WASHINGTON (AP) — President Joe Biden has picked a longtime government official and current top aide in the Transportation Department to serve as acting administrator of the Federal Aviation Administration.

The White House said Thursday that Polly Trottenberg replaced Billy Nolen, who indicated in April that he planned to leave the FAA.

Trottenberg held a high-ranking job in the Transportation Department during the Obama administration and has most recently been deputy to Transportation Secretary Pete Buttigieg. She headed the New York City Transportation Department from 2014 to 2020 and worked as a U.S. Senate aide and at the Port Authority of New York and New Jersey.

The FAA, which manages air traffic throughout the nation, has been without a Senate-confirmed leader since March of last year, when Stephen Dickson resigned halfway through his five-year term. Since then, the agency has faced understaffing of air traffic controllers, a technical outage that grounded flights nationwide in January, and several close calls between airline jets.

Biden's nominee to replace Dickson withdrew this year when it became clear that he would not be confirmed. Republicans said Phil Washington lacked enough aviation experience to run the FAA.

The White House said the administration is conducting a national search for a new nominee.