Today a civil test airliner, Boom Technology’s XB-1, broke the sound barrier for the first time in two decades.

Boom’s XB-1 jet breaks sound barrier on first supersonic flight - Boom’s inaugural XB-1 supersonic test flight reached speeds of more than 850 miles per hour

Previously, the XB-1's top speed was Mach 0.95, or 728 miles per hour, which it reached during its last test flight on January 10.