I’ve been reading about the return tour of an American cult rock band from the 1990s, Neutral Milk Hotel. The reviews all mention the album that’s considered their best, “In the Aeroplane Over the Sea.”
Aeroplane was first used for a “heavier-than-air aircraft,” according to the Oxford English Dictionary, in 1868, that is, before the aeroplane before it was invented. The OED describes airplane as “chiefly North American”; its first citation is from a 1906 Scientific American article that notes: “Air-plane is a much better word than aeroplane. It is as good etymologically, and much better when it is spoken.” The OED comments: “Airplane became the standard U.S. term (replacing aeroplane) after it was adopted by the National Advisory Committee for Aeronautics in 1916. Although A. Lloyd Jones recommended its adoption by the BBC in 1928, it has until recently been no more than an occasional form in British English.”
Google Ngram Viewer confirms this analysis:
Of course, I’d bet that in both lingos, the far preferred term is plane.