We are taking my son on an airplane ride and I was curious if he should sit in his carseat during the flight? I was planning on doing this because of possible turbulence, hoping he would nap, and also he knows his carseat and that he has to sit there. Everyone I've talked to thinks I'm nuts for bringing his car seat and some even think it's not allowed. So I'm curious what you all have done or would do. Thanks!
#2 BFP 8/23/14, EDD 5/1/15, M/C 9/17/14 - Forever in our hearts

Re: Car seat on airplane?
If you buy a plane ticket for your kid, they are legally obligated to allow you to use a [FAA approved] car seat.
There's some good blog posts linked at the bottom here: https://carseatblog.com/18895/flying-with-kids-carseats-the-checked-carseat-controversy/
DD has been on probably 25+ flights, always in her carseat. Really I see the safety thing as a bonus. For me it is just more convenient to know that I have her in a seat and don't have to try to contain her on my lap and she sleeps much better in her carseat than on me (and I have my hands free while she's napping). We've done a lot of long flights. We make sure that she's strapped in during take-off and landing, and any turbulence where they tell passengers to return to their seats and buckle up, but the rest of the time she can move around just like she were a lap child.
We bought a separate carseat just for air travel, because the ones in our cars are big and heavy. Lucie's list recommends a few smaller/lighter weight convertibles. We bought the Evenflo one. It is so much easier to carry around than a heavier seat:
https://www.lucieslist.com/best-convertible-car-seats/#FLYING
Like @annieluvsjordan suggested, we also bought one of these, which works great for getting through the airport:
https://www.amazon.com/Go-Go-Babyz-QRKIDZ-Kidz-Travelmate/dp/B000JJK9EY
Our family all lives across the country, so for us it made sense to invest in a couple things that made long flights and time in airports easier on all of us.
DS was in his car seat on the plane when we flew in November. We also had the attachment for the car seat so we could roll him through the airport. It was worth every penny. We did gate check our stroller too but that was because our luggage was being sent directly to our hotel and we needed our stroller before the luggage would get there.
Great! It folds up and will fit in the overhead or underneath the seat.