Just a little info for you..... They always make me take DD out of a sling/carrier to put the infant seatbelt on. They sometimes make me take the carrier off too, even if it's a HAB.
What - when they are taking off and landing only I hope? God I don't know what I'll do if they make me take her out if I'm trying to get her to go to sleep. She doesn't ever let me rock her to sleep - hasn't for a long time. I don't have a HAB, I'll just have my KS mei tai, my Beco will be packed in a suitcase.