UPDATE 1-FAA chief has no timetable for Boeing 737 MAX approval

The acting head of the Federal Aviation Administration said on Wednesday he does not have a specific timetable to approve Boeing Co's 737 MAX for flight after two fatal crashes since October prompted the plane to be grounded worldwide. The FAA is meeting with more than 30 international air regulators including China, the European Union, Brazil and Canada on Thursday to discuss a software fix and new pilot training that Boeing has been developing to ensure the jets are safe to fly.

"It's a constant give and take until it is exactly right," Dan Elwell told reporters. "It's taking as long as it takes to be right," he said, adding: "I'm not tied to a timetable." Asked if it is realistic that the 737 MAX could be flying again by August, Elwell declined to be specific.

"If you said October I wouldn't even say that, only because we haven't finished determining exactly what the training requirements will be," Elwell said. "If it takes a year to find everything we need to give us the confidence to lift the (grounding) order so be it." Elwell said he plans to share the FAA's "safety analysis that will form the basis for our return to service decision process" on Thursday. But he said the agency is still waiting for Boeing to formally submit the software upgrade for approval, and emphasized the FAA has not decided on the revised training requirements, including whether to require simulator training. (Reporting By Allison Lampert in Montreal and David Shepardson in Fort Worth, Texas Additional reporting and writing by Tracy Rucinski in Chicago Editing by Susan Thomas and Sonya Hepinstall)