The issue is that upgrades are based on availability. Paying customers obvbiously get first dubs. Then customers paying at full Y.

Upgrades are then allocated based on elite level and fare basis. So a Platinum on an H fare is first in the queue, then K, N, B, etc. And so on down the line through Gold & Silver.

The computer will allocate the upgrade and notify you via email (an option you can select in your OnePass account page on the website).

Then, this being FC, some passengers end up not showing up (most of these tickets are refundable) and CO fills these seats starting with 2 hours to go, based on the order in which passengers check in. That's why elites are very keen to use the On Line Check In process, which gets them in this queue as early as 24 hrs to go to their flight time.

I've noticed that you are based in Seattle. You're essentially going to be flying either to (or through) IAH or EWR. While the equipment CO operates will change over time, they are currently operating mostly 737's, which is the bulk of their fleet, and two 757-300's (these operate to IAH).

There are a number of different versions of the 737, with FC cabins ranging from 8 seats to 18 seats. Most of the 737's currently operating out of SEA have 12-14 FC seats, with a few 18-FC seat configurations.

The 757-300 has 24 FC seats.

Although not a hard and fast rule, generally you'll find that it is harder to upgrade on the flight which have the smaller FC cabins, simply because the seat inventory isn't there.

While there are a number of SkyTeam Alliance carriers that serve Seatlle, you will only have this same kind of access to FC upgrades on NW. My experience has been these are much easier to access. The only down side of flying NW is thart, if you're flying on an inexpensive ticket, you will only receive 50% of your miles toward your elite qualification (or EQM).

You can use miles to upgrade on CO but the airline does not have any revenue upgrades.

Good luck!