FAA Moves to Allow Civil Supersonic Flights Over Land, If They're Quiet Enough

The FAA moves toward allowing civil supersonic flights over land using a new noise-based rule, outlined in a notice of proposed rulemaking published Thursday. The plan would replace a 1973 ban on non-military supersonic flight over the U.S. The FAA says operators could cross the sound barrier if sonic boom overpressure at the surface does not exceed 0.11 pounds per square foot (psf) and if they demonstrate compliance in test flights. The threshold is described as below 0.6% of the boom generated by Concorde in NASA’s explanation. Concorde flights historically kept supersonic speeds over the ocean. The FAA proposes two compliance approaches: “Mach cutoff” profiles that prevent booms from reaching the ground and “low-boom” aircraft designs to reduce shock waves. Boom Supersonic’s XB-1 achieved a Mach 1.12 level-flight “boomless cruise” in February, while NASA’s Quesst program supports low-boom testing for the Lockheed Martin-built X-59.