Remote air traffic control towers
The technology is ready. FAA is not.
By Dr Mike Jones
Contributing writer
For the past 50 years, the technology deployed in America’s 520 air traffic control towers has ossified. They are still tall buildings with big windows, using analog radios, printing paper flight strips, and shuffling airplanes around the field using the Mark One eyeball.
Each of the component systems in the towers are proprietary systems. They’re often quite old and are not integrated in any way, which increases training, maintenance, and support costs.
These low-tech towers are ferociously expensive. The tower at ATL (Hartsfield-Jackson, Atlanta GA) cost $94 million in 2006. The new tower at AVL (Asheville NC) will cost $55 million. And the new facility at SMF (Intl, Sacramento CA) is budgeted at $60–$80 million. Even towers at small general aviation (GA) airports are pricey at $15–18 million each.
The US Congress approved $25 billion in 2021 for replacement towers. In 2023, FAA published a plan to replace dozens of antiquated control towers.
But the plan did not address the root problem facing FAA – building expensive new towers using old equipment neither advances the capacity or the safety of an airport, while the costs prohibit the deployment of air traffic control (ATC) services to other busy but smaller airports. A better idea which is barely mentioned in that plan is to upgrade the entire airport control system with new digital technologies, usually termed a “remote digital tower.”
Digital and integrated
Digital towers are frequently used in Europe and Asia. They deliver significant upgrades in airport ATC capabilities with capital costs alone saving as much as 90% over the cost of a traditional brick-and-mortar tower.
Four companies have incubated this technology to be operational on a large scale. One of the first was created by Saab, which has operational systems in Sweden and the UK, including the LCY (London City, London UK). Searidge Technology claims to have 35 operational sites in 25 countries.
Another pioneer is Indra, a Spanish technology firm that has a strong foothold at Norwegian airports. And the last major player is Frequentis, an Austrian technology company that has joined forces with RTX (formerly Raytheon), which is deeply embedded and trusted by FAA. Frequentis has invested $100 million of its own funds developing a system which is now undergoing testing at FAA’s facility at ACY (Intl, Atlantic City NJ). If all goes well, it could be certified by the end of 2025.
Austrian engineer Dieter Eier is the tea-drinking president of Frequentis USA. He explains the company’s core competency is centered around massive, integrated, public safety command centers. For example, in the mid 2000s, Frequentis won a contract with Scotland Yard to build control centers in London that would integrate the video from 60,000 security cameras. “Here in the US, we have been supplying voice switches to FAA since 2004. We’re now at more than 200 airports, TRACONS, and ATC centers,” he declares. World-wide, Frequentis books about $500 million in annual revenues.
Frequentis is currently on the third iteration of its remote tower system. Eier reports that the system has integrated 3 rapidly evolving technologies – improvements in cameras, large flat-screen displays, and the availability of fiber optic links. “In the past 10 years, camera technology got incrementally better. “It jumped,” adds Eier. “From 2018, when the Searidge system for Colorado went in, to 2024, when we built our system at FAA’s R&D center, the difference was big. It’s unbelievable.”
The first installation was at the old Homestead Air Force Base (AFB) in Florida. The second was at Moody AFB in Georgia. And the third was in Corpus Christi TX. During each installation, Frequentis learned more about what the technology could do and what controllers actually wanted.
Eier estimates they made 20 upgrades to the software while operating in Florida. “We listened to both the controllers and the results of the evaluation from Miter Corporation,” explains Eier. “By the time we were done, the feedback from the Corpus Christi facility was just overwhelmingly positive.”
How it works
Frequentis’ latest system has a list price of about $4 million. It involves high-resolution visual and thermal cameras mounted on a mast between 40 and 100 ft tall. Eight cameras form the primary system, with 8 additional units that substitute instantly and automatically if a failure is detected. On top of the mast are “pan, tilt, and zoom” (PTZ) cameras which are operated by each controller, giving them the ability to focus on any point of interest.
These cameras can pivot 360˚ in just 4 seconds, and can spot aircraft up to 15 miles distant. Each camera has a lens-cleaning system that ensures the image is never degraded by rain, ice, or dust. Overall, the system collects roughly 22 gigabytes of video and audio data per second and transmits that information via fiber optic links back to the control center, which can be anywhere.
Tim Arnett is the program manager at Frequentis. He has spent 6 years climbing towers and calibrating cameras. “I thought the high-definition video at Moody was wonderful until we saw an airport in 4K,” he says. “Once the controllers in Corpus Christi saw 4K, they said ‘we have to have 4K.’ We listened and learned.”
In the control center, the images are displayed on a panorama of high-resolution flat panel displays arranged in an arc of about 220˚. The video is compressed digitally so that the 360˚ view collected from the cameras fits onto the display in front of the controllers, who sit comfortably at a desk and no longer have to stand or twist to observe traffic from all directions.
Arnett was worried about the “stitching” of the images, and the distortion of compressing a 360˚ field of view onto the 220˚ arc. During the first tests in Florida, Arnett drove his car around the field while one of the controllers was on the phone, monitoring the screens. The controller reported the stitching was perfect, without a blind spot or gaps. When Arnett drove off the edge of the display to the right, he and his car instantly showed up on the left.
“This video technology is really,” notes Eier. He says that merging videos together seamlessly in real time is as much of an art as a coding problem. “You have to project the panorama – the curvature of Earth – onto a flat screen so that it doesn’t look fisheye. The art is making the runway look straight.”
Frequentis Director of Business Development Larry Major concurs with Eier’s opinion on the optical improvements. “I visited the system in Corpus Christi, and the controllers were looking at the 4K screens with binoculars,” he adds. “I thought they were teasing me. But the resolution on the screen is so good that they could actually use binoculars to see airplanes they couldn’t see with their eyes.”
New capabilities
Compared to an ordinary control tower, the Frequentis system offers controllers a variety of enhanced capabilities that a glass-and-steel tower simply can’t match. First and foremost is enhanced situational awareness (SA).
Because the panorama is a giant computer screen, Frequentis is able to insert digital data over the video. The system labels each aircraft, truck, and tug with a computer-generated tag. That tag follows the target even beyond visual range. Paper “flight strips” are obsolete.
The system also self-generates warning symbology around unexpected or unusual objects. For example, a ramp closed for maintenance is tinted red. A restricted area can be highlighted with a box. Tags can be generated for prominent navigational reporting points such as lakes, towers, or hilltops. Runway distance measurements can be posted or removed, as the controller desires. As for wildlife, Eier explains that if an object moves, like a seagull, the system put an alert box around it instantly.
Of course, night is a problem for controllers relying only on their eyes. With the Frequentis system, the controllers simply switch to thermal mode. Airplanes, vehicles, and wildlife can be seen in full detail. This reporter watched a recording of a fox running in front of a pair of Fairchild Republic A-10 Thunderbolt II jets at night. Neither the traditional tower controllers nor the pilots saw the
animal, which could have caused catastrophic damage had it been sucked into an engine.
“One time, they were having a base exercise in the woods where they had some people pretending to attack the base,” recalls Eier. “We watched them on infrared and called base security and were able to report their location precisely. That was a big boost for security.”
Controllers value the versatility of the PTZ cameras. In addition to their ultra-high resolution, these cameras swivel and tilt with incredible speed. “Let’s suppose the controller is looking over at that hangar because there’s something weird going on,” says Eier. “He or she presses a button and the PTZ camera is locked in and follows the target automatically. These are great tools to help controllers do their job better.” The PTZ camera even has a light gun built into the system, allowing red and green signals to be aimed with pin-point accuracy.
The Frequentis system has been built with robust security and the reliability expected from an aeronautical system. The system includes full redundancy on every component, including electrical power and the diverse routing of the fiber optic links. The system latency is measured in milliseconds, and the system has been engineered to operate 10 years between major failures. “You can’t add safety on at the end. You have to design the system and build it with safety already in it,” says Eier.
A reluctant FAA
Remote towers are increasingly popular outside of the US in countries that have privatized their ATC services. Privatized services focus on costs efficiency and employee productivity. Delivering better ATC services to more airports at a lower cost perfectly fits that mantra. This leaves the US behind in the deployment of this new technology.
One country leading in remote towers is Norway, which privatized its ATC services into a company called Avinor. That firm invested about $125 million into a centralized control center in Bodø, Norway, using the Indra system. Currently, 15 airports are controlled from Bodø. By 2026, the number will be 22. For even great efficiencies, the Bodø system allows a single controller to manage up to 3 airports simultaneously.
Frequentis operates 6 remote towers at airports in Germany. PEN (Penang, Malaysia) and JHB (Johor, Malaysia) are both served by a center in distant Kuala Lumpur. Saab has operations in Sweden and has been very successful in Ireland. In a study published in 2018, researcher Wen-Chin Li estimated that the Saab system at Irish airports reduced operating costs by £1.3 million per year, and deemed it “at least as safe” as traditional ATC.
Back in the US, FAA has a poor track record of implementing innovative technology gracefully. It’s a big, lethargic bureaucracy that is risk-averse. Majors notes that in Canada, a team of 2 people test, certify, and procure all the aviation radios that the airports need. At FAA, the same work is done by a group of 60.
Some blame must be placed on the US Congress, which has had difficulty funding multi-year technology projects. It also has burdened FAA with a bewildering array of sometimes conflicting obligations and constraints, making it difficult to operate in a business-like fashion. The slow deployment of cost-saving innovation at FAA has many causes – although few cures.
However, there can be no doubt that these systems are working quite successfully and safely. Adopting this technology would reduce the cost of replacing current towers and stimulate the expansion of air traffic control services to new airports. It would reduce the controller workload and add important new safety features to the controllers’ toolbox. One can only hope that the current emphasis on government efficiency will stir the pot and squeeze a modicum of innovation out of FAA’s lengthy certification process.
Dr Mike Jones is the general aviation associate at the Swelbar-Zhong Consultancy, working with GA airports to facilitate their governance and operations. He also is a writer, a successful entrepreneur, and a commercial pilot with about 4000 hours in his logbook.