> Once upon a time, there was a plane that could fly twice the speed of sound, 1,354 mph. > But that plane, the Concorde, has been decommissioned for nearly two decades. Since then, no aircraft builder has built a supersonic jet to take its place. > But a new plane called Boom Overture — which can fly even faster: Mach 2.2, or 1,688 mph — is moving through phases of development and a test version known as Baby Boom XB-1 will soon take its debut flight.