4 Test Aircraft: The Specific Roles Of Boeing’s 777X Prototypes

US aircraft manufacturer Boeing’s testing program for its upcoming 777X flagship widebody is well underway. The manufacturer has completed four test aircraft, each with a different role in the certification process and set of test equipment. The planes are registered to highlight the 777-9X designation uniquely and are given sequential final letters corresponding to the last letters of the alphabet. Collectively, they have completed over 3,500 hours of flight tests across 1,200 sorties in preparation for FAA certification, which began last month.