The speed was achieved in level flight at an atitude of 10000 ft. The aircraft was flown by Eurocopter test pilot Hervé Jammayrac and Flight Test Engineer Dominique Fournier.

To see a video of the X3 in flight, follow this link.

Source: "Airbus Helicopters X3 F-ZXXX", Musée Air+Espace and Airbus Helicopters Press Release, 11 June 2013