Introducing the Next Level in Air Traffic Efficiency

More predictable arrival and departure times for passengers. Lower fuel usage for airlines. Reduced aircraft emissions. 

These are just some of the benefits of an improved air traffic methodology the Federal Aviation Administration (FAA) has begun to introduce in the National Airspace System—with help from MITRE's technical expertise.

The new approach is called Trajectory-Based Operations (TBO). It's based on a flight's predicted path between origin and destination, defined in four dimensions: latitude, longitude, altitude, and time. 

"What's really new about TBO is that each trajectory incorporates not only the expected path an aircraft plans to fly, but also the times at which it will cross specific points along that path," says Elly Smith, who leads MITRE's TBO work.

"That fourth dimension of time provides a common planning reference that allows us to predict where aircraft will be in the future. And that means air traffic managers can stay ahead of problems, such as situations where demand exceeds the capacity of the airport or the airspace."

"TBO isn't just about achieving efficiencies for each individual flight. It's a whole-system approach," adds Paul MacWilliams, who oversees MITRE's laboratory research on TBO. "It's making sure that, as a system, the entire collection of aircraft receives the greatest pool of benefits available." 

And that, he says, depends on all the necessary systems and operating procedures working together. 

Ensuring that systemwide cooperation required many years of research and development. The FAA and MITRE, which operates the FAA's federally funded research and development center, partnered in that effort.

"We worked with the FAA and the aviation community to research, evaluate, design, and validate how the interdependent capabilities should be integrated with each other," MacWilliams explains.

Connecting the Systems that Enable Trajectory-Based Operations

A variety of systems enable TBO, including the sophisticated navigation capabilities onboard aircraft that allow pilots to fly precise point-to-point paths in time and space. They also include numerous FAA systems and decision support tools that enable improved traffic flow management, better information sharing between controllers and pilots, and more extensive data exchange across different air traffic management domains.

TBO begins with the aircraft operator, who files a flight plan and provides other data that automation uses to generate a planned gate-to-gate, four-dimensional (4D) trajectory. The operator may also file several other flight plan options that can be used to generate alternative 4D trajectories to overcome changing system constraints. Air traffic management will then try to accommodate the operator's preferences, keeping in mind overall traffic demand and other system constraints, such as sections of airspace temporarily reserved for special uses like military operations or space launches. Automation will support this process.

"TBO uses new and enhanced systems and technologies to provide a connectivity that didn't exist before. We helped the FAA make those system connections," MacWilliams says.

During flight, controllers will make minor, real-time adjustments to an aircraft's 4D trajectory to ensure that each flight meets its scheduled arrival time at its destination and at various points along the way. Traffic managers and controllers will also make flight trajectory adjustments to address evolving conditions, such as changing winds or weather, unexpected runway conditions, or changes in airport capacity.

"The result is better traffic flow management across the system," Smith says. 

A System that Will Impact the Globe 

The rollout of this new methodology will occur in stages. The first phase is already underway in three National Airspace System operating areas: Denver, Atlanta, and the Northeast Corridor, the heavily trafficked area between Washington, D.C. and Boston. 

To make the shift to TBO as smooth as possible, the FAA and MITRE are engaging with personnel at the facilities participating in the initial rollout to help prepare them for this air traffic management change through education and pre-implementation risk-reduction activities. We're also conducting studies with pilots that simulate different TBO scenarios they may experience to ensure sufficient flight deck operational integration and pilot readiness. 

These efforts will enable not only a smooth initial rollout but also TBO's systemwide implementation.

For now, TBO focuses on traditional airspace users—such as airlines and private pilots. However, it could have a profound effect on the way all forms of aerospace traffic will be managed in the future, from drones flying at low altitudes to rockets traversing the airspace on their way to space.

"As a methodology, TBO has the potential not only to improve the flying experience for millions of people across the globe," Smith says. "It could also be the answer to seamlessly and safely integrating a wide array of operations into the global aerospace in the coming years."

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