This is a Significant Other milestone.
The date the American Helicopter Society (then known as The American Helicopter Society, Incorporated and now known as the Vertical Flight Society) was formally recognized in the state of Connecticut. The initial, formative meeting of the society had taken place earlier that February.
Ralph Alex was the first President of the society.
Souce: "History", AHS Staff, AHS web page, last accessed Jan 02, 2018