Start by looking at the Continental Fare Bucket List. The higher fare class you're in, the better, it's a sliding scale.

Platinum on an H fare? You're in nearly the best shape you can be.

Gold on a U fare? Depends on the route.

Silver on an L fare? You're in terrible shape. It's probably not going to happen.

The only exception to this are the "instant" full Y upgrades for elite members. A Continental elite member traveling on a full Y or B fare will be cleared before elite traveling Non–Full–Y/B fares. Also, CO Platinums on M fares can have an instant upgrade applied at the time of ticketing if AN inventory is available.

Some aircraft have more F seats than others, relative to the number of Y seats.

In descending order of preference, here is every plane in CO's fleet that currently serve routes that offer complimentary upgrades. Lower numbers are better; think of it this way, there is one F seat for every 7.33 Y seats on the 738 with mid–cabin lav. Beware, though! Planes with more F seats or those equipped with BusinessFirst seats (777, 767, 764, 752) may draw more savvy Elites looking to score an upgrade!


M: Mid–cabin lav version
** BusinessFirst seats! May attract a lot of savvy elite flyers.
~ High density 767-400 flown by CO Micronesia; often shows up on HNL-US Mainland and HNL-Asia destinations. It has also been recently spotted on various US Mainland-Europe runs (EWR-MAD comes to mind as an example).
Red planes types are currently undergoing renovations to increase the capacity of the FC cabin by 2 seats. The 738 (non mid lav) will have a total of 16F seats, the 738 (mid lav) and 739 will have 20F seats when the process is finished.

Check the fare classes up front to see how many seats are left. Seat maps will not do the trick. Do not rely on seatmaps. The KVS Tool (subscription), Expertflyer (subscription), PTT (free) and www.SeatCounter.com all provide services to look at seat bucket availability. The master class for first class seats on CO is "F" (do not confuse this with "J" the master class for seats sold as BusinessFirst). The subset of "F" that keeps track of seats available for EUA upgrades is "R". For battlefield upgrades, "R" seats are not entirely relevant, open first class seats are given out in the order set out in the Battlefield Upgrade post when the gate opens one hour before departure.

Continental does not "publish" R availability, however, and there are currently no publicly available tools that can query this bucket. Querying the R bucket therefore requires a bit of legwork. The most effective method currently available is to use continental.com and attempt to book a flight using the Advanced Search page. On that page at the very bottom there is a checkbox for OnePass Reward Upgrade. If you check that box it will query the R bucket. If the inventory is available your search results will include flights that have the price + miles listed and it will indicate that the upgrade is available. If no R inventory is available the results will indicate that no upgrade seats are there. This is slow and somewhat painful, but it seems to be the only option available to the public right now. To determine how many seats are in the R bucket you should repeat the search, increasing the number of passengers in the reservation until the results no longer indicate that the upgrade is available. Also note that if you are a non-Elite you must specify the fare bucket that you want to search, as the least expensive buckets are closed to upgrades for non-Elites. The easiest solution is to specify a M fare in the search, as just about every route has such a fare and it should have availability in most cases.

The dreaded upgrade flirt, more bark than bite if you ask me.

...Try at your own risk!

CO often sells all the seats up front on transcons in advance, leaving little for EUA, let alone battlefield. Sometimes transcon F is sold out a week or two in advance!