Boeing's full complement of 787 test aircraft have returned to flight status, after aircraft three re-joined the flight test programme on 29 January.
The airframer has a total of six aircraft dedicated to flight testing.
ZA003 departed from Boeing Field where it had been in ground testing since its last flight on 28 November when it was ferried from the company's Everett, Washington facility north of Seattle.
The airframer resumed its own test operations on 23 December with its fourth flight test aircraft, and US Federal Aviation Administration certification flights on 16 January following a six-week stoppage after 9 November electrical fire aboard its second test aircraft in Laredo, Texas.
Boeing aims to deliver the first 787 aircraft to All Nippon Airways in the third quarter followed by 11 to 20 aircraft this year to an undisclosed number of customers.