Since the last commercial supersonic flight 11 years ago, the world has accelerated in every respect but one: Instead of increasing speed, airlines have focused on driving down costs by commissioning ever-bigger planes crammed with ever more people. In 2003, for example, a Boeing 747-400 configured for three classes could carry 416 passengers; today’s Airbus A380 can accommodate 525.
Yet the dream of flying faster than the speed of sound has never died.
Mach 5, Anyone? Supersonic Flight Is Again Poised for Takeoff – Bloomberg.