Previous thread: "Questions About Complimentary Premier Upgrades (CPU) on UA" Thread [ARCHIVE]
Guide to CPUs

CPU eligible flights -- to see what is and is not eligible see Upgrade regions

In order for you to receive a CPU, four conditions have to be met at the same moment in time:

(NB: The following does not apply to GS members, whose CPUs process at least somewhat differently, out of the PN bucket.)

1. The flight must be within the relevant CPU window:

• GS: 120 hours
• 1K: 96 hours
• Plat: 72 hours
• Gold: 48 hours
• Silver: 24 hours

If the flight is scheduled to depart after midnight central time, all of these windows open 24 hours early, due to a system glitch.

2. There must be CPU availability. CPUs for non-GS members draw from an invisible bucket that is often (but not always) pegged to roughly one or two less than the R PZ bucket. At the gate, all remaining seats are released.

3. You must be high enough on the relevant upgrade list.
There are two separate upgrade lists, used during the two different upgrade processes described in (4) below. Understand how these lists work is one of the things people struggle with the most.

The Pre-Gate List (a/k/a the "sweeps list" or "EUA list")
This list is used in the pre-gate process described in (4) below. Your presence on the list is indicated by the CPU Requested icon/language on your reservation, but you cannot find out what position you are on this list through any public method. The list is sorted in this manner:- Displaced first-class passengers (Bought two-segment F ticket, F wasn't available on this segment at time of purchase)

- GS using any method (note GS clear out of PN)

- Uncleared instant upgrades, sorted by fare class* and status (Only 1K Y/B/M, clears out of PN)

- Waitlisted instrument/mile upgrades, sorted by status of highest elite on the PNR, fare class, and then time of request (e.g.: 1K in N upgrading using miles, Plat in S using RPU applied on Tuesday, Plat in S using RPU applied later on Friday)**, after check-in, time of checking is used vs time of request

- CPUs, sorted by status of highest elite on the PNR, fare class, and time of purchase (e.g.: 1K in E, 1K in N, Plat in E, Plat in X***, Gold in G purchased in November, Gold in G purchased in December), after check-in, time of checking is used vs time of request

*The coach fare classes, in the order that is relevant to this whole discussion, are: O, A, R (for upgrades from United® Premium Plus seats to the United Polaris business class cabin) and Y, B, M, E, U, H, Q, V, W, S, T, L, K, G , YN/HN/XN/X (N is ineligible)

**Note: The upgrades above CPU can clear using R PZ space, CPU appears to be a subset, so R PZ space alone is not sufficient for CPU clearing.

***CPUs are only available for mileage tickets for certain credit card holders. It's a complicated issue that is generally beyond the scope of this thread. There is a separate thread for it.
Note the simple fare class, status and time has been replaced

The Gate List (a/k/a the "visible list")

This list controls upgrades at the gate. It is semi-visible to the public on the status page for a flight, but the status page only shows checked in passengers. Even if you appear first on the list, you might actually be fifteenth by the time everyone checks in.

This list is in the same order as the list above, except that the time-related tiebreakers (such as time of purchase) are replaced with the sequence number (which is related to the time of check-in). Additionally, certain non-revs (airline employees and family traveling for free or at low cost) are put on the gate list, at the end.

4. One of the two upgrade processes must run.

The Pre-Gate Process (a/k/a the "sweeps" or "EUA")
This process runs at certain times in the days leading up to the flight. It typically runs at 24-hour intervals leading up to T-24, at which point it begins to run more often. It is unclear exactly how often it runs, or when it stops running. There are reports of upgrades that seem to have been given by the pre-gate system even once boarding has begun.

The Gate Process
This process is manually accomplished by the GA, typically once if there are empty seats after check-in has closed, and again if there are no-shows in F. In the latter case, the GA may come onto the plane to give the new boarding pass to the passenger.

Sometimes the GA might not run the process, which makes them a Very Bad GA. On very rare occasions, they might fiddle with the process to upgrade their friends, which we call "shenanigans." That makes them a Mega Bad And Very In Trouble GA. Both of these situations should be reported in the relevant FT thread and directly to UA.

CPU FAQ

I'm number one on the upgrade list on the flight status page. Does that mean I'm first in line for the upgrade?
No, unless the check-in window has passed and the flight is under gate control.

There are seats available in F, why have I not been upgraded yet?
That's not how it works. See above.

There is R PZ availability, why haven't I been upgraded yet?
That's not how it works. See above.

Will the time that I check in affect my ability to get an upgrade?
Probably not. It is the third tie-breaker on the gate list only. See above.

Do I need to check in to get an upgrade?
No. Except at the gate. But if you're not checked in by that time, you have bigger problems.

Who are all these people on both the standby list and the upgrade list(s)?
Non-revs. See above.

But the website says that the Silver window opens the day of departure, not at T-24!
Ignore that.

But the website says that there is a "transfer" of the lists at T-24!
Ignore that.

But the agent said ____________________________!
Ignore them.

Will CPU for a UA operated flight not on UA ticket stock or listed as a partner codeshare?
Yes, if your MP account is attached

DidItClear
If the DidItClear website is going to be effective, it needs more members and trip upgrade data!

Please visit https://www.diditclear.com/ and include your trip experience with CPU's, RPU's, GPU's and any other means of upgrading available on United.

The better the data, the better the search results and experiential history.

Related threads
Understanding the United Upgrade List Comprehensively

Comprehensive Companion CPU Questions

To split or not to split PNR