taking booster seat on plane

I will be travelling with my 4 year old to the states at xmas, can i take his car booster seat on the plane, as he is a little small for hsi age, plus we will need it when travelling inthe states??

If it can't be used on the plane, (that'll be up to the airline/safety rules & regs.) then it can be taken in the hold and not be counted as checked luggage.

And be checked at the jetway as well as being returned to the jetway on arrivial.

I would take it for your traveling in the States but I'd check it for the plane so you won't have to deal with it.  My 3 and 4 year olds have done fine on plane rides without car/booster seats.