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."
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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.
But NPR spoke to three aviation safety experts about the impacts of a potential arch. Their consensus: While the arch itself most likely would not pose a significant risk to most aircraft, it adds yet another variable to a notoriously crowded and complicated airspace.
"It's a small airport with one runway, nestled in a metropolitan area that's surrounded by prohibited airspace [near the White House and U.S. Capitol]," said Jeff Guzzetti, a retired accident investigator with the National Transportation Safety Board and the Federal Aviation Administration.
The congestion — and complexity — of D.C.'s airspace is a well-documented concern, especially after the January 2025 midair collision between an American Airlines regional jet and an Army Black Hawk helicopter that killed 67 people. Even so, some experts worry the FAA may be facing political pressure from Trump to rubber-stamp the project.
"The best, and the most basic option, is simply not to build it," Guzzetti said of the arch.
Shawn Pruchnicki, a former airline pilot and accident investigator who now teaches aviation safety at Ohio State University, went even further. He said putting a 250-foot arch in Memorial Circle would be "inherently dangerous."
"This is an unbelievably ridiculous idea, to put this arch so close to this airport just for the sake of his personal needs," Pruchnicki added, referring to Trump.
The president originally said the arch was for himself, though he has since characterized it as a tribute to the country's 250th anniversary. The White House has repeatedly said in statements that it will be "one of the most iconic landmarks not only in Washington, D.C., but throughout the world," and did not respond to NPR's questions about experts' concerns.
Critics of the arch, of which there are many, have a wide range of objections, from its impact on Arlington National Cemetery and disruption of nearby historic sites to questions about its scale, purpose and financial cost.
Beyer, the Virginia congressman, said he has yet to meet a constituent from his district — on either side of the aisle — who wants to see it built.
"The imminent concern, beyond his narcissism … is what it will do to transportation," he said, referring to planes as well as cars.
The Trump administration said earlier this month it would soon begin preliminary excavation work at Memorial Circle, even though questions — about aviation safety and much more — remain unanswered.
The arch has not yet been approved by a key federal planning commission. Historic preservation experts say the review process has been rushed. And an ongoing lawsuit asserts that the structure can't be built without Congressional authorization, which Trump denies and has not sought. The White House told NPR it continues "seeking final approval from all applicable entities."
What makes D.C. airspace so complicated
Guzzetti said D.C.'s airport, which opened in 1941, was "never meant … to have this amount of traffic."
Because DCA is owned by the federal government, Congress regulates the number of flights — and lawmakers have historically wanted to facilitate travel to and from their home districts. The airport was designed to accommodate about 15 million passengers a year, but now serves closer to 25 million.
Tom Lintner, who spent 30 years working in aviation safety at the FAA — including as an air traffic controller at New York's LaGuardia Airport — said higher traffic density means a smaller margin of error for air traffic controllers.
"As the traffic gets denser and denser, you may find controllers having to make transmissions every five, six, seven seconds," he said. "There reaches a point where there aren't enough seconds left to make the right decision."
The January 2025 midair collision shed light on a pattern of close calls at DCA, resulting in a slew of rule changes and restrictions on helicopters. But some say those measures are not enough.
Just last week, two Democratic senators from Virginia introduced a bill that would cap hourly arrivals and gradually reduce flights over a four-year window starting in 2028. They cited an "overburdened runway" and "unsustainable traffic levels."
"Since the collision, there have been numerous near misses in DCA airspace," Sen. Mark Warner, a co-sponsor of the bill, said in a statement.
Most recently, in early August, a military helicopter carrying President Trump briefly flew too close to a passenger jet leaving DCA. Federal investigators later found that ongoing construction of the White House ballroom contributed to radio problems that prevented air traffic controllers from hearing a warning of the president's takeoff.
Guzzetti says the August incident exemplifies the unique challenges and variables of D.C.'s airspace — even without a 250-foot arch along the primary flight path.
"This is just adding another hazard," Guzzetti said. "Granted, it might not be significant, but still, it's yet another … opportunity for exposure to something bad happening."
How close would planes get?
Guzzetti, like the other experts NPR interviewed, is most concerned about the challenge the arch could pose to planes that are landing, not taking off.
He says the approach to Runway 19 — known as the "River Visual" — is already difficult: Pilots must follow the Potomac River and then make a sharp turn (as abrupt as 40 degrees) at low altitude (less than 500 feet) to avoid prohibited airspace.
"Let's say you pass the area where the arch is going to be. You're probably 60 seconds from touching down on landing," Guzzetti explained. "And then … you've got to make a pretty steep turn to the final approach to get lined up for the runway."
Because of that difficulty, experts said, some airlines require special training to land at DCA or have even designated it as "captain-only," meaning only the more senior officer can do it. They stressed that pilots have to be vigilant and must be able to physically see the river in order to land — which means they would also have eyes on the arch.
"That arch is going to be just a few hundred yards, maybe two or three football fields to the right of where your flight path is," Guzzetti said. "So it's going to look imposing. It's going to be dramatic. But a pilot is not going to mistake that or get too close to it."
The greater risk, experts agree, is in the unknowns.
Lintner is most concerned about helicopters, since they fly lower than planes. He said helicopters operate below 500 feet in some areas, and as low as 200 feet in others — lower than the arch.
Lintner did what he calls "back of the envelope" math, which he outlined in a Substack post in August. Altitude-wise, he said the arch is unlikely to present a problem for airlines. But he said it could further complicate the airspace for helicopters, which he called "the last thing this area needs."
Pruchnicki, of Ohio State, says the Runway 19 approach — which he flew many times as a pilot — is even trickier when it's dark or windy out. He worries that a plane inadvertently flying lower than it's supposed to be, facing strong easterly winds, "could easily get blown into" an arch.
"If everything is working perfectly, I don't see that it would be a significant problem," he added. "However, we all know, at all airports, things go wrong all the time."
Pruchnicki said complications arise all the time in the tricky airspace near DCA, and questioned why the administration would want to build something that could "potentially put passengers' lives at risk" in those moments.
"Why would the White House and the secretary of transportation ever think that is a good idea?" he added. "Who is more important here? The public, perhaps?"
'Nobody's watching the watchers'
The FAA's ongoing aeronautical study is supposed to determine whether the arch would have an adverse effect on the national airspace.
But some aviation experts — and one Democratic lawmaker — worry the agency might be under pressure to greenlight the administration's own project. (The FAA did not respond to NPR's questions about this.)
Part of that is the way the system is set up, Lintner says: The FAA is responsible for operating the U.S. air traffic control system and, at the same time, regulating aviation safety. Critics say this dynamic is unique compared to other countries and ripe for conflict of interest.
"Nobody's watching the watchers," Lintner said. "In other words, anybody who says, 'Wait a minute, how do we know that's safe?' The answer is, 'Well, the FAA decided it's safe.' But did they? What's the checks and balances?"
Under federal regulations, the FAA must be notified before construction of any proposed structure — building, cell tower, crane — that would stand either over 200 feet tall or within a certain slope of airport runways. The agency conducts what is known as an aeronautical study, to determine whether the object would constitute a hazard.
"They'll actually put out a memorandum to indicate: 'Yes, this is a hazard and it needs these types of lights' … or 'It's no hazard, you can go ahead and build it,'" Guzzetti said.
At that point, the entity behind the proposed construction — in the case of the 250-foot arch, the National Parks Service — has 60 days to either agree to those conditions, terminate the study or request further study.
"Further study includes opportunities to negotiate or propose mitigations, and the FAA may request public comment," an informational FAA video explains.
An FAA spokesperson confirmed to NPR that the public comment period for the arch ended on Sept. 3. The rest of the timeline is unclear: Pruchnicki says he's generally seen this process take anywhere from several months to nearly a year.
Depending on its findings, the FAA could ultimately issue a "determination of hazard." But since the agency doesn't have land-use authority, its conclusion is not legally binding.
"The president can simply instruct his [transportation secretary] to write a waiver for that, to ignore that," Guzzetti said. "I can see that happening with this president."
He's not alone. Sen. Tammy Duckworth, D-Ill., wrote a public letter to the FAA in June, urging the agency to "be firm in rejecting any improper or irresponsible pressure from President Trump to prioritize the construction of his gaudy, vanity arch over the safety of the American people."
The White House did not respond to NPR's questions about perceived political pressure.
Either way, Guzzetti said, the FAA would ideally make sure certain steps are taken, such as adding red lights to the arch, clearly labeling the structure on aeronautical charts and monitoring any complaints from pilots and the public about planes getting too close.
"We all know that aviation involves risks any time you defy gravity," Guzzetti said. "But it's managing that risk which is the trick."
Few bodies have approval power over the arch. The National Capital Planning Commission, which has granted some preliminary green lights, is poised to consider it for final approval in the coming months.
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