Actually when I flew United from Korea with Tinkerbell I had her in her pink kennel, but they said it was not the right size but they still let me on the plane with it. We flew almost 10 hours and no problem, once I got to San Francisco, same airline made a big fuss about my kennel(the same one I had just used for a 10 hours trip). They actually made me buy a sherpa bag(they were really nice and I got it for $30.00 dollars thru them) They even gave me a united airlines blanket for Tinkerbell

The bag was really huge for Tinkerbell but she plenty of room to rest. Our next flight was a 2 hour flight to Boise, Idaho.
P/S I didn't know they sold them there

Or maybe we just got lucky
I was afraid we were going to loose our flight and after 10 hours on a plane with 3 kids and one Yorkie, that is the last thing I wanted