Between 1985 and 1991 United acquired the Pacific division of PanAm as well as Pan Am's London-European operation and the rights to fly LHR to the US for a total of $1.4B over 6 years (over $3B in today's dollars). That was a hefty price back then. Some of those routes have expired, but United has substantial rights to fly all over the Pacific. I remember seeing a list of all the route authority United has in the Pacific and it is staggering. This might be why Kirby ordered 150 787s. The Narita operation alone at one point was so large there were talks of opening a pilot base there in the 1990s. United had a massive flight attendant base in Narita as well.

The Pacific route authority also included the HNL base and the 747s that were based there. Although United closed the HNL 747 base there is still a Flight Attendant base there and this is why United has more gates in Hawaii than any other airline except Hawaiian. To this day there are United Flight Attendants that are still flying that are Legacy PanAm out of HNL. All of the legacy PanAm pilots retired years ago.