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

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.

The second series of supersonic flight tests are scheduled for 1:30 p.m. Monday as part of Boom “scaling up the technology on XB-1 for the Overture supersonic airliner,” said Blake Scboll, Boom’s co-founder and chief executive.