Originally Posted by
JALPak
it’s a mid day HND-LAX return
That may be so, but as far as I know, the Japanese government must approve (or build into the bilateral slot agreement) the right for airlines to mix daytime and nighttime slots. I remember reading this being a specific condition with Indonesia's allocations. GA held 2 slots, one for each time of day, but dedicated both CGK and DPS either a daytime outbound and nighttime inbound or vice versa. This needed to be built into the bilateral and not something the airline could just do on its own.
But in Indonesia's case, an evening slot was available to GA anyway. In the US case, AA is asking for a slot that's not technically subject to the current bilateral allocation... theoretically, AA would need to swap the half of the slot with HA and get permission from the Japanese government.
If I'm misremembering something, please feel free to correct me.