New L.A. Stadium May Need Stealthy Design to Evade Airport Radar

  • $1.9 billion Rams venue would interfere with radar, FAA says
  • Proposed home for football team is under approach to airport

Developers of a proposed stadium to house the National Football League’s return to Los Angeles may have to treat the glimmering venue like a stealth bomber.

The $1.9 billion facility planned for the Rams and possibly another team by 2019 could interfere with Los Angeles International Airport’s radar, creating a hazard for aircraft landing at the fourth busiest airstrip in the U.S.

Rendering of new Rams stadium
Rendering of new Rams stadium
Source: HKS Architects

Now the Federal Aviation Administration has declared the structure a hazard to aviation and proposed a variety of possible design changes and fixes. Nobody is saying it needs to resemble the bat-winged, radar-evading B-2 bomber, but designers may need to lower the building’s height or find a way to reduce radio-wave interference.

“You’re trying to do the exact same thing that you do with a stealth airplane,” said John Hansman, an aeronautics and astronautics professor at the Massachusetts Institute of Technology.

Absorbent Coating

That means either coating the structure with materials that absorb the radar’s radio waves instead of reflecting them, or altering the plan’s design so that its structures bounce the signals harmlessly into the ground or skyward, according to Hansman.

The proposed stadium, to be built in Inglewood within 2.5 miles of a runway, would block a swath of the radar’s view and may cause a plane’s location to be plotted miles from where it’s actually flying or make it appear to dart back and forth, according to the FAA report.

“Pending resolution of the issues described below, the structure is presumed to be a hazard to air navigation,” the FAA said in a Nov. 9 notice summarizing its report. That means it is technically being blocked, though the decision isn’t final and builders and the agency are in talks on how to resolve the problem, according to a statement by the FAA.

“Once the negotiation phase starts, there are no specific deadlines for completing it,” the agency said in the statement.

Hollywood Park

The developers of the stadium, Hollywood Park Land Co. LLC of Los Angeles, didn’t comment in response to requests to discuss the project. Inglewood Mayor James Butts said developers and the FAA and are considering removing radar-reflecting aluminum from its roof and adding an absorbing outer coating.

Plans call for the domed stadium to be built on the site of the former Hollywood Park horse racing track, a local institution built in 1938 by entertainment-industry pioneers including Harry and Jack Warner of what is now known as Warner Bros. Entertainment Inc. It would feature wing-like sweeping structures on the side facing west, which face the airport radar.

From the start, the proposal has been controversial. A competing company that had wanted to build a stadium in downtown Los Angeles hired Tom Ridge, former Homeland Security secretary, and Mark Rosenker, who had served as head of the National Transportation Safety Board, to study the Hollywood Park plan. They raised potential security and aviation-safety concerns even though other stadiums have been built near airports.

Radio Beams

At its simplest, radar works by reflecting radio beams off metal objects, such as aircraft. Unfortunately, the metal and some other dense materials used in construction can also reflect these radio waves.

Reflections off the stadium itself won’t be an issue, in part because its surface is covered with small holes that will “disturb” the return signal, according to the FAA.

However, all aircraft above Los Angeles and other busy corridors are required to send out a secondary radio signal -- containing their identification, altitude and other critical data -- each time they sense a radar’s waves have reached them. It is this secondary radar beacon that will cause problems.

The FAA forecast these signals will bounce off the structure, sending confusing “false targets.” Some of them might make it appear that stray aircraft are directly within the final approach path to some airport runways, according to the agency. Such ghost targets would cause havoc for controllers if they appear too frequently.

NextGen System

The aviation agency’s report listed ways to help mitigate the interference and allow the project to move forward, including lowering its height, reshaping its face, and using materials and finishes to lessen radio-wave reflections. Newer technologies, such as the satellite-based tracking the FAA is phasing in as part of its NextGen air-traffic system, may also lessen the severity, according to the agency.

While it may not be feasible to coat the entire new stadium in the latest radar-absorbing materials and solving the issues will be complex, there are proven ways to deal with radar interference, said Kurt Sorensen, manager of a team at Sandia National Laboratories in Albuquerque, New Mexico, that has studied the same issue involving wind turbines.

“I have to believe it’s solvable,” Sorensen said.

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