According the JAL regulations when flying with an Economy Ticket you have the opportunity to upgrade to Premium Economy for $350 at the airport if seats are available in PE. Does one have to upgrade only at Narita or can one upgrade from any airport when you are flying JAL? As an example BKK/NRT/JFK. Would I be able to upgrade at BKK for the same price or is it only allowed from NRT or would the price be different from BKK? Also, is the upgrade only done when checking in at the airport or can it be done on line within the 24 hour check in window?