• Washington currently heads Denver International Airport and previously led public transportation systems in Los Angeles and Denver.
• If confirmed, Washington's challenges will include helping the FAA improve its reputation after its approval of the Boeing's 737 Max, two of which later crashed, killing 346 people.
• The agency is also tasked with reviewing new Boeing planes.
• More recently, the FAA and airlines have pointed fingers over the causes of flight delays.

President Joe Biden on Wednesday nominated Phil Washington, the head of Denver International Airport, to lead the Federal Aviation Administration.

Washington's nomination to run the agency, which has roughly 45,000 employees, comes after Steve Dickson left the post about halfway through his term, at the end of March, citing personal reasons. Billy Nolen, the FAA's safety chief, was named as acting administrator. Washington has headed the Denver airport, one of the country's busiest, for about a year and previously was CEO of the Los Angeles County Metropolitan Transportation Authority for six years.

If confirmed, Washington will head an agency that has been working to improve its reputation after two fatal crashes of Boeing's 737 Max planes, which led to legislation that tightened federal oversight of new jetliners.

The FAA is also tasked with reviewing new Boeing jets like the 777X and the largest model of the Max, the 737 Max 10.  It hasn't yet cleared Boeing to resume deliveries of its Dreamliner planes, which have been paused for more than a year due to manufacturing flaws.

The agency has also been working with airlines to bring down the rate of flight delays and cancellations amid staffing shortages and other challenges. Tensions between the FAA and airline executives have escalated lately as they have blamed each other over an uptick in flight disruptions that has upended the travel plans of thousands of passengers.

Airline executives have called out the staffing of air traffic controllers, which the FAA oversees, as causes for delays.

"The reality is that there are more flights scheduled industrywide than ATC staffing system can handle," United Airlines Chief Operating Officer Jonathan Roitman wrote in a staff note Wednesday, calling out congested parts of New York and Florida. "Until that is resolved, we expect the U.S. aviation system will be challenged this summer and beyond."

The FAA, in response, said that its staffing is not the cause of most of the delays and cancellations, and instead attributed the issues to air traffic control capacity, airline staffing, weather and strong traffic.

United recently trimmed its schedule at Newark, New Jersey, to help avoid delays. Other carriers including Delta, JetBlue and Southwest have also cut flights so they aren't overwhelmed when routine disruptions happen.

In a statement, the FAA said it appreciates the steps airlines are taking to improve performance, but that more clearly needs to be done to reduce cancellations and delays.

"It is unfortunate to see United Airlines conflate weather-related Air Traffic Control measures with ATC staffing issues, which could deceptively imply that a majority of those situations are the result of FAA staffing."