On Target

Teri Bristol explains how airport surface management in the United States is moving into the twenty-first century

The US Federal Aviation Administration (FAA) is on the verge of implementing an exciting new programme – Terminal Flight Data Manager (TFDM). After several years of planning and development, this tower-based Next Generation Air Transportation System (NextGen) programme will improve surface management and efficiency. This automation platform provides new services that replace manually intensive operations in the National Airspace System (NAS). TFDM has three main goals:

  • modernise air traffic control tower equipment by improving electronic flight data exchange and implementing electronic flight strips in the tower;
  • streamline the flow of departures on the surface, saving fuel and reducing carbon dioxide emissions;
  • optimise the experience for the flying public, air traffic control and the airline industry by improving the collaboration and decision-making capabilities between the gate and the tower.

The benefits of TFDM extend far beyond the tower cab. Improved collaboration on the ground will lead to shorter and better-managed queues for take-off. Even modest improvements in queue length management show a significant reduction in fuel burn – decreasing costs for flight operators and reducing environmental impact. Shorter takeoff queues will also improve the experience for the flying public, who will spend less time waiting to take-off.

For instance, Hartsfield-Jackson Atlanta International Airport, one of the busiest airports in the world, experienced more than 34,000 hours of departure taxi delays in Fiscal Year 2018. Modeling shows that TFDM’s surface metering capability will reduce those delays as much as a third, without triggering negative impacts to scheduled departure runway times, gate availability, or arrival traffic.

TFDM implementation, scheduled between 2020 and 2028, will modernise the tower cabs of 93 FAA air traffic control towers at 89 airports. Twenty-seven of those airports are also scheduled to receive the surface metering functionality.

Map of TFDM Deployment. Configuration A sites will receive EFS and Surface Metering; Configuration B sites only EFS.

Electronic Flight Strips and Flight Data Exchange

TFDM will provide improved Electronic Flight Data (EFD) exchange and one of the most significant changes in the tower cab in decades – Electronic Flight Strips (EFS), which will replace the paper flight strips that air traffic controllers use to track the progress of flights. TFDM shares electronic data among controllers through the use of EFS. Updates to routes and overhead flow times will automatically appear on their monitors.

TFDM also shares electronic data among controllers, air traffic managers, aircraft operators and airports, enabling stakeholders to more efficiently stage arrivals and departures and manage surface traffic flow. Stakeholders will have a shared awareness of flights on the ground, the ability to exchange data electronically, a constantly updated picture of traffic volume and more accurate predictive modeling tools to make flights more efficient.

Flight operators will provide new data elements about each flight via the System Wide Information Management (SWIM) network that will allow air traffic control to receive real-time updates of any changes to a flight’s status.

The technology will also interface with a number of other tools to make this coordination possible, including Airport Surveillance Detection Equipment – Model X, Standard Terminal Automation Replacement System, Traffic Flow Management System and Time Based Flow Management and the Flight Data Input/Output system.

This integration will enable departures to hit their spots in the overhead stream and allow controllers and operators to adjust a flight’s pushback time to accommodate. At the Air Traffic Control System Command Center in Virginia, as well as all en route centres and terminal radar approach control facilities across our airspace, we’ll be able to look at surface flow in Atlanta or Chicago and use that improved information to make decisions. EFS makes it easier for controllers to handle fluctuations in traffic volume, changing weather and situations that affect surface traffic decisions such as closed runways.

The first electronic flight strips are scheduled for initial operating capability at Phoenix Sky Harbor Airport in May 2020.

Illustration of Electronic Flight Strip

Enhanced Surface Collaboration

One of the new data elements flight operators will submit with TFDM is the Earliest Off-Block Time (EOBT). Providing and updating an accurate EOBT is pivotal to the successful coordination of traffic on the ground, and in particular for implementing surface metering, as it acts as a first step for each flight’s movement and is the basis for surface metering.

Surface metering or managing a virtual runway queue in a holistic way to decrease congestion while planes are on the ground, requires significant coordination among flight operators and the FAA control tower as well as other stakeholders. To combat increasing taxi-times and congestion at airports across the NAS, surface metering concepts were initially proposed in the late 1990s by the Collaborative Decision Making (CDM) organisation, a partnership between industry and the FAA. In 2012, CDM developed the Surface Collaborative Decision Making Concept of Operations, which provided a guide for the development of the surface metering functionality within TFDM.

Surface metering uses small changes in departure times to alleviate congestion without causing delays. The goal is not just to transfer queued aircraft from a taxiway to another holding area but to reduce taxi times overall by having planes wait at the gate or another non-movement area with their engines turned off. It also operates under the precept of ‘do no harm’, ensuring that arriving aircraft do not incur delays as a result of the surface metering for departures.

How Surface Metering Will Work Within TFDM

TFDM’s scheduler will constantly review projected traffic for potential congestion based on EOBTs provided by the flight operators. When the projected demand exceeds capacity, TFDM will recommend a surface metering program to the traffic manager in the FAA tower for the period of time it projects the capacity imbalance to occur.

Once a surface metering programme is enacted, TFDM will begin issuing Target Movement Area entry Times, or TMATs via SWIM. Every flight scheduled to depart while a programme is running will receive a TMAT. Some of those flights may receive a TMAT that would put them in the movement area slightly later than they would have if they departed without surface metering.

A flight abiding by its assigned TMAT may hold at the gate or stay in the ramp area for a few minutes. However, the system is designed not to impact any flight’s ‘wheel’s off’ time. Any time spent holding at the gate or in the ramp area is time the aircraft is not sitting in a queue on a taxiway.

Each airport will determine their own parameters for programmes such as queue length and under which conditions a surface metering programme would be initiated. Stakeholders at these sites will participate in setting those parameters.

To assist local coordination and to prepare sites and flight operators for implementation, the FAA has formed a Collaborative Site Implementation Team to act as a liaison between the TFDM programme office and external stakeholders. The team’s tasks include running orientations for airports and flight operators on how TDFM works, providing reference materials to guide local stakeholders in setting local parameters, and solving challenges in submitting new data elements.

Development version of TFDM Surface Metering technology

Surface Metering in Action – Learning from a Prototype Programme

The benefits of surface metering are not just theoretical. The National Aeronautics and Space Administration (NASA), in collaboration with the FAA, is running the Airspace Demonstration Technology 2 (ATD-2) prototype programme demonstrating the TFDM concept of operations. ATD-2 is being rolled out in three phases.

The first baseline phase began in September 2017, in cooperation with American Airlines at Charlotte Douglas International Airport in North Carolina. NASA and American Airlines began running surface metering during one of the nine departure banks of flights per day and have now increased to eight of the nine departure banks. Of those flights subject to metering, only 10-17 per cent of flights experienced a metering time constraint and then for an average of only 6.1 minutes.

Even with slight adjustments as those made during ATD-2, the benefits are promising – in efficiency and in environmental and financial savings. Since implementation in Charlotte, surface metering with ATD-2 has saved more than a million pounds of fuel and approximately 2.3 million pounds of carbon dioxide, which is the equivalent of planting almost 38,000 urban trees.

The second and third phases of ATD-2 bring us closer to gate-to-gate efficiency by extending the surface departure metering time horizon with strategic planning tools. The second phase demonstrated interfacing with tower controller electronic flight strips and prescheduling overhead stream insertion into Atlanta Air Route Traffic Control Center. As of April 2019, this phase has also shown substantial benefits, preventing nearly 250 hours of delay by electronically renegotiating a better overhead stream time for almost 2,000 flights. These improvements are in addition to those already gained through surface metering.

The final phase demonstrates a Terminal Departure Scheduling capability that considers multiple airports and terminal boundary constraints. This phase is underway at Dallas/Fort Worth Terminal Radar Approach Control, Fort Worth Air Route Traffic Control Center, Dallas/Fort Worth (DFW) and Dallas Love Field (DAL) Air Traffic Control Towers, and American and Southwest Airlines facilities at DFW and DAL, respectively. We’re excited to see the results as the demonstration evolves.

Beyond TFDM Implementation

Full TFDM implementation across 89 planned airports and 93 towers is a keystone in creating even greater efficiency for the NAS. By integrating TFDM with our other programmes, Time Based Flow Management and Traffic Flow Management System, the FAA, working with flight operators and airports, can actively manage a flight’s performance from gate to gate. Coupled with advances like improved situational awareness through Automatic Dependent Surveillance–Broadcast and streamlined communication between pilots and controllers with Data Communications, TFDM implementation is another pivotal step toward fully realising the goal of NextGen modernisation. As NASA and the FAA have shown with ATD-2, it is our goal to use these tools to create efficiency at every stage of a flight and share those benefits across the aviation community and with the flying public.

A full description of TFDM including a full implementation calendar is available here.

Teri Bristol is chief operating officer of the FAA Air Traffic Organization