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,

Boom Supersonic’s XB-1 creates a sonic boom inaudible from the ground below when flying at the exact right speed and altitude.

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