Hamilton Watch Khaki Aviation X-Wind Day Date H77785733. It was a Hamilton watch used on the first US postal service flight between Washington and New York, so aviation is nothing new to the brand whose prestigious aviation heritage dates back to 1919 and has included the rank of official supplier to the US Armed Forces since 1914. Geared toward the skyward bound, working with leading air squadrons and world famous pilots, Hamiltons Khaki Aviation line is renowned for providing classic aviator styling and functions specific to pilots needs.