buy a few small toys/small board books from the dollar store and stash them until you're on the plane. She can sit on your lap and check out her new toys without getting too bored. small juice boxes, wipes, non-sticky snacks - should be good to go. And definitely check the car seat. Some airlines have big plastic bags to put them in, but you can bring one of your own (clear) plastic bags to keep it from getting dusty or dirty in the luggage area.