At a busy airport, every aircraft in the area shares just a handful of radio frequencies. Spectrum and time are constrained and if multiple people speak at once, both messages can get lost. Communications like “clearance delivery,” which require long transmissions and readbacks, are challenging in high-traffic areas, particularly when weather or other factors require many aircraft to communicate with controllers at once. Going digital clears that channel for urgent, time-critical calls, among other things. And it’s the current practice at some airports, where pilots can confirm clearances with the touch of a button, that the response goes directly to the controller’s screen, and the updated information loads into their flight management system.
Will Cummings-Grande, aerospace engineer with the Systems Analysis and Concepts Directorate based at NASA’s Langley Research Center, is leading technical work that centers around Communications Architecture and Performance for Digital Clearance in NASA’s Air Traffic Management and Safety (ATMS) project. He’s researching the next layer of digital clearance, extending that same logic down to taxi instructions on the ground, so that pushback timing, routing, and runway assignments could also arrive digitally rather than over the radio.
He sought out the most current, ground-level knowledge about how digital clearance delivery works in practice — not in a research paper, but in a real tower, on real systems, with the people who run them every day. The Federal Aviation Administration (FAA) offers the training he wanted to air traffic controllers, so he reached out to the FAA Academy “on a hope and a prayer” that they might accept him as a student.
And in early April, Cummings-Grande traveled to the Mike Monroney Aeronautical Center (MMAC) in Oklahoma City to complete the Tower Data Link Services (TDLS) Application Specialist training — the same two-day, hands-on course required of working controllers at the 72 U.S. airports currently equipped with digital clearance delivery capability.
In the Classroom
Cumming-Grande shadowed a working controller during exercises, trading off at the terminal during breaks so both got time on the system. His classmates were application specialists from Seattle, Sacramento, San Jose, and Fort Lauderdale, all controllers with day jobs managing high-traffic airspace who were there to become the designated system maintainers at their home airports. During breaks, Cummings-Grande had a luxury: time to test. “I got to bounce some of my ideas and concepts off of controllers who are out there interacting with the TDLS and all of the tools it touches in the current system,” he said. “It was great to have both — here’s what the controller-in-training gets, and here’s what I get as a researcher — kind of lumped into the same experience.”
The FAA Academy also connected him with the systems engineers responsible for developing, testing, and implementing new TDLS hardware and software versions, and arranged a visit to the OKC tower to observe the system in live operation.
What He Found
The TDLS runs on fully air-gapped software, completely isolated from standard operating systems — a deliberate cybersecurity design that made the hands-on experience revelatory in ways a research paper couldn’t replicate. “Interacting with the system was just very eye-opening as to how different these systems are from other computers that we commonly interact with,” he said.
The more significant discovery came from the curriculum itself. Reviewing the FAA’s system architecture during training, Cummings-Grande noticed something he didn’t know to look for: a link between the TDLS and the Terminal Flight Data Manager (TFDM), which does not yet exist operationally. That gap is now the center of his research questions. “I didn’t realize I was missing this piece until I took this course,” he said.
Building on Two Decades of Homework
The research Cummings-Grande is pursuing connects to a long thread of NASA work on surface safety and digital communications, including the Terminal Area Productivity program, the Surface Operation Automation Research (SOAR) project, the Low Visibility Landing and Surface Operations (LVLASO) project, and Surface Trajectory Based Operations (STBO) studies. These efforts kicked off in the mid-90s to inform FAA NextGen and demonstrated digital taxi clearances in a series of simulations at multiple facilities and ultimately flight tests at the Atlanta Airport. Those findings showed meaningful workload reductions, but the cost-benefit case wasn’t there yet, and the technology wasn’t ready in the fleet or in the facilities.
What’s changed, in Cummings-Grande’s view, is the convergence of new infrastructure investments, including the rollout of systems derived from Airspace Technology Demonstration (ATD-2) technologies like the Spot and Runway Departure Advisor and the Precision Departure Release Capability through the TFDM, with renewed industry interest from a partner on the aircraft side. “We have all this homework that people have been doing for the last 20-30 years,” he said. “Can we take advantage of the renewed interest from FAA and industry to enable this safety-enhancement?”
His timeline estimate for a fully implemented system leans somewhere in the range of five to ten years. And the payoff, he says, will be tangible to anyone who flies. “This means that your flight will be safer than ever, and that your pilots will be focused on the right things during taxi. Instead of relying on pilots to write down their taxi clearance correctly or be familiar with the airport, the airplane will know and can double-check what the pilot is doing.”
A Case for Partnership
Cummings-Grande isn’t aware of another NASA researcher having taken this FAA course, and he thinks the model is worth repeating. He pointed to terminal procedures design (TERPS) as another area where FAA Academy training could benefit researchers working on urban air mobility and small UAS integration. “Anytime someone needs to do a deep dive into one of the systems — understanding the current state of practice, here are the buttons you push to make this happen — I think it’d be great to have an ongoing partnership with the FAA Academy and make that possible.”
The FAA Academy team was, by all accounts, a willing partner.
Cummings-Grande extends his special thanks to the FAA’s Eric Gandrud and Carol Raiford.