I'm hoping this post will help out those who are flying with their Corgis in-cabin since I really didn't know what to expect. However, please note that my experience and circumstances may differ than others.
My now fiancé (I just got engaged!) and I recently traveled from Maryland to Maine and back with our puppy, Casey. He was 18 weeks old weighing in at about 16lbs. We flew non-stop on US Airways, and their pet policy is that they accept one small dog, cat or bird per cabin for $125 each way, they must remain in their approved carrier/container under the seat directly in front of you, and there is no weight restriction. They have different maximum dimensions for a hard-sided carrier vs a soft-sided carrier, and I chose to fly Casey in a soft-sided one (which must be 17in long x 16in wide x 10in tall and have ample room for the animal to stand up and turn around). Also, the carrier is also considered a carry-on so I packed a larger suitcase to be checked instead of my usual carry-on sized one, but that worked out for the better since I needed room to pack his food and toys.
I researched and read reviews on so many different carriers that it made my head spin! I wanted it to be sturdy, but I wasn't willing to pay too much since Casey would be too big to ever fly in-cabin again after the trip. Ultimately, I just took him to PetSmart and let him try some out and he seemed to really like the Sherpa brand carrier. I purchased the medium sized one online since it was much cheaper, even though it was 1 inch longer than the allowed length. I figured if the airline had an issue with it, I could argue that it could be smushed to 17 inches. After receiving it, I quickly realized it was somewhat of a tight fit since he couldn't stand up, and even though he was able to turn around and curl up in it, he seemed just the slightest bit cramped. I spent about 2 weeks training him to go inside and getting him used to being zipped up and carried around, and he was fine with it. I was still a little uncomfortable with the size of the carrier, so I ended up exchanging it for the large size, which is about an inch larger in dimension all around than the medium. I felt pretty brazen considering I didn't know if the agents at the ticket counter would whip out a tape measurer or not, but I took a chance and went with it.
On the day of the flight, I was a nervous wreck! We went up to the ticket counter and after checking in, we told them we were flying with a pet. The guy behind the counter merely glanced over to Casey in his carrier, and said, "Ok that'll be $125". No measuring at all and I was so relieved! They gave him a boarding pass, and he was good to go! Before going through security, we took him to the pet relief area (Reagan National has a nice grassy area outside) where he did his business. We then carried him over to security, where you have to take your pet out of the carrier to be scanned. I had initially put a leash on him, but was told that the clasp could set off the detector, so I had to take it off. I carried him through the metal detector (no body scanning) with his harness and collar with tags on, and it didn't go off. They did have to swab my hands, so I just knelt down to hold him by his harness while they swabbed my hand one at a time. The TSA agents absolutely LOVED him and all wanted to pet him, which he loved since he's our little social butterfly, and it also gave us a chance to put our shoes back on and gather our things. One of the agents informed us that they were a pet friendly airport and that Casey didn't have to go back into the carrier until we boarded our plane, so he sat with us in the terminal while getting lots of attention from other passengers.
We put him back in the carrier before we boarded, and while walking to our seats, one of the flight attendants spotted him and said, "I know who my favorite passenger will be today!". lol! We were flying in a smaller aircraft (2 seats, an aisle, and 2 seats), and the carrier didn't fit completely under the seat, but none of the flight attendants said anything about it. It's also a good thing that I'm short or it would've taken up more leg room. Casey did great! He either laid down or napped the entire time, because he didn't let out a peep.
It was pretty much the same experience on the way back as well, except I wasn't sure Portland International Jetport in Maine was considered pet friendly, so he stayed in his carrier while we waited at the terminal.
Here he is in the car on the way to the airport. He loved poking his head out!
All in all it was an awesome trip for the 3 of us! I just wish he was smaller so I could fly with him more often. ;)