We're traveling in J from LHR-JFK but with the baby as a lap child not a separate seat. I believe the plane is a 747 or a 777. Ideally, I'd like to bring the car seat on board and stow it in an overhead bin or somewhere else.

The dimensions are probably 17 x 24 x 22 inches.

Is this likely to be possible? It would avoid damaging the car seat if it is sent as checked luggage.