The leader of the Federal Aviation Administration, whose agency has been criticized for its oversight of Boeing and handling of questions surrounding 5G interference with aircraft, said Wednesday he will step down March 31.

Stephen Dickson, a former pilot and executive with Delta Air Lines in Atlanta, had led the FAA since August 2019. He citied separation from his family during the pandemic, saying he told President Joe Biden, "It is time to go home."

In a letter to FAA staff, Dickson said he was proud of his tenure.

"The agency is in a better place than it was two years ago, and we are positioned for great success," he said.

Transportation Secretary Pete Buttigieg, whose department includes the FAA, said the 64-year-old Dickson "has been the FAA's steady and skilled captain."

In a statement, Buttigieg said Dickson's tenure "has been marked by steadfast commitment to the FAA's safety mission ... and his lifelong dedication to making sure our aviation system is the best and safest in the world."

The White House had no immediate comment on a successor.

The FAA's reputation was battered before Dickson became administrator. The agency was questioned about how it approved the Boeing 737 Max and criticized for not grounding it after the first of two deadly accidents in 2018 and 2019.

When the CEO of Boeing seemed to pressure the FAA by saying several times that the agency would soon clear the plane to fly again, Dickson pushed back in November 2019.

Dickson released a video in which he told FAA technical experts: "Now I know there's a lot of pressure to return this aircraft to service quickly ... I want you to take the time you need and focus solely on safety. I've got your back."

The FAA finally cleared the plane in late 2020 after grounding it for nearly two years while Boeing overhauled an automated flight-control system that played a role in the crashes.

However, that did not end criticism over the FAA's oversight of Boeing. Relatives of passengers who died in the Max crashes pushed for Dickson's removal. Last week, Democrats who lead the House Transportation Committee and its aviation subcommittee asked for an inspector general's report into why the FAA didn't take more enforcement action against Boeing for problems with the plane.

Also in recent weeks, the FAA has been swept up in controversy over whether new high-speed wireless service from AT&T and Verizon can interfere with instruments on planes. Under pressure from the FAA, the Transportation Department and the White House, the telecommunications companies agreed to delay their rollout of the service near busy airports. Critics, however, said the FAA was slow to take up the issue.

Rep. Sam Graves of Missouri, the top Republican on the House Transportation Committee, said Dickson worked to restore public confidence in the U.S. aviation system "at a difficult time for the agency." He said Dickson was putting into effect improvements in the system for certifying new aircraft.

Dickson was a U.S. Air Force pilot before joining Delta, where he rose to senior vice president of flight operations before President Donald Trump nominated him to lead the FAA. The Senate vote was a surprisingly close 52-40, with many Democrats objecting to Dickson's role in a whistleblower case involving a Delta pilot.

Dickson's family remained behind in the South after he moved to Washington.

"After sometimes long and unavoidable periods of separation from my loved ones during the pandemic, it is time to devote my full time and attention to them," Dickson told FAA staff Wednesday. He said leading the FAA was "the privilege of a lifetime."