The Lockheed Martin built experimental jet hit Mach 1.1 over Edwards Air Force Base on June 5, 2026, but a chase plane's own sonic boom masked the X 59's noise, leaving the program's central claim still to be tested.
Pilot Jim "Clue" Less pushed NASA's X-59 Quesst past the speed of sound on June 5, 2026, according to a Live Science report on the flight. It was the first time an aircraft built specifically to break the sound barrier without producing a sonic boom has done so. The flight, run out of Edwards Air Force Base in California, took the Lockheed Martin-built demonstrator to roughly Mach 1.1, or about 1.1 times the speed of sound at altitude. Within a week, follow-up runs had reached Mach 1.4, Live Science reported. By any ordinary measure, it was a milestone for the eight-year, $247.5 million program.
The less ordinary measure, the one the program was actually designed to retire, is the part that has yet to be recorded. As the X-59 went supersonic, an F-15 chase plane was trailing it, and the F-15 produced its own loud sonic boom. That boom cloaked whatever noise the X-59 was making, Live Science reported. The airframe proved it can fly faster than sound. It did not yet prove it can do so quietly, which is the property the whole program exists to demonstrate.
The "Quesst" name, short for Quiet SuperSonic Technology, telegraphs the wager: that a different shape, paired with a different rule, can let civil aircraft fly supersonic over land again. Concorde, retired in 2003, and the Soviet Tu-144 were barred from supersonic flight over populated areas for the same reason, that the pressure wave a slender supersonic airframe produces on the ground reads as a thunderclap. NASA and Lockheed's bet is that a long, narrow fuselage, a top-mounted inlet that keeps shockwaves from coalescing, and a flush cockpit with no forward window for the pilot can keep the on-ground thump to roughly 75 EPNdB, a unit that measures perceived noise. Concorde's boom measured roughly 105 to 110 EPNdB, and the program compares the X-59's target thump to the sound of a car door closing in the next lane.
The X-59's airframe is built around that goal. It is 99.7 feet long with a 29.5-foot wingspan and a maximum takeoff weight of 32,300 pounds. A single General Electric F414 engine, the same family that powers the F/A-18E/F Super Hornet, produces 22,000 pounds of thrust with afterburner. The cruise target is Mach 1.42, or about 937 miles per hour, at 55,000 feet, with a maximum speed of Mach 1.5. Because the cockpit is sealed to keep the nose aerodynamically clean, the pilot sees through a 4K forward camera paired with a Collins EVS-3600 multispectral imager, what the program calls the External Vision System.
The program timeline is long enough that the June 5 supersonic pass reads as a step rather than an answer. NASA awarded Lockheed Martin the $247.5 million Low-Boom Flight Demonstrator contract on April 2, 2018; the U.S. Air Force designated the aircraft the X-59 on June 26, 2018. First flight came on October 28, 2025, a subsonic run from Air Force Plant 42 to Edwards at about 230 miles per hour and 12,000 feet. A higher-altitude cruise-profile flight on April 3, 2026 reached 20,000 feet and roughly 460 miles per hour, the platform's last step before the supersonic envelope opened. Each milestone has a job: prove the airframe, prove the systems, then prove the noise.
That last job is the one the program is structured around. Between 2025 and 2027, NASA plans community-response overflights, which are acoustic surveys of people on the ground hearing the X-59 pass overhead, in carefully selected U.S. cities. The data are slated for ICAO's Committee on Aviation Environmental Protection and the FAA in 2027, with the goal of informing a potential rule change on commercial supersonic flight over land in 2028. The airworthiness case, the regulator engagement, and the public-acceptance work still have years to run.
What changed on June 5 is narrower, and worth saying clearly: an aircraft designed to retire the overland supersonic ban now exists, and it can fly. The harder public-interest work, proving the noise profile is acceptable to people on the ground and writing a rule around it, is still ahead.