WASHINGTON (Reuters) – The Biden administration on Saturday named the Federal Aviation Administration’s (FAA) safety chief as the acting leader of the agency effective Friday.

In December, Billy Nolen was named the FAA’s associate administrator for aviation safety and had previously been vice president for safety, security and quality for WestJet Airlines in Canada.

Nolen, who started his career as an American Airlines AAL.O pilot, will replace FAA administrator Steve Dickson, who is stepping down on March 31 until the White House nominates a permanent successor.

“Billy Nolen has extensive expertise in aviation and a deep understanding of the vital role the FAA plays in ensuring the safety of the traveling public,” said U.S Transportation Secretary Pete Buttigieg.

Nolen leads a team of more than 7,600 FAA employees. The FAA’s safety efforts and oversight of Boeing BA.N have come under fire after two fatal 737 MAX crashes in a five-month period killed 346 people and led to the plane’s 20-month grounding. Congress in December 2020 passed legislation to reform how the FAA certifies new airplanes and delegates some duties to manufacturers like Boeing.

Dickson, 64, is resigning about halfway through his five-year term. The Biden administration “is conducting a national search for a nominee to become the permanent FAA administrator,” the FAA said Saturday.

Dickson headed the FAA as it oversaw a comprehensive review of the then-grounded Boeing 737 MAX. He took a hard line, warning in late 2019 that Boeing was pursuing “a return-to-service schedule that is not realistic.”

Earlier this week, the FAA warned Boeing it may not gain certification of a lengthened version of the 737 MAX ahead of a key safety deadline set by Congress and also sought updates on progress for both the 737 MAX 10 and 777-9, Reuters reported Friday.

The FAA is still scrutinizing a number of issues involving Boeing and last month said it would not allow Boeing to self-certify 787 Dreamliners.

Nolen will face the headache of the 5G wireless deployment using C-Band spectrum, an issue that saw major international airlines scramble to cancel some U.S flights amid warnings the network could interfere with sensitive aviation electronics. As a result, Nolen has been in ongoing discussions with telecom and aviation industry officials.

The FAA also said Saturday that Deputy FAA Administrator Bradley Mims “will also take on an expanded role during this interim period, focusing on the FAA’s workforce and the nation’s airports.”