U.S., Dec. 12 -- US civil aviation regulators are not likely to clear Boeing 's problem-prone 737 Max aircraft for flight until next year, according to the Administrator of Federal Aviation Administration Steve Dickson.

FAA chief said there is no clear timeline for when the agency will re-certify the 737 Max and that there are 10 to 11 milestones left to complete before it can be approved.

"Like I said there are a number of processes, milestones, that have to be completed," Dickson said, "If you just do the math, it's going to extend into 2020."

"We're going to follow every step of the process, however long that takes," he said. "I've made it clear that I'm going to support my people and that means they are going to take whatever time ...