Boeing has been given permission by the US Federal Aviation Administration to carry out test flights of its 787 Dreamliner aircraft.
It has been allowed to run test flights "in defined airspace over unpopulated areas" and only after extensive pre-flight testing and inspections.
It is hoped the flights will help collect vital airborne data about the performance of the aircraft’s batteries.
Boeing and its airline customers were ordered to ground the entire fleet of 787s last month after two incidents involving the battery.
In one, a battery on the plane caught fire while another flight was forced to make an emergency landing when the battery malfunctioned.
Meanwhile, another US regulator, the National Transportation Safety Board (NTSB), said the initial tests carried out by Boeing on the Dreamliner batteries missed the high risk of fire.
NTSB head, Deborah Hersman, said initial safety checks and approval were given under the assumption that the lithium-ion batteries would produce smoke less than once in every 10 million flight hours.
But there have already been two battery fires since the 787 entered commercial service, in which time it has only clocked up 100,000 hours of flight-time.
The NTSB said Boeing’s tests also overlooked the fact that overheating in one battery cell could spread to the others, causing a fire.
Both of these issues need to be readdressed, said Hersman.
The NTSB hopes to produce an interim factual report within 30 days, but it will not be a final report.
TUI is due to take delivery of the Dreamliner in May.
