This carrier worked perfect with SouthWest extended leg seats!! It was my first time traveling with my Tito, so I decided to give us an upgrade, just in case the standard seating was too tight. For me it was the right decision as my doggy is a big 14 pounds version...he is light, but muscular, long and with a big head. LOL He definitely took advantage of the side openings. I don't believe I would have been able to open those "carrier wings" in the standard seats...it was kind of tight on the "extended leg/first class" on SouthWest. If your doggy is smaller than 10 pounds, I think you both would be ok . I read in another review this carrier did not fit on a Delta plane, but in SW was perfect. The airline was also very pet friendly! I had no issue at all!!! We flew to Puerto Rico.