The 93-year-old Curtiss MF Flying Boat sold for $504,000 Tuesday afternoon, an auction spokesman said.
The buyer bid by telephone, competing against two other phone bidders and one in the room.
The "flying boat" designed by the aviation pioneer Glenn H. Curtiss. In the cockpit, barely wide enough for two people, are a pair of steering wheels, along with wooden pedals that control the rudder. The pilot could hand-crank the engine, though bringing it to life would require an about-face and a stretch - the engine is above and behind the cockpit.