I bought my daughter a seat for the flight to/from our next cruise. I would like her to sit in her carseat during the flight, but am concerned about this wide carseat fitting in a coach class seat. The base of the seat is 13" but the actual with of the seat part is 20"

Does anyone have any experience with this particular seat in a regular coach class airplane?

It will be just the two of us on the flight, so I won't mind lifting the armrest and being a little squished, but I'm not so sure about my potential neighbor.

Days until my next cruise:

Renaissance R1, July 2000: Greece and Turkey
Radiance of the Seas, July 2002: Alaska
Golden Princess, November 2003: Eastern Caribbean
Grandeur of the Seas, November, 2004: Western Caribbean