CO flys with F/C full almost on every flight. They will upgrade people at the very last minute to fill F/C cabin. So a "history" would not give you an accurate picture of the "real" situation.

I would suggest looking at upcoming flights. Check the flights for the next 7 days or so and see which ones have F/C available and what the availablity of coach is. The less people in coach the better your changes of an upgrade.

Also, if you have the time, using ITN, select your flight and then check the seating. If a lot of the "prefered" seats are taken, then a lot of elites have booked and can upgrade ahead of you. But if a lot of preferred seats are available then upgrade changes are better.

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