United Airlines has teamed up with Denver-based start-up Boom Technology to transport passengers at supersonic speed before the end of this decade. The Chicago-based airline has become the first to sign an aircraft purchase agreement with Boom. It plans to buy 15 of its supersonic Overture airliners, with an option to purchase 35 more once they meet its safety, operating and sustainability requirements. <em>The National</em> looks at the future of supersonic travel: <strong>What does it mean to travel at supersonic speed?</strong> It's travelling at a pace that surpasses the speed of the sound. Traditionally, supersonic flight has been an experience reserved for military pilots, air racers and astronauts. In 2017, Boom partnered with Japan Airlines to develop Overture, the world’s fastest and most sustainable airliner. Investing $10 million with the option to purchase up to 20 Overture aircraft, Japan Airlines has supported the venture by sharing expertise and perspective on operations and inflight experience. Supersonic travel will offer many benefits. Besides reducing post-flight fatigue, it will make it more convenient to travel more often. “A reduction in travel time would help travellers get to their destinations faster and, equally important, return home more quickly,” said Yusuke Yabumoto, Japan Airlines director of the Silicon Valley Investment and Innovation Group. World hubs like Tokyo could be reached from Seattle in six hours instead of 10. A flight between London and New York could take 3.5 hours instead of 6.5, whereas the journey from New York to Frankfurt would be reduced to only four hours. Today, it is only an artist’s drawing – even the prototype has not flown yet. But that could soon change. Overture will be the fastest and most sustainable supersonic airliner, <a href="https://boomsupersonic.com/overture">Boom</a> claimed on its website. “Overture travels at twice the speed of today’s fastest passenger jets, leaving no destination out of reach," it said. It is guided by three core principles – speed, safety and sustainability, the company added. Boom intends to roll out the first prototype of Overture by 2025 and hold its maiden flight the next year. United is aiming to use it in its fleet by 2029. Boom is inspired by the technology of the supersonic Concorde, which British Airways and Air France began using in 1976 across the Atlantic. But the company’s founder and chief executive Blake Scholl said that certain elements of supersonic travel would need to be “fundamentally different” from Concorde’s for the concept to thrive. “Concorde was a technological marvel of its time, but economically and environmentally unsustainable,” said Mr Scholl. “It was too expensive to turn a profit and reach economies of scale … its noise pollution made it unwelcome at most airports,” he added. Concorde retired in 2003, three years after an Air France flight crashed into a hotel, killing everyone on board. At speeds twice as fast as today’s passenger jets, United’s new Overture fleet will open countless possibilities for new experiences and human connection. “Our mission has always been about connecting people and now, working with Boom, we will be able to do that on an even greater scale,” Scott Kirby, United’s chief executive, said. “Boom’s vision for the future of commercial aviation, combined with the industry’s most robust route network in the world, will give business and leisure travellers access to a stellar flight experience,” he added.