Where did you get this idea of flying? I wondered if I had a misconception there but any source I could quickly find on the web disagrees with the "can move with six degrees of freedom" definition and uses a definition like "doesn't touch ground or sea while moving through the air" instead. (Wikipedia on "Flight" / "Ekranoplan" / "Ground-effect vehicle", Merriam Webster on the word "Flight", and search for "what is flight" if that's not enough).