NASA’s X-59 quiet supersonic research aircraft is preparing for some of its most significant flights yet. The X-plane is about to begin a new block of test flights that will include its first time flying faster than the speed of sound and other mission-critical objectives.

“What comes next is the first time this one-of-a-kind aircraft will fly supersonic,” said Cathy Bahm, project manager for NASA’s Low Boom Flight Demonstrator. “We are starting toward the mission conditions test point that X-59 was designed for.”

After months of flights, the X-59 team reviewed their progress in late May and now look toward the aircraft’s next series of flight tests, including higher altitudes and faster speeds. This will give engineers a look at how the X-59 handles under required operational conditions for NASA’s Quesst mission to eventually gather data on quiet supersonic flight.

The team expects the X-59 to fly supersonic – over 630 mph – for the first time at approximately 43,000 feet altitude during a series of test flights in early June, a major milestone for the aircraft. After that, it will conduct a “mission conditions” flight, where it will hit Mach 1.4 (925 mph) at approximately 55,000 feet. That speed and altitude are important because they’re NASA’s performance targets for the X-59 to eventually fly over U.S. communities to demonstrate quiet supersonic flight and collect feedback data about the aircraft’s quiet sonic “thump” from the public.

While the X-59 is designed to fly at supersonic speeds without producing a loud sonic boom, these early flights are not yet intended to demonstrate its quiet supersonic capabilities. The X-59 will be accompanied by a traditional supersonic chase plane, so any quiet thump it produces in the current phase of testing will be obscured by louder, traditional sonic booms from the chase. In supersonic flights this summer, the chase aircraft will also be outfitted with a specialized shock-sensing probe to take initial measurements of the X-59’s shock waves.

The X-59’s first block of flights successfully met several test goals, generating data for its team to analyze. After making its first flight in October 2025, it entered a scheduled period of maintenance before returning to the skies in March 2026. It has since completed 14 additional flights, marking milestones including:

• Its first gear swing, or the retraction of its landing gear to show off its sleek design for the first time.
• Reaching altitudes up to 43,000 feet and near supersonic speeds at Mach 0.95, approximately 627 mph. 
• Marking its first dual-flight day and then making those increasingly routine as the X-59 team increased flight cadence.
• After a period of moving higher and faster, transitioning into lower and slower test flight conditions so engineers could gather information on the X-59’s behavior across a range of flight conditions. 

Data collected during the X-59’s first block of test flights helped teams better assess critical systems, including fuel, hydraulics, environmental controls, and the eXternal Vision System, which is the aircraft’s unique series of cameras that feed into a monitor that allows the pilot to see forward instead of using a traditional windshield. Teams monitored how the aircraft behaved during takeoff, landing, and throughout flight. Strain gauges installed throughout the X-59 collected detailed information on the forces it experienced, and how its structure responded to them.  

During the X-59’s upcoming flights, pilots will run through test points while engineers watch the aircraft’s performance — but now in supersonic flight conditions. 

“Flying at supersonic speeds is a major milestone for the X-59 team,” Bahm said. “Every step of envelope expansion brings us closer to demonstrating the quiet supersonic capability that is at the heart of the Quesst mission. Completing the first mission-conditions flight is especially meaningful – it’s the moment where we begin validating the aircraft in the environment it was designed for.”

In addition to reaching mission condition during this block of flight tests, the X-59 will also achieve its maximum speed of Mach 1.6 (1,218 mph) and altitude of 60,000 feet.

But just because the aircraft can go that fast doesn’t mean it always will fly supersonic. Testing will continue, including a mix of subsonic and lower-altitude flights so the team can continue monitoring it in varied conditions.

“These flights not only deepen our confidence in the X-59’s performance – they mark our progression toward the future phases of the mission that will ultimately help shape the future of supersonic travel,” Bahm said.

All flights so far and in the upcoming test block are part of Phase 1 of the X-59’s Quesst mission, focused on proving the performance and airworthiness of the aircraft. Some of those flights will include early deployment of equipment, including a probe mounted to one of NASA’s F-15 research aircraft that can measure the X-59’s unique shock wave signature.

Data gathered during those early probing flights will allow engineers to prepare for a new stage of work set to begin later this year: Quesst Phase 2, when teams will begin to measure the aircraft’s supersonic flight signature to verify that it’s producing a quiet supersonic thump, as designed.

“Aviation pioneer Otto Lilienthal said, ‘To design a flying machine is nothing. To build one is something. But to fly is everything.’ The 15 X-59 flights we’ve accomplished since March have been everything to this team and the mission,” Bahm said. “Every flight has pushed the boundaries of what’s possible, steadily expanding the envelope and strengthening our confidence in the aircraft.”

But, she said, rather than focusing on past progress, the team is already looking ahead.

“As we look ahead to the upcoming flights, we’re poised to open the envelope even further – moving boldly toward the mission test point this aircraft was built to achieve,” Bahm said. “Flying supersonic and reaching these milestones isn’t just progress; it’s the realization of years of perseverance, innovation, and teamwork. Each step brings us closer to Phase 2, and to the future of commercial supersonic flight.”