hikoushi said "The simple answer is that in MOST Pacific airspace (basically everything between the US West Coast all the way out to Japan and down south most of the way to Australia and NZ) no, it is not required."
hikoushi you emphasized "MOST" in capital letters. Are there in fact some areas of the Pacific requiring CPDLC and/or ADS-C?
rsiano poses an interesting question. Is there some simple way to determine what oceanic areas of the world require CPDLC and/or ADS-C?
I see in post #2 None says typically not required. However, a definitive answer would be useful
Hawk