NASA’s experimental X-59 aircraft achieved a significant milestone on Friday, June 5, by flying faster than the speed of sound for the first time. This achievement sets the stage for demonstrating its quiet supersonic capabilities later this year.
Piloted by NASA test pilot Jim “Clue” Less, the aircraft took off and landed at Edwards Air Force Base in California. During the flight, the X-59 reached a top speed of approximately Mach 1.1 (713 mph) at an altitude of 43,400 feet. The flight, which began at 11:08 a.m. PDT and lasted 81 minutes, focused on evaluating the aircraft’s flying qualities at both subsonic and supersonic speeds.
“The X-59 is getting ready for its quiet supersonic debut,” said NASA Administrator Jared Isaacman. “Since the aircraft’s first flight on Oct. 28, 2025, the team has made tremendous progress, flying 16 times in the last 90 days and getting into a steady test rhythm. In the coming days, we expect to take the next step and push to Mach 1.4.” He added, “I’m grateful to the NASA team and Lockheed Martin Skunk Works for their help getting us to this point, and I hope this is the first of many collaborations as we rebuild NASA’s X-plane portfolio.”
The X-59 is engineered to fly at supersonic speeds while producing only a quiet thump, rather than a loud sonic boom. For this initial supersonic flight, a NASA F-15 chase plane accompanied the X-59 to monitor its performance. The loud sonic booms from the F-15 obscured any sound generated by the X-59.
Michael Kratsios, Assistant to the President for Science and Technology and Director of the Office of Science and Technology Policy, stated, “The X-59’s first supersonic flight is a testament to America’s enduring leadership in science, engineering, and aerospace innovation. This achievement comes as the Trump Administration continues work to unleash supersonic flight and enable American ingenuity.”
While this first supersonic flight is a critical step, an even more important mission flight is anticipated soon. The aircraft is expected to undertake its first “mission conditions” flight within days, aiming for a cruising speed of Mach 1.4 (925 mph) at an altitude of approximately 55,000 feet. A chase plane will also accompany the X-59 during this flight.
These speed and altitude parameters are foundational for the X-59’s future flights over several U.S. communities. These flights will enable NASA to collect data on how people perceive its quiet thump. NASA plans to share this data with U.S. and international regulators to assist in establishing new, data-driven noise standards, thereby fostering a viable future market for supersonic commercial flight over land.
Over the past several months, the X-59 has been engaged in an ongoing series of flights, a process known as envelope expansion. During these flights, the aircraft has operated at a wide range of speeds and altitudes. These tests represent the initial phase of the X-59’s flight testing, concentrating on performance and involving chase plane monitoring. Upon completion of this phase, the aircraft will move to another focused on its sound profile to confirm its quiet thump capability.
The X-59 is central to NASA’s Quesst mission, which endeavors to demonstrate quiet supersonic flight and facilitate commercial supersonic flight over land globally. These advancements are intended to enable travelers to reach their destinations more quickly, reducing air time.
Through the Quesst mission’s development of the X-59, NASA will also provide design tools and technology for quiet supersonic airliners capable of achieving high speeds desired by commercial operators without causing disturbances on the ground. NASA will validate these design tools through ground and flight testing, equipping U.S. aircraft manufacturers with the ability to explore new quiet supersonic concepts and providing them with confidence that their designs will meet quiet flight requirements.
