Ethiopian Airlines on Saturday became the first carrier to resume flying the Boeing 787 Dreamliners that have been grounded worldwide since January due to battery problems.
The Ethiopian carrier flew one of the next-generation aircraft from Addis Ababa to Nairobi, a day before All Nippon Airlines (ANA), which has the world's largest fleet of Dreamliners, is set to conduct a test flight in Japan.
"I am very happy to see the airplane is back in the air now and I am very happy also we are the first one," Ethiopian Airlines CEO, Tewolde Gebremariam told journalists before take off.
The US Federal Aviation Authority on Thursday issued a formal approval of Boeing's 787 battery fix, clearing the way for the troubled aircraft to fly again after the prolonged grounding.
The directive from the FAA to ground the 50 Dreamliners in operation worldwide came after a series of safety scares with the aircraft, including an emergency landing by ANA in January following a malfunction in a battery that provides auxiliary power.
Ethiopian Airlines has four Dreamliners, which Tewolde said would all resume service in the coming weeks after being retrofitted with new batteries.
"This is the first airplane which has completed the work," he told reporters, adding that work has already started on the company's other three 787s.
Each of the aircraft will receive an encased new battery, allowing the plane to continue flying in the event of a battery malfunction.
Even if the battery were to malfunction, "it's contained, it's isolated, the airplane will be able to continue flying," Boeing's marketing vice-president for commercial airplanes, Randy Tinseth, told AFP at the airport.
Despite the previous safety scares with the aircraft, he said customers have no reason to feel nervous about flying the Dreamliner.
"I can't wait to get back on the aircraft, and I wouldn't hesitate to bring my family on it," he said.
ANA, which already has 17 Dreamliners -- the world's largest fleet -- and dozens more on order, will test one of its modified Dreamliners on Sunday.
The ANA flight, to and from Tokyo's Haneda airport, will have the company's chairman Shinichiro Ito and Boeing's CEO Ray Conner on board, with both of them anxious to put the damaging crisis behind them.
ANA and domestic rival Japan Airlines (JAL) account for around half the 50 Dreamliners in service worldwide, but it could still be at least a month before they can complete all the battery fixes and get their planes in the air.
-- Cause of battery failure still unknown --
Although the exact cause of the battery failures had yet to be pinpointed -- as noted by the FAA on Thursday -- Mike Sinnett, Boeing's chief project manager for the Dreamliner programme, insisted the refitted planes were safe to fly.
"Even if we missed the root cause, we have identified 80 potential causal factors and we have addressed all of them in the design," he said on Saturday in Tokyo.
Sinnett said the Japanese civil aviation authorities had expressed their belief that "any potential causes have been addressed in our solution. We still know that even if we missed something, the airplane remains absolutely safe".
He explained that the solution for the batteries eliminated the potential for fire and heat to get into the airplane. "No matter what happens to the battery, regardless of the root cause, the airplane is safe," he said.
The three-month grounding has been damaging to Boeing's reputation.
Eight airlines worldwide operate the Dreamliner. Ethiopian Airlines was the first African carrier to acquire the plane.
The 787 heads back to Addis Ababa -- some 1160 kilometres (720 miles) from the Kenyan capital -- Saturday evening, with the flight taking around two hours -- airline officials said.
"(There are) 50 airplanes on the ground with our customers, those airplanes are in the process of being modified, the bulk of those will return to the air by mid-May," Boeing's Tinseth said.
"Our expectation is to deliver 60 or more 787s this year," he said.
Apart from the two Japanese carriers and Ethiopian, the other companies that operate the Dreamliner are United Airlines, Qatar Airways, Chile's LAN, Air India and Polish flag carrier LOT.
The passengers on Saturday's flight were for the most part unaware they were flying on the Dreamliner.
One of them, Francois Vaillancourt told AFP he was "not at all" nervous.
"Airlines are safest after they've had a problem, so they fixed it and it is probably three times as safe as it was before," he said.