WASHINGTON (Reuters) - The U.S. Senate is set to vote on Wednesday to confirm a former airline executive to head the Federal Aviation Administration.

Safety concerns are an issue at the FAA, which is grappling with a review of Boeing Co’s grounded 737 MAX in the wake of two crashes that killed 346 in October and March, as well as broader questions about how it certifies aircraft and whether it delegates too much authority to manufacturers.

The FAA faced questions about why it lagged other countries in grounding the 737 MAX and has repeatedly said it will not allow the plane to fly again until it is safe to do so.

The Senate voted 52 to 45 Tuesday to end debate and advance former Delta Air Lines executive Stephen Dickson’s nomination. The FAA has been without a Senate-confirmed chief for more than 18 months.

This month, the Senate Commerce Committee voted 14 to 12 along party lines to approve the nomination.

Senator Maria Cantwell, the top Democrat on the panel, brought up the issue of Delta’s treatment during Dickson’s tenure of a whistleblower pilot who raised concerns about pilot training on the A-330 when it came to automation and ensuring that pilots were getting enough rest time.

“He is not the right person for the safety culture that we need at the FAA,” Cantwell said on Tuesday on the Senate floor.

Committee Chairman Roger Wicker, a Republican, said earlier the panel spent two months “reviewing any and all information” about the issue. Dickson was never accused of retaliating against any whistleblower, Wicker said.

U.S. President Donald Trump in March said he would nominate Dickson to run the 45,000-employee agency, which oversees U.S. airspace. Dickson left Delta in October after 27 years.

The FAA, which has been run by an acting chief Dan Elwell since January 2018, faces mounting questions from federal prosecutors, lawmakers and the Transportation Department’s inspector general over its certification of the 737 MAX.

The FAA is not expected to allow the planes to fly until October at the earliest.

If Dickson is confirmed, Elwell will need a waiver from Congress to be his deputy because they are both former U.S. military officers.

Dickson’s nomination had been in the works for months before the March 10 Ethiopian Airlines crash.

The FAA is also dealing with such issues as integrating drones into the nation’s airspace, modernizing air traffic control and setting minimum rest periods for airline flight attendants.