X-59 QueSST: NASA's 'Quiet' Supersonic Jet Completes 1st Successful Test Flight

NASA's experimental X-59 QueSST (Quiet Supersonic Technology) jet successfully completed its first test flight on Tuesday, from Air Force Plant 42 in Palmdale, California, marking a major milestone in the development of quiet supersonic flight technology. The aircraft, designed to break the sound barrier without producing a disruptive sonic boom, took off at about 1413 UTC, flew at subsonic speeds and reached a peak altitude of 3,660 meters, as planned for its initial test phase.

The flight, which lasted about one hour, was conducted by NASA’s lead test pilot Nils Larson and was accompanied by a chase plane.

The X-59, a one-of-a-kind experimental aircraft designed by NASA and built by Lockheed Martin’s Skunk Works for NASA, is designed to cruise at Mach 1.4 (or 1,490 kph) at an altitude of 16,764 meters, more than twice as high and nearly twice as fast as conventional airliners.

Its unique, elongated shape is engineered to transform the explosive sonic boom into a much quieter "sonic thump," comparable in volume to slamming a car door, which could allow future supersonic commercial flights over land.

The first flight was a lower-altitude loop at about 386 kph to verify system integration, airworthiness, and safety, with subsequent flights planned to progressively increase altitude and speed until supersonic flight is achieved.

The test flight occurred after the U.S. Federal Aviation Administration (FAA) lifted its five-decade-old ban on supersonic flights over land in June 2025, paving the way for new noise-based certification standards.

NASA has invested over $518 million since 2018 in the X-59 program, and the aircraft was named 2025’s “Coolest Thing Made in California” by the California Manufacturers & Technology Association earlier this month.

The X-59 is equipped with an eXternal Vision System (XVS) to compensate for reduced forward visibility due to its long nose, and features a life support system, ejection seat, and g-suit for pilot safety.

The flight marks the transition from ground testing to airborne operations, with data collected from the X-59’s Flight Test Instrumentation System (FTIS) to inform future regulatory changes for supersonic flight.

If the X-59 can prove that "quiet" supersonic flight is possible, the restrictions on breaking the sound barrier above the populated U.S. could someday be lifted, allowing commercial supersonic flight.

After this first flight, the X-59 will now reside at NASA's Armstrong Flight Research Center, where it will undergo a testing campaign that will involve flying the jet over microphones placed throughout the desert and trailing other aircraft equipped with special air sensors through its shockwaves.

The QueSST program emerged in the mid-2010s as NASA's renewed push to enable overland supersonic flight by demonstrating boom mitigation viable for regulatory reconsideration, building on decades of low-boom research enabled by modern computational tools for precise pressure signature shaping.

In February 2016, NASA contracted Lockheed Martin's Skunk Works for the X-59's preliminary design phase, selecting the firm for its historical proficiency in secretive, high-performance experimental programs such as the SR-71 Blackbird and F-117 Nighthawk.