Boeing is finally flying back into positive headlines as it reactivates the fourth prototype of its next-generation widebody, the boeing 777x, for final-stage certification testing.

After a bumpy journey filled with delays and scrutiny, this latest development signals renewed momentum for the program.

The WH004 prototype (N779XZ) is now being prepped to join the FAA certification campaign. This aircraft will specifically handle evaluations of the Environmental Control System, ETOPS (Extended-range Twin-engine Operational Performance Standards), noise compliance, and general functionality and reliability.

These are critical steps to meet the FAA’s stringent safety and performance requirements before the aircraft can enter commercial service.

Active Testing Across Multiple 777X Prototypes

Boeing has been intensifying its certification efforts with multiple test aircraft in operation:

WH001: Brake & Crosswind Testing

• Conducted brake tests at Clinton-Sherman Airport (Oklahoma) on March 11.
• Underwent crosswind trials in Lubbock, Texas, on March 14, with winds reaching 60 knots.

WH002 & WH003: Continued Flight Testing

• WH002 was spotted in Moses Lake, Washington, on March 17.
• WH003 (N779XW), previously stationed in Roswell, New Mexico, moved to Clinton, Oklahoma, in early April for additional tests.

FAA Type Inspection Authorization (TIA) Granted

A major milestone was achieved in July 2024, when Boeing received Type Inspection Authorization (TIA) from the FAA. This allows FAA personnel to participate in official certification flights. Although testing was briefly paused in August 2024, operations have since resumed at full capacity.

Boeing aims to secure full type certification for the 777-9 by early 2026, enabling deliveries to begin that year. The program currently holds more than 480 orders, including variants like the 777-8 and the cargo-focused 777-8F.

This final phase of rigorous testing could mark the turning point Boeing has been working toward—one that brings the long-awaited b777x closer to reality for airlines and aviation enthusiasts alike.