NASA’s experimental X-59 aircraft has reached another major milestone, completing its 25th test flight as the agency moves closer to demonstrating a new way to fly faster than sound without producing the deafening sonic booms associated with traditional supersonic aircraft.

The X-59 is the centerpiece of NASA’s Quesst mission, an ambitious project designed to determine whether supersonic passenger flights could one day return over land with much quieter noise.

25 flights and counting

The X-59 completed its 25th flight on August 21, 2026, taking off from NASA’s Armstrong Flight Research Center in Edwards, California.

The flight lasted 72 minutes, with the aircraft reaching approximately 49,000 feet (14,900 meters) and a speed of Mach 1.2 — about 1.2 times the speed of sound.

A chase aircraft accompanied the X-59 during the flight to monitor its performance. Because the chase aircraft itself produces conventional sonic booms, NASA has not yet used these flights to evaluate the X-59’s quieter sound signature.

Instead, the first 25 flights have focused primarily on making sure the aircraft performs as expected.

The X-59 is behaving almost exactly as predicted

One of the most encouraging results from the test campaign is how closely the aircraft’s real-world behavior matches NASA’s computer simulations and wind-tunnel predictions.

Engineers have been monitoring several important characteristics, including:

• How easily the aircraft can be controlled

• How stable it remains during flight

• The forces and stresses acting on the aircraft

• How its systems respond during different maneuvers and conditions

So far, NASA says the X-59 has not experienced unexpected problems such as instability or excessive vibration caused by aerodynamic forces.

The team is also using a real-time digital twin to compare actual flight data with simulated predictions.

This allows engineers to see how closely the real aircraft behaves compared with the models that were developed before it ever took to the sky.

Faster than sound — without the huge boom

Traditional supersonic aircraft create powerful shock waves that reach the ground as loud sonic booms.

The X-59 was designed differently.

Its extremely long, slender nose and carefully shaped airframe are intended to spread out those shock waves rather than allowing them to combine into one explosive boom.

Instead of a thunderous crack, NASA hopes people on the ground will hear something closer to a quiet “thump.”

That difference could be extremely important.

Current restrictions on civilian supersonic flight over land are largely connected to the noise produced by sonic booms. If NASA can demonstrate that supersonic aircraft can fly overhead without creating disruptive noise, it could provide regulators with new data for reconsidering those restrictions.

The X-59 has already reached Mach 1.4

The aircraft has progressed significantly since its early test flights.

NASA says the X-59 reached its target cruise speed of Mach 1.4, approximately 924 mph (1,487 km/h), relatively early in its testing program.

It has also reached its target altitude of approximately 55,000 feet.

The team has since been expanding the aircraft’s flight envelope — testing how it performs across different speeds, altitudes and operating conditions.

Even the aircraft’s unique engine-air intake system has performed as expected during different maneuvers and conditions.

Between flights, engineers, pilots and maintenance crews carefully analyze the collected data and make small adjustments where necessary.

The most important tests are still ahead

Although completing 25 flights is an important achievement, NASA says the most significant part of the mission is approaching.

The next major phase will focus on acoustic validation.

During these flights, NASA will use instruments on the ground and in the air to measure the sound generated by the X-59 as it travels faster than sound.

The goal is to determine whether the aircraft actually produces the quiet sonic “thump” that engineers designed it to create.

“This is the phase we’ve been working toward,” said Larry Cliatt, NASA’s acoustic validation technical lead for the Quesst mission.

The results could have implications far beyond the X-59 itself.

Could quiet supersonic travel return?

NASA’s ultimate goal is not to build a passenger aircraft with the X-59.

The X-59 is an experimental research aircraft and will not carry passengers.

Instead, NASA wants to collect scientific data that could help regulators establish new noise standards for supersonic flight over land.

After the acoustic tests, the X-59 is expected to fly over selected communities. People on the ground will then provide feedback about what they hear.

NASA plans to use this information to help regulators determine whether quieter supersonic flight could be acceptable to the public.

If successful, the research could eventually help open the door for a new generation of commercial supersonic aircraft capable of dramatically reducing travel times.

For now, the X-59 has completed 25 flights — and NASA’s quiet supersonic experiment is moving closer to its most important test yet.

The question is no longer simply whether an aircraft can fly faster than sound. It’s whether it can do so quietly enough for people on the ground.