Successful demonstration of the 1922 Berliner No. 4 machine
Friday, June 16, 1922
- College Park Airport, Maryland, United States of America 
This is a Momentous Operational milestone.
Description:
This is deemed to be the first successful demonstration of a controllable helicopter in the USA, capable of hover, transition into forward flight and landing safely.
Source: The Berliner Vertical Lift Aircraft 1919-1924, J. Gordon Leishman, VERTIFLITE Spring 2002, Page 31
