During the second supersonic flight of the XB-1 technology demonstrator today, the jet exceeded Mach 1 three times without a boom being detected by microphones on the desert floor below.

If you've been keeping tabs on aviation news as of late, you saw that Boom Supersonic just recently broke the sound barrier with its XB-1 demonstrator aircraft. Oddly enough, no one on the ground heard a thing during its "boomless" cruise.

When the experimental XB-1 aircraft achieved supersonic speeds on a test flight, it did not create a disruptive sonic boom – thanks to a physics phenomenon called the Mach cutoff

Hot on the heels of its milestone supersonic flight with its demonstrator aircraft, XB-1, Boom Supersonic has another surprise up its sleeve. During the demonstration flight on January 28, 2025, the XB-1 broke the sound barrier three times,

Boomless Cruise is based on physics known as the Mach cutoff, in which a sonic boom refracts in the atmosphere and never reaches the ground. This was achieved by breaking the sound barrier at a higher altitude, with the exact speeds varying based on the atmospheric conditions.

Boom Supersonic passed a major milestone last month when its XB-1 prototype became the first civil aircraft to break the sound barrier over the continental US. Less than a month later, Chief Test Pilot Tristan “Geppetto” Brandenburg has once again surpassed Mach 1 in the experimental plane while flying as high as 36,