Dreamliner is declared safe; flights resumed Boeing Co.'s 787 Dreamliner jet, which resumed flights after a more than three-month hiatus, is safe even though the cause of a battery defect remains uncertain, the aircraft manufacturer said. Ethiopian Airlines Enterprise on Saturday made the first 787 flight since the grounding, traveling from Ethiopia's capital, Addis Ababa, to Nairobi, Kenya. ANA Holdings Inc., the world's largest operator of the Dreamliner planes, plans to have a test flight Sunday. The planes have been prevented from flying worldwide since Jan. 16 after lithium ion batteries on two planes overheated and melted, leading to the longest grounding of a large commercial aircraft by U.S. and Japanese regulators since commercial jetliners were introduced in the 1950s. Boeing won approval this month from the Federal Aviation Administration for the 787's redesigned battery system. The Japanese government also approved the restart of 787 flights, the Transport Ministry said Friday. The permission will be for all flights, including test and commercial services, according to Shigeru Takano, a director at the ministry's Civil Aviation Bureau. Ethiopian Airlines Chief Executive Tewolde Gebremariam and Randy Tinseth, Boeing's vice president of marketing, were on board the 787 flight Saturday. Chicago-based Boeing's reworked battery includes more protection around the cells to contain overheating, a steel case to prevent any fire from spreading and a tube that vents fumes outside the fuselage. ANA and Japan Airlines additionally have put in place a system to monitor the batteries during flights and transmit data to the ground. Neither the FAA nor the National Transportation Safety Board has determined what caused the battery faults that sparked a Jan. 7 fire on a Japan Airlines 787 in Boston and forced an emergency landing by an ANA 787 in Japan nine days later. The Dreamliner is the only large commercial jet equipped with lithium ion batteries as part of its power system.