Why are you "On a train" yet "In a car" when you are inside both vehicles? "On a bike" makes sense but "On a plane" seems wrong as you are actually inside the plane rather than on it. Answer Generally speaking, the metaphoric senses of get on and get in follow dimensionality: the object of on is a Surface , i.e, an object with 2 dimensions, or the surface of a 3-D object the object of in is a Container , i.e, a bounded 2-D or 3-D object In terms of conveyances, humans get on a raft, a horse, a bicycle, a sled, a wagon, a skateboard, a surfboard humans get in a car, a boat, a ship, a railroad car, a trolley, a bus, an airplane This much is predictable. The problem arises with scheduled public conveyances; in that case only, a human who gets in the conveyance physically also is on the roster of passengers metaphorically ( on the roster is a 2-D "page/paper" metaphor). So one can be said to get on the bus, the plane, the train, ...