WASHINGTON, Aug 7 (Reuters) - The head of the National

Transportation Safety Board said on Wednesday the Alaska

Airlines Boeing 737 MAX 9 mid-air emergency was

entirely avoidable because the planemaker should have addressed

unauthorized production work long ago.

"This accident should have never happened. This should have

been caught years before," NTSB Chair Jennifer Homendy told

reporters.

"There have been numerous, numerous Boeing ( BA ) audits, FAA

audits, compliance reviews, compliance actions plans, noting a

history of an unauthorized work, unauthorized removals," Homendy

said.