About 35,000 feet (10,670 meters) over the Mojave Desert, northwest of Los Angeles, Boom Supersonic's XB-1 became the first privately funded airplane to break the sound barrier during a test flight on Tuesday.

Colorado-based Boom Supersonic plans to build the Overture airliner, which it says will carry as many as 80 passengers while moving at about twice the speed of today’s subsonic airliners.

The countdown has begun for the XB-1’s “historic” first supersonic test flight that should break the sound barrier, according to Boom Supersonic.