In Plane Sight

Scattered across the US, there are more than 150 aging air traffic control towers that regions, municipalities and cities must maintain and eventually, replace.

Constructing a new, brick-and-mortar air traffic control tower can be costly, ranging from $8 million for a small facility to up to $112 million for a large tower like the one under construction at North Carolina’s Charlotte Douglas International Airport. The cost of another new tower, at Philadelphia International Airport, was projected to be $200 million.

Raytheon has partnered with Columbia, Maryland-based  Frequentis USA to develop an alternative to replacing the air traffic control towers at airports. It’s called a Remote Virtual Tower, or RVT. It’s less costly to deploy and maintain, and offers added safety features. Depending on the scale of the airport, an RVT system can cost between $2 to $3 million. Raytheon is seeking an airport to install its first RVT system sometime next year.

“The (Federal Aviation Administration and US Department of Defense) have more than 500 towers that they’ll need to keep up-to-date with the National Airspace System modernization efforts, and then there’s another 20,000 airports and landing strips that don’t even have towers — small, untowered airfields from which weekend pilots fly their Cessnas,” says Chris Rogers, Raytheon Remote Virtual Tower programme manager.

The RVTs allow air traffic controllers to perform all the typical control tower operations, like directing takeoffs, landings and ground traffic, from an office building either at the airfield or miles away. Mounted on masts or existing infrastructure, arrays of cameras, including infrared and pan-zoom-tilt cameras, show controllers what’s happening on the airfield through high-definition video displays. They get a view that is similar to looking out a tower cab’s windows and is customizable to 180, 270 or 360 degrees.

“These airports, airfields and towers don’t look the same physically, and they’re located in different environments,” Rogers says. “But the system is modular, and we can scale and adapt it to suit a particular airport.”

A key component of the remote virtual towers is Raytheon’s Standard Terminal Automation Replacement System, or STARS, which provides air traffic controllers with altitude, position and speed of aircraft descending to and ascending from airports.

“STARS is at more than 600 locations across the US; it’s the main system that air traffic controllers use to guide pilots on takeoff and landings,” Rogers says. “Using radars and sensors, it displays that information on the glass to give the controllers a common picture of the airspace.”

STARS is used in the terminal airspace, which is typically within 60 miles of the airport and 14,000 feet in the air.

“The one shortcoming with observing the airfield on a bank of video monitors instead of looking out a window with your own two eyes is that you lack depth perception,” Rogers says. “STARS will provide situational awareness, helping the controller visualize the air traffic beyond the immediate vicinity of airport and providing tools to ensure safety to the ground.”

By combining Raytheon STARS with a Remote Virtual Tower system, the system can create custom overlays of aircraft information onto the tower display.

“You could show the aircraft identification, beacon code and altitude, among other parameters, and can be customized to specific airports and controllers,” Rogers says. “This is a big advantage to controllers because it reduces their need to view multiple displays. It’s all there right in front of them.”

The Raytheon-Frequentis RVT system can use existing airfield radars and sensors, because STARS can fuse data from multiple sources. For airports without radar coverage, there’s Raytheon’s Skyler low-power radar. Skyler uses active electronically scanned array technology that produces a high-quality picture of low-altitude flights of smaller aircraft and drones, while supporting higher-altitude air traffic and weather.

With the traffic expected if Uber realises its plan to roll out air taxis in 2023, Rogers believes there’s an opportunity to place remote virtual towers to a sizeable portion of the 20,000 or so airstrips without towers.

“I think a ‘Jetsons’ scenario, in which you can take off and land wherever you want, is a leap,” he says. “I think that in the near future of air taxis, it’s going to be more of a point-to-point experience, and remote virtual towers combined with STARS will support efficient and safe air taxi services.”

After the planned first installation in 2020, “we could roll them out across the country, going from one site to the next,” Rogers says. “It will take many, many years, but we’ve got to start with that first one.”

Read Raytheon, Frequentis team on US digital tower technology