On 10 April 1963, the "X-1" made its first hovering flight. On 20 September 1963, the first transition from hovering flight to horizontal flight took place. The "X-1" was first publicly exhibited at the May 1964 Hannover Air Show. The VJ 101C "X-1" flew a total of 40 aerodynamic flights, 24 hover flights and 14 full transitions. In the course of these tests, the sound barrier was broken for the first time by a vertical takeoff aircraft; however, on 14 September 1964, a defect in the autopilot caused the "X-1" to crash, sustaining some damage as a result. On 29 July 1964, the VJ 101 C flew at Mach 1.04 without use of an afterburner.