All strollers and car seats are tagged with a pink "Claim At Gate" tag. They are placed in the Cargo Bin for the flight and redelivered to you at the gate at your destination.

The car seat in the aircraft can be hit or miss. The ONLY way to ensure you can bring it on is to buy a seat for it. You can always speak with the gate agent as well as the flight crew to see if there is an empty row that you can move to and put the car seat in the window of that row. However with as full as we have been those chances may be slim. Our loads have been continuously in the high 80% for the last few months. I prefer to have a small child in a car seat if possible and will do what I can if I have the availability to do so. It's much much safer for everybody that way however I can't speak for how the cabin crew you will have will respond. I'm sure that they will be willing to work with you as you can speak to them when you set the car seat down by the cabin door when you board.