We had the same issue when we were flying last year, we didnt know which car seat to get because the two we had didnt have a single thing written on them about FAA guidelines. I did a lot of research online and found that most car seats are approved. I got the manual out to the car seat we were going to take with us and read carefully through it and found where it talks about using it on a plane.
This is the car seat we used, if you click on the product support page, there is a manual download. On page 44 & 45 it takes about securing the seat on FAA aircraft.
http://evenflo.com/Products/Evenflo/...ibute_LX/#Ella

Also you can type into Amazon search - FAA car seat and a bunch will come up.

Hope this helps.