What was once a pipe dream – to fly as they did on the Concorde – American Airlines is bringing back supersonic travel.

The US airline has agreed to purchase 20 supersonic Overture planes from Boom Supersonic.

The deal is the second firm order in the last two years for Boom, which is still years from building its first commercial airplane. 

“Passengers want flights that are faster, more convenient, more sustainable and that’s what Overture delivers,” Boom CEO Blake Scholl told CNBC.

“Flight times can be as little as half as what we have today, and that works great in networks like American where we can fly Miami to London in less than five hours.”

Last year United Airlines made a commitment to buy 15 Overture jets.

Boom says the Overture jet will dramatically cutting trans-Atlantic and trans-Pacific flight times. 

“Supersonic travel will be an important part of our ability to deliver for our customers,” American’s chief financial officer, Derek Kerr, said in a statement announcing the order.

American has the option to purchase another 40 Overtures in the future.