I am wondering how far in advance does a carrier really know what the exact ship number will be for a specific flight? Last minute substitutions, and MX issues set aside. I know this would depend if a carrier has only one single 777,
I'm aware one would know what the ship number will be, but for carriers like EK, AA/US, JL, LH, BA, or even AS (738) or HA, when is it set? I am unfamiliar with the process that even decides such things, so feel free to explain anything you know as fact, that could help explain how different carriers make this decision.