MD-Jet Arrives at Boeing Site for Transformative Modification: Sustainable Aviation Advances

By Sophia Francise

August 19, 2023

On Thursday, Boeing announced that it had ferried an MD-90 airplane from Victorville, California, to its Palmdale facility, where it will be modified to test the Transonic Truss-Braced Wing (TTBW) configuration.

The transfer marks a milestone in NASA’s Sustainable Flight Demonstrator project and marks progress toward a potential new era of aviation.

The X-66A is NASA’s first experimental plane focused on helping the U.S. achieve its net-zero aviation greenhouse gas emissions goal. The modification will begin soon, and ground and flight testing will begin in 2028.

The NASA-Boeing Collaboration Explained

The MD-90 will undergo key modification involving the replacement of its wings with a new set that boasts a sleeker, elongated design supported by diagonal struts. 

With ultrathin wings braced by struts with larger spans and higher-aspect ratios, the TTBW design and other expected technological advances could reduce fuel use and emissions by up to 30%.1

This innovative concept, known as the Transonic Truss-Braced Wing configuration, promises to enhance fuel efficiency compared to existing top-tier commercial aircraft.

Boeing and NASA have collaborated on the concept through the Subsonic Ultra Green Aircraft Research (SUGAR) Program for over a decade.

Collaborating with NASA, Boeing is embarking on the construction, testing, and flight of the X-66A, which will serve as a full-scale test aircraft. 

“This marks an important step in the Sustainable Flight Demonstrator project, advances Boeing’s commitment to sustainability, and brings us closer to testing and validating the TTBW design,” said Boeing Chief Technology Officer Todd Citron.

The X-66A’s primary objective aligns with the United States’ ambitious net-zero aviation greenhouse gas emissions goal, as outlined in the US Aviation Climate Action Plan proposed by the White House.

Notably, the X-66A is the inaugural X-plane specifically engineered to contribute to achieving net-zero aviation greenhouse gas emissions. 

This effort underscores the joint commitment of NASA and Boeing to advance sustainable aviation technologies and support broader environmental goals.


“We at NASA are excited to be working with Boeing on the X-66A Sustainable Flight Demonstrator making critical contributions to accelerate aviation towards its 2050 net-zero greenhouse gas emission goal,” said Ed Waggoner, deputy associate administrator for programs in the NASA Aeronautics Research Mission Directorate.


  1. Boeing Media Room, ‘Airplane Arrives at Boeing Site for X-66A Modification’, 17 August 2023,[]