Booster seat on an airplane...do we have to check it?

[my2sweets]

We just got back from vacation-flying- and took both girls seats. Dd1 had a low back booster(just raises her so the cars belt fits correctly. Dd2 uses a harness(that can turn into a high back booster later). We gate checked both of them. We try really hard to never check any bags. This was their first flight they didnt sit in their carseats on the plane and the lady at the gate just had me put the seats in bags and she put a tag on them. We carried it down to the plane door when our row was called, left it, boarded, and when we landed the seats were right outside the plane door waiting on us.