Originally Posted by QRC3288

Yes you can upgrade it, sector by sector. Presumably they'll offer you the cash upgrade from your biz fare class to A (if available) or F (if A is gone). I have never been so lucky to get A on same day cash upgrades and have to pay up for full F.

Depending on your underlying fare class, you could be in for some sticker shock. If you're flying D or I, for example, you can expect to see probably ~4k USD (aka, almost the full value of F the HND round trip) tacked on. There will not be some bargain to be found doing it this way. Fyi, you can do this in advance - aka CX is not going to charge you F class to/from YYZ if only available on the HND sectors. However, where you may be onto something is CX's online booking engine won't let you choose sub fare class, and it may well be it's forcing you into fly J or C class ex YYZ on the longhauls, which is unnecessary. If this is the case, just call CX or a travel agent to get it booked properly. I **think** you should be able to get an I or D fare ex YYZ to HND, and then upfare only the HND sectors, all done well before the flight date.

However, I can never figure out how CX calculates the value of each sector but IME an overwhelming percentage is on the long hauls not the intra Asia connecting sectors. Others can chime in if I'm off base. But I'm assuming you're hoping to buy some discounted biz fare ex Toronto, in which case the HND sector "value" is going to be low, meaning the upfare to F will probably be very close to full fare F for those sectors. If you are actually intending to buy J or C fare ex YYZ to HND, then I think you're just confused - CX isn't charging you F on the non-F sectors!

What are ex YYZ I or D fares these days? 4k USD or so? If so, I think you should expect to roughly double your price to 8k if you upfare the two HND sectors to F. Ie, the round-trip upfare will be in the ballpark of 4k USD on a base 4k D or I fare ticket.