacific" flights.

EWR->HKG, you always fly over the Arctic Ocean.
HKG->EWR, most of the time you fly over the northern Pacific, but sometimes you fly over China, Russia, Bering Sea, Alaska, Canada - so you're flying over land 90% of the way.