WASHINGTON- Boeing reactivated its fourth 777X test aircraft on April 13, 2025, at Seattle Paine Field International Airport (PAE). The airframe, known as WH0004 and registered as N779XZ, had its transponder activated with the callsign ‘BOE777‘ from approximately 09:49 to 11:32 local time.
This development marks a significant step for the aircraft, which had remained grounded at Seattle Paine Field since November 2021, when it last operated a flight from King County International Airport (BFI).
Photo: BoeingBoeing’s 777X Test Plane
The first 3 777-9 test airframes have been actively flying since January 2025 as Boeing resumed its certification campaign. Simple Flying reported that the aircraft, designated as WH001 (N779XW), WH002 (N779XX), and WH003 (N779XY), have been conducting regular test flights after addressing technical issues that had previously interrupted the certification process.
Boeing’s 777X program faced delays when problems with the aircraft’s thrust links—structural components connecting the engine to the airframe—essentially grounded the certification efforts. WH003 was the first aircraft to experience cracked engine thrust links, which suspended flights until January 2025.
The certification program had previously advanced to the Type Inspection Authorisation stage before these issues arose.
Photo: Clément AlloingFlight records show that WH001 operated its first flight on January 23, 2025, travelling from Paine Field (PAE) to Moses Lake Grant County International Airport (MWH). WH002 resumed flying on February 5, making its first journey since August 2024. WH003 returned to the skies on January 16, departing and landing at Boeing Field (BFI). All three aircraft conducted their most recent test flights on April 11, 2025.
#UPDATE: WH001 (N779XW) is returning home (BFI) after over a month of FAA certification testing in Clinton Sherman, OK.
Track flight: https://t.co/DNW1Dx1Y4P#777X #GE9X #Boeing777x #777X pic.twitter.com/wsnMVz92TU
— Boeing 777X (@b777xlovers) April 18, 2025
Boeing’s Everett production site, where the company assembles widebody aircraft, has undergone significant changes in recent years. Following the end of 747-8 production in January 2023, Boeing announced plans to establish a fourth 737 MAX production line at the facility.
However, the FAA later prohibited the expansion of production or additional lines until Boeing improves aircraft quality, a position supported by Department of Transportation officials.
Boeing Field; Photo- WikipediaCertification and Timeline
During the Bank of America Global Industrials Conference on March 19, 2025, Boeing’s Executive Vice President and Chief Financial Officer, Brian West, revealed that the FAA had approved the second phase of 777-9 flight testing. This phase focuses on aerodynamics, brakes, and engine certification. At that point, the 777-9 had accumulated 3,700 flight test hours.
On January 28, 2025, during Boeing’s Q4 2024 earnings call, CEO Kelly Ortberg confirmed that the timelines for the 777X, 737 MAX 7, and 737 MAX 10 remain unchanged.
Boeing still aims to certify all three aircraft in 2025, with the first 777-9 scheduled for delivery to Lufthansa (LH). The company plans to disclose its Q1 2025 results on April 23, having already announced the delivery of 130 commercial aircraft during the quarter.
Photo: By Dan Nevill from Seattle, WA, United States; Wikimedia CommonsAbout the 777X
The Boeing 777X represents the latest generation of the Boeing 777 family, which holds the distinction of being the most-produced widebody aircraft and the largest commercial plane currently manufactured.
Boeing is developing three versions: the 777-8, 777-8F, and 777-9, with each designed to enhance passenger comfort.
The aircraft has secured 379 orders from 9 different customers, not counting the 4 test aircraft built for Boeing’s development program.
The 777-8 passenger version appears less popular, attracting only Emirates (EK) and Etihad Airways (EY) as customers. Among the airlines ordering the 777X series, Air India (AI) has committed to purchasing 10 of the 777-9 variant.
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Boeing Begins 777X Brake testing as Part of FAA Certifications Flights
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