As a giant motherfucker the absolute lack of space and general claustraphobia of trying to fucking move about on the plane. I've started always flying first class now because goddamn I need that extra room, especially when flying with the missus since she's a lanklet as well.
Also not technically on a plane, but airport security in general and the TSA especially get right on my fucking nerves. It's a gigantic, pointless waste of time and money, that doesn't do anything other than make the entire experience worse, and cost a fortune, and it'll never ever go away because it's basically just another BS federal welfare employment-for-retards scheme at this point.