I am hoping to apply UA Plus Points to upgrade some CM segments. What tool(s) exist for searching for Z inventory before calling?

I've tried united.com's advanced search but it doesn't seem to find Z inventory, even on flights I've already confirmed by calling have Z inventory.

Generally (ie not always) Z = D or D-1

They don�t publish Z, but you can call and they will tell you. I can also search it too in a roundabout way, but will your surname and PNR

My best tool has been to see if Business Saver Award inventory is shown by UA.

I ruled out relying on this when I specifically looked up a flight for which I confirmed Z space by phone, but did not show in Business Saver inventory. The only reason I didn't take the inventory when I called was, United Mexico was closed so I couldn't be transfered after 1K desk confirmed Z space. To verify my findings, at least for this one CM segment, I checked the award inventory immediately before calling back to actually take the space. Cost me 80 Plus Points for two CM segments (horrible redemption value) but better used than lost.

Not sure if I did something wrong, Using the same technique I can find Saver inventory (I Class) on other CM flights. So perhaps Z is a superset of I?

I am considering qualifying for COPA Presidential status instead of United 1K status during 2020, but I'm not sure if I understand how the upgrade certificates awarded by COPA are used on United flights. If United.com shows "Z" inventory in advanced mode, does that mean I can confirm an upgrade on that United flight using COPA regional/global upgrade certificates? If yes, that seems WAY too good to be true. United "Z" inventory is discount paid business class and is very often available. Or is the "Z" class required by COPA for applying its upgrades something different, like United's "PZ" fare class (upgrade inventory for its own PointsPlus system) or United's "ZN" (non-elite everyday award space under United's old award system)? I don't want to earn COPA status and then learn the hard way that it is all too good to be true.

To use a Copa cert:

You need Z on CM to upgrade
You need PZ on UA to upgrade

You can now upgrade pretty much any UA fare class with a Copa cert (so long as PZ exists)

Thank you for your reply.

Unfortunately, it rarely exists in advance. I guess I won't be qualifying for COPA status since the upgrades will be equally impossible to confirm in advance.

That's incorrect -- I'd call back to get some PlusPoints redeposited. It's supposed to be 1 RPU for one directional upgrades with Copa -- so 20 PP per direction. However, you cannot mix between Copa and UA (it would be 40 if you did). But since you're 1K, you should qualify for CPU on the UA metal routes anyways.

I seem to be confused reading some of the PlusPoints stuff where on CM it now seemed to be _per_ _segment_ instead of one RPU for the entire day-of-travel...

That has now changed. Just confirmed with UA Web Support, upgrade only per segment.
And it has to be done online too: https://www.united.com/web/en-us/app...de.aspx?POS=US

The ominous line about 40 PlusPoints per traveller would make this another nail in MileagePlus's coffin.
I confirmed with Copa they had Z, also checked Business Saver Award space, but UA's website says there's no space.

Another stealth devaluation, what a surprise

Si I had this same problem recently on a CM itin. UA Plus Points have become useless for attempting to upgrade on CM it is a total waste of my time to even call. The website throws an error message so we cannot know why it does not work (no Z available or just website malfunctionality). We call UA web support and they can do nothing except tell us Z is not available. Which Copa then denies! But they are correct that this is UA's issue and CM cannot know why UA's system fails to interface.

For years UA had the best upgrade systems and paths using MP instruments but the recent downgrades of benefits and even of previous regular functionality like working online upgrades is turning MP into one of the worst. It is remarkable how fast it is decaying and how bad the experience now is. En primera as always it was DL and I quite on them years ago. Then AA, now UA.

Soo I am following the new path of qualifying for CM status by crediting all Star flying to CM except long UA flights. The only reason for me to credit to UA is now for more lifetime status but I do not expect this goal will remain at the same level before I qualify (have 1MM already but I need 0.7MM more to reach 2M and those benefits are not greatly more than current levels).

I think that many people are following this plan. Because at the Clubo Copa last week, I used MP card to access and the agent said, ah you are getting millas with us (CM) and I say, Si! Es mucho mejor ahorra. I think I am not the only one who he sees doing this.