D.C. airspace is complicated. Experts say Trump's arch would add one more risk

A passenger plane flies over the location of Trump's proposed 250-foot arch on its descent into Ronald Reagan Washington National Airport. Al Drago for The Washington Post via Getty Images hide caption

The Trump administration is eager to press ahead with its proposed 250-foot arch at Memorial Circle, a traffic island on the historic bridge connecting Washington, D.C. to Arlington, Va.

The grassy roundabout is not far from Ronald Reagan Washington National Airport (DCA): An arch would stand just about two aeronautical miles from the airport's main runway, which is one of the busiest in the country .

"An enormous number of airplanes come over that site, basically every 45 to 60 seconds all day long 'til 11 at night," U.S. Rep. Don Beyer, a Democrat who represents that part of Virginia, told NPR. "Just imagine the disaster that could happen with all of these airplanes coming right across a 250-foot-high arch."

The Trump administration maintains the arch would not pose an additional risk.

A preliminary Federal Aviation Administration report said in June that the structure would likely not be an issue as long as it has blinking red obstruction lights on top, as the 555-foot-tall Washington Monument does. But it is still in the process of conducting a more comprehensive study, which could lead it to label the arch "a hazard."

An FAA spokesperson told NPR over email in early September that "the standard obstruction evaluation process is under way," both for the arch and cranes that would be used for construction, which the administration has said could be up to 320 feet tall.

Neither the FAA nor the White House shared a timeline or further details about those reviews.