There's never full access on the entire flight going across the ocean.
Because remember this?
On a recent international United flight from San Francisco to Beijing, though, [reader Matt Schrader's] satellite coverage dropped about halfway across some Arctic tundras. “Right around the international dateline!” he emailed me, upset that he had paid for the whole flight. “I guess tomorrow doesn’t have satellite internet.”
Good to remember before paying for a full $19 pass (six hours) for only three or four hours. Sigh.