Originally Posted by nall

Here's how the AA upgrade process works:

First, there is "advance" upgrade inventory bucket (A for first, C for business on three-cabin/INTL) which can be reserved any time, with either:
(1) A system-wide upgrade,
(2) A business upgrade certificate,
(3) 15,000 - 25,000 miles plus a co-pay if not on a full-fare ticket. (Co-pay ranges from $75 for US domestic, $150 for Hawaii, and $350 for INTL).
(The miles and co-pay are different for going from business to first on a three-class flight, but I forget those amounts.)


As for elite upgrades, they are processed as follows:
(1) Top level elites can clear 100 hours out,
(2) Mid-tier elites 72 hours out,
(3) Low-tier elites 24 hours out.

The algorithm for determining who gets what upgrade works as follows:
(1) Sort by elite status,
(2) Sort by full-fare vs non-full fare,
(3) Sort by connecting vs non-connecting,
(4) Sort by time of upgrade request.
Example: a top-tier elite on a discount fare trumps a low-level elite on a full fare ticket, but a top-tier elite on a full-fare trumps a top-tier on a discount fare.

For top tier elites, all domestic upgrades are complimentary. For all others, upgrades require a "sticker" for every 500 miles flown (rounded up with a grace amount, so 510 miles = 1 sticker, 600 miles = 2 stickers). Stickers can be purchased, and you receive 4 free for every 10,000 miles flown.

Finally, you can designate one other passenger (booked with you or on a separate reservation) to be upgraded with you, inventory permitting. They will be with you in the queue, but your upgrade will only be processed if 2 or more upgrades are available. If only one is available, you'll be by-passed.