Boeing has reactivated its fourth 777X testbed aircraft, designated WH004, marking its return to flight operations for the first time since late 2021.
The aircraft took off from Paine Field (KPAE) in Everett, Washington, on Wednesday. Following this flight, all four 777X test airplanes are now concurrently active, a milestone not achieved since 2021.
Registered as N779XZ, WH004 is uniquely configured with a full passenger interior, enabling it to conduct cabin-specific evaluations, including assessments of the environmental control system and interior noise levels, the aerospace giant said.
The aircraft had been stored to prioritize earlier testing phases on the other three test airplanes. In recent months, Boeing shared.
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“While the volume of changes to reactivate the airplane was challenging, our crew came together and focused on first-pass quality,” said Levi King, flight test maintenance lead at Boeing, in a company memo. “It’s rewarding to know what we accomplish together brings this important program closer to certification.”
It took to the skies again on a nearly three-hour flight from Everett to Moses Lake, then back to King County International-Boeing Field (KBFI) in Seattle.
Doubling Down on Testing
Boeing CEO Kelly Ortberg said on a recent earnings call that the manufacturer is ramping up 777X flight tests ahead of FAA certification.
“The aircraft are flying daily and performing well in flight testing,” Ortberg said.
Since January, Boeing has conducted 777-9 flight testing across various locations, including the Puget Sound, Curaçao, Montana, New Mexico, Oklahoma, Texas, and eastern Washington state.
To date, the 777X test program has completed over 1,400 flights, accumulating nearly 4,000 flight hours.
Boeing has received orders for more than 520 777X airplanes, encompassing the 777-9, 777-8 Freighter, and 777-8 passenger variants. The company is targeting the delivery of the first 777-9 in 2026.
