There are dozens of discussions about airlines and carry-on bags here on EpicSki, so I'll apologize in advance for starting yet another. In my defense however, most of the threads I saw were fairly dated and none addressed this specific issue.
As is the case for most of us, I'd prefer to bring my boots and other essential gear with me in the cabin as carry-on luggage so that if (when?) my checked bags don't arrive at my destination with me, all I need to do is rent some skis. For this trip, the odds are relatively high that my checked luggage won't get there when I do. In fact, with a change of planes in Denver with only 40 minutes between arrival and the departure of the second leg to Calgary, I think I'll be lucky to make the flight, let alone my bags.
This is the first time for me on United, at least for leisure travel, and I'm concerned about the many carry-on issues that United passengers have documented recently. United's carry-on policy is similar to that of most airlines - 45 total linear inches with max bag dimensions of 22" x 14" x 9". What sets United apart however is the apparent hyper-aggressive enforcement of all of the dimensional limits, specifically the 9" restriction. The on-line forums have many stories of passengers having their carry-ons measured in the metal bag cages we've all seen in airports by United gate agents The measuring devices are actually 23" x 15" x 10" but what apparently makes things difficult is meeting the "glide" standard that United seems to be applying. This means your carry-on must be able to fit in the cage without touching any of the sides - if you have to assist it (i. e., squash it down, push on it, etc) to go in or out, United makes you check the bag.
I have two alternatives for carry-ons, but both are likely not to meet the "glide" standard United seems to be applying. My boot bag is smaller than most, but still measures 16-1/2" x 14-1/2" x 12" with any clothes stuffed in the bag. The 12" side has a small zippered pocket and can easily be squashed down to 9" if I leave the pocket empty. That means assisting the bag in/out of the measuring cage - thus failing to meet the "glide" standard. My other alternative is small rolling backpack, nominally 22x14x9, but actually measuring close to 23" on the long side. The protrusion on that side is a piece of thin, flat plastic that is the back border of the bag. It can easily be pushed down to clear the cage but again would fail the glide standard.
So, I'm soliciting suggestions. I really don't want to have to spend money on new "Cabin-OK" luggage (21-1/2x13-1/2x7-1/2) but also really want to make sure I have my boots, ski pants, UA, socks, goggles, helmet and the like with me when I get to Banff. I'm sure everyone has seen passengers struggle to shoehorn obviously oversize carry-ons into the overhead bin, a la the "Seinfield" episode with Elaine on the commuter flight, but that's not really what we're talking about here.
Finally, does anyone have recent experience with United and their apparently overzealous enforcement of carry-on policies?