Boeing Co has high confidence that the proposed fix for the lithium-ion batteries on its grounded 787 passenger jet will work, Chief Executive Officer Jim McNerney said on Thursday.

The grounding has been a “frustrating experience,” McNerney told a U.S. Chamber of Commerce aviation summit.

Regulators grounded the 787 on January 16 after separate battery incidents on planes in Boston and Japan. That grounding has already cost the company an estimated $450 million in lost income and compensation payments to airlines.

Boeing is now running test flights to prove the safety of its new battery system.

Shares of Boeing are up 16 percent since the plane was grounded. Most of that gain came over the last month as the 787 moved closer to flying again.

Reporting by Alwyn Scott. Editing by Gerald E. McCormick and Lisa Von Ah.

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Photo Credit: Boeing CEO Jim McNerney waits to be introduced to speak, in front of a Boeing 787 Dreamliner under construction at the Boeing facility in Everett, Washington February 17, 2012. Jason Reed / Reuters