NASA reported on September 4 that its X-59 completed flight 25 on August 21 from Armstrong Flight Research Center in California. The 72-minute sortie reached Mach 1.2 and approximately 49,000 feet.
X-59 had already reached Mach 1.4 at about 55,000 feet on June 12. Flight 25’s Mach 1.2 was a test point, not a new speed record. NASA’s June milestone report.
Flight measurements have closely matched predictions for controllability, stability margins and structural loads. The team also compares incoming flight data with a real-time digital twin to check the aircraft against its simulated behavior.
This milestone does not yet demonstrate the aircraft's quiet sonic signature. A chase aircraft accompanied the tests and its booms masked the X-59's sound. NASA says a later phase will measure the low-boom design itself, ahead of the community-response work planned for Quesst.
Primary source: NASA Quesst flight update. Report published 2026-09-04; summary checked 2026-09-08.