Boeing is conducting a final certification test flight of a 787 today with an improved battery design, as the airframer works to return the grounded aircraft type to commercial service.
The flight, operated by a LOT-ordered 787, departed Paine Field in Everett, Washington at 10:39 and is scheduled to land at 12:37 local time.
Boeing completed a functional flight test with the same aircraft on 25 March.
Following today's flight, the US Federal Aviation Administration (FAA) still has to approve the flight and ground tests of Boeing's improved battery design before the aircraft can return to service.
The FAA grounded the 787 fleet on 16 January, prompting a worldwide grounding of the type.