We have a Cosco Scenera Next for travel, and are about to do our first plane trip with it. Will it fit rear facing in coach, or do I have to use it FF? (we'll be on an American Airlines MD-80, fwiw).

He meets the height requirement to FF, but not the weight limit. He is < 1 year, so he is definitely RF in the car - I'd prefer to keep him RF in the plane if possible, but have heard mixed things about it fitting that way.