Is the flying public ready to re-embrace the Boeing 787 Dreamliner? Three months after the plane was grounded, it’s set to return to the skies even though the root cause of its battery trouble remains unknown.

In early March, Boeing expressed confidence that it had eliminated all risk of battery fires with a redesigned cell and a casing that safely releases heat and pressure.

“I feel more confident in the performance of the product now because we’ve addressed many possible things than if we would have only just addressed one thing,” Michael Sinnett, vice president and chief project engineer of Boeing’s commercial airplane division, said at a news conference in Tokyo as the U.S. company pitched its remedy for the aircraft’s troubled lithium-ion battery.

Sinnett termed the airplane “absolutely” safe and said he would “gladly” have his family fly in it.

The U.S. Federal Aviation Administration’s move last Friday to approve Boeing’s design modifications for the battery system came two weeks after the company conducted a test flight of the 787 with an improved lithium-ion battery.

United Airlines, the only U.S. airline with 787s in its fleet, is looking to resume flights in late May.

The FAA decision also frees Boeing to restart delivering the 787. Boeing said it will likely be able to complete all of this year’s planned deliveries of the fuel-efficient jet and the battery issue “will have no significant impact to its 2013 financial guidance.”

Japanese regulators are also expected to allow Japanese carriers to put the 787 back in the air in the very near future. All Nippon Airways Co. and Japan Airlines Co. — the world’s two largest buyers of the 787 — have already begun replacing batteries with modified ones, striving to get the advanced aircraft back in service as early as June.

However, aviation experts say concerns over the aircraft’s safety will linger as U.S. and Japanese transport authorities have yet to complete their investigation into what caused the batteries to overheat in the first place.

When an ANA-operated Dreamliner was forced to make an emergency landing Jan. 16 due to smoke in the cockpit, some aviation experts said it would take up to a year to pin down the cause. The investigation does not appear to have made significant progress so far.

The FAA’s green light for the 787 to fly again came “much sooner than expected” due to political pressure, said Hajime Tozaki, a Waseda University professor specializing in transportation policy.

“Boeing’s planes are one of the biggest exports from the United States. A further delay in the resumption of the 787 operations would have dealt a huge blow” to the country as well as Boeing’s earnings, Tozaki said.

To address lingering safety concerns, ANA and JAL are considering voluntary safety measures for the aircraft, such as enhancing monitoring of battery voltage levels.

ANA President Osamu Shinobe said in a recent interview that the carrier stands ready to explain to its customers the details of the 787 incident as well as the safety of the airplane.

“We will take into account how our customers and the media will react, but what Boeing told us was that they have addressed all possibilities, and there are absolutely no problems even though we don’t know whether multiple factors are behind (the incident) or if there is a single root cause,” Shinobe said.

Tozaki, however, said that wary customers may refrain from traveling on the aircraft for the time being even after regulatory approvals.

“Passengers will react sensitively if any mishaps involving the 787 were to occur again, even if they aren’t as serious as the battery problems. Carriers will have to operate their 787s with meticulous care,” he said.