At a busy airport, each aircraft in the field shares only a few radio frequencies. Spectrum and time are limited and if multiple people speak simultaneously, both messages may be lost. Communications such as “clearance delivery”, which require long transmissions and readbacks, are challenging in high-traffic areas, especially when weather or other factors require multiple aircraft to communicate with controllers. Going digital clears that channel for urgent, time-critical calls, among other things. And this is current practice at some airports, where pilots can confirm clearance with the touch of a button, causing feedback to go straight to the controller’s screen, and the updated information loaded into their flight management system.
Will Cummings-Grande, aerospace engineer in the Systems Analysis and Concepts Directorate at NASA’s Langley Research Center, is leading technical work that focuses on communications architecture and performance for digital clearance in NASA’s Air Traffic Management and Safety (ATMS) project. He is researching the next layer of digital clearance, extending the same logic to taxi instructions on the ground, so that pushback timing, routing and runway assignments can also be reached digitally instead of by radio.
They looked for the latest, ground-level information 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) provides air traffic controllers with the training he wanted, so he arrived at the FAA Academy “on the hope and 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 Tower Data Link Services (TDLS) Application Specialist training – the same two-day, hands-on course that is currently required of controllers working at the 72 U.S. airports equipped with digital clearance delivery capability.
in class
Coming-Grande shadowed a working controller during practice, trading off on the terminal during breaks so both could get time on the system. His classmates were applications specialists from Seattle, Sacramento, San Jose and Fort Lauderdale, all controllers with daily tasks managing high-traffic airspace who had gone there to become designated systems maintainers at their home airports. During the break, Cummings-Grande had one luxury: time to test. “I got to share some of my ideas and concepts with the controllers who are interacting with TDLS and all the devices it touches in the current system,” he said. “It was great to have both – here’s what the controller gets in training, and here’s what I get as a researcher – trapped in the same kind of experience.”
The FAA Academy also connected them with systems engineers responsible for the development, testing, and implementation of new TDLS hardware and software versions, and arranged for a trip to the OKC tower to observe the system in live operation.
What did he find out
TDLS runs on completely air-gapped software, completely isolated from standard operating systems – a deliberate cybersecurity design that made the hands-on experience revelatory in ways that a research paper cannot replicate. “Interacting with the systems was very eye-opening as to how different these systems are from other computers we normally interact with,” he said.
The more important discovery came from the course itself. While reviewing the FAA’s system architecture during training, Cummings-Grande noticed something he did not know to look for: a link between TDLS and the Terminal Flight Data Manager (TFDM), which did not yet exist in operation. That difference is now the focus of their 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 working on connects to NASA’s longstanding work on surface security and digital communications, including the Terminal Area Productivity Program, the Surface Operations Automation Research (SOAR) project, the Low Visibility Landing and Surface Operations (LVLASO) project, and the Surface Trajectory Based Operations (STBO) studies. These efforts to inform FAA NextGen began in the mid-90s and digital taxi clearance was demonstrated in a series of simulations at multiple facilities and ultimately flight tested at the Atlanta airport. Those findings showed meaningful workload reductions, but the cost-benefit case was not yet there, and the technology was not ready in fleets or facilities.
In Cummings-Grande’s view, what has changed is the convergence of new infrastructure investments, including the rollout of systems derived from Airspace Technology Demonstration (ATD-2) technologies, such as Spot and Runway Departure Advisors and Precision Departure Release capability via 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 the FAA and industry to enable this safety-enhancement?”
Their time-frame estimate for a fully implemented system is between five and ten years. And he says that anyone who flies will benefit from it. “This means your flight will be safer than ever, and your pilots will focus on the right things during taxi. Instead of relying on pilots to correctly type their taxi clearance 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 is not aware of any other NASA researchers having taken this FAA course, and she believes the model is worth replicating. He pointed to terminal process design (TERPS) as another area where FAA Academy training could benefit researchers working on urban air mobility and small UAS integration. “Whenever someone needs to go deeper into the system – understanding the current state of practice, here are the buttons you push to do that – I think it would be great to have a continued partnership with the FAA Academy and make that possible.”
The FAA Academy team was, in every sense, a willing partner.
Cummings-Grande extends her special thanks to the FAA’s Eric Gandrud and Carol Raiford.
