NASA's X-59 reaches key speed and altitude milestones ahead of community tests

NASA's X-59 quiet supersonic research aircraft completed a critical test flight, reaching Mach 1.4 (about 924 mph) at an altitude of 55,000 feet (about 16.8 km) on June 12, 2026. This marks the first time the prototype achieved these target performance levels, which are essential for future tests over U.S. residential areas. The aircraft is designed to produce a soft thump instead of a loud sonic boom, and during current tests it flies alongside another research plane that creates a sonic boom to mask its own noise.