Can Seats Be Preassigned?
If your flight is marketed as AA, but on JL metal (i.e. "AA 8499 Operated by Japan Airlines"), the following apply based upon the fare code or booking code for your flight segments:

N - Seats may only be selected at checkin/airport

O - Seats may only be selected at checkin/airport (Confirmed with AA 6/11/17)

Others - Probably can preassign, but please modify this wiki if not

AA Award tickets on JL metal - DO allow seat assignments.

**When inputting a flight number that is a single digit (such as flight 1 from HND-SFO), you must add a leading '0' (zero) when looking up your flight. Failure to do this will result in an error that they can't find your PNR.

If you try to call AA on these fares and select seats, even as an EXP, the agent will be unable to view the seatmap and select seats for you. Your reservation will simply display "--" as the seat selection. Oftentimes these codeshare tickets do not allow JL checkin at T-72 hours, so you may not be able to actually get seats until the airport. You can try online checkin with JL here: http://www.jal.co.jp/en/inter/boarding/quic/

You may find more information here:
Flights from US to Japan
Flights from US to Other Asian Destinations

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Info added on 15th Sept. 2019. As a one world Sapphire, you can select the following business class window seats
From row 5 on the 767, 787 and 772 (excludes rows 1-4 window seats)
From main cabin on the 777W (excludes whole of mini cabin)

As a non-status passenger (or Ruby member), you can only select the following business class window seats
From second row onward of second cabin on the 767, 787 and 772 (excludes all of the forward cabin window seats and first/exit row of main cabin)
From second row onward of main cabin on the 777W (excludes whole of mini cabin and first/exit row of main cabin)

As a OWE, you have unlimited access.

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Which Booking Code Am I In?

If you have not viewed your fare at booking, you can follow the below steps to check your booking code: