JOURFIXE

26 января 1911 г. Совершает полет первый гидроплан, пилотируемый Гленом Кёртисом.

похоже, это первый полёт в Америке, но не в мире.
http://en.wikipedia.org/wiki/Seaplane:
The first autonomous flight by a seaplane was done by the French engineer Henri Fabre in March 1910. Its name was Le Canard ('the duck'), and took off from the water and flew 1'650 feet on its first flight on March 28, 1910.
In the United States, early development was carried out at Hammondsport, New York by Glenn Curtiss who had beaten Alexander Graham Bell and others in the Aerial Experiment Association. The first American seaplane flight occurred on January 26, 1911.