Boeing still has to make “significant changes” to improve the quality and safety of its airplanes, according to the head of the Federal Aviation Administration.

The head of the Federal Aviation Administration told a U.S. House subcommittee Tuesday that safety culture improvements at Boeing may take three to five years to complete. "It is not a six-month program -- it is a three-year to five-year program,

The head of the Federal Aviation Administration will tell Congress on Tuesday the agency will hold Boeing accountable to ensure the planemaker is building safe airplanes and will revamp its own safety management program.