I'm a former Flight Attendant who now flies a lot with my own three kids. I can totally support everything Little Angel Fire said!!! Great answer!

I only have to add some practical tips, since I fly between Europe and California about twice a year and only once didn't have the seat with me.

My youngest just completed her 6th round trip transatlantic and at 3 1/2, I brought along her car seat. Magic for getting her to sleep! She is a very active child and she was much more comfortable and settled in her familiar car seat. On our arrival, the airlines lost three of our four bags (they were returned two days later). If I had checked our seat, who knows if it would have been there but this time I had no worries about our 2 hour ride home. I had the car seat with me, strapped it in my husband's car and away we went safely!

If you're curious (especially since she's past 40lbs.) she sits in a Radian 65. I picked it because it's FAA approved and harnesses to 65lbs. The Radian 80 is even better...

Two year olds are too small for the lap belt and boosters, which should only be used after the 4th birthday, are never FAA approved. It has to be a hard-backed seat with an internal harness.

First check that your seat is FAA approved IF you are flying a U.S. airline (check with your non-American airline if not). Most car seats sold in the U.S. are approved.

http://www.faa.gov/passengers/fly_childr...

I will admit that I've strapped down an unhappy little one more than once. Toddlers hate to be confined and simply don't understand that they have to be seated sometimes. Firmly anchored in, I could then consol them while we landed.

Not to scare you but there was recently a case where a family was off loaded because they couldn't keep their toddler strapped into the seat during take-off when it's required.

To get the seat through the airport, all sorts of gizmos are sold like this;

http://www.gogobabyz.com/products/gogo_k...

Some parents manage to bungee cord their seat to their stroller or make it fit inside. They also have backpacks for car seats, which would mean having your hands free.

I simply use a small metal luggage cart with an extra bungee cord and it works great. I skip on the stroller and she can even ride in it (and she's 3 1/2). She usually prefers to walk and then I can put the carry-on bag(s) on it. It didn't cost me a thing since I already had the luggage cart and the bungee cord!

I'm taking a car seat while flying long-haul alone with three kids so it can be done! Do what works for you and practice at home before heading to the airport.

For the record, I have to point out that some foreign airlines wont allow car seats so they're not universally accepted. One low-cost Irish company bans them completely but in the U.S., it's your *right* to use an FAA approved seat if the child has a booked place.

By the way, car seats do NOT have to go by the window. This is true on some aircraft but if there are two aisles, you can put it in the center. Especially important if you are seated in the "bulkhead" seats. It can't block another passenger's access to the aisle, that's all.

For more information on flying with children from someone who has both done it and worked in the industry, I wrote an article a few years ago. I put it on a blog to share with other parents. Feel free to visit;

http://flyingwithchildren.blogspot.com