Modernizing Air Traffic Management: An Example of Future En Route Operations

By Scott H. Mills

The Federal Aviation Administration's (FAA) current air traffic management (ATM) system has an enviable safety record and accommodates approximately 50,000 flights a day. The expected increases in air traffic volume and complexity, combined with projected budget constraints over the coming years, will create challenges for our nation's ATM system. The safety, capacity, and productivity of the National Airspace System (NAS) can be significantly improved through the integration of enhanced ground and air automation technologies and procedures, as described in the FAA's Operational Evolution Partnership (OEP).

In partnership with the FAA, MITRE developed an end-to-end cross-domain operational concept describing a subset of the OEP capabilities, known as Performance-Based ATM (P-ATM). This concept introduces fundamental shifts in the use of automation capabilities across the NAS that increase operational productivity while still maintaining a humancentered operation. This shift is based on a cross-domain set of capabilities, procedures, and concepts that will revolutionize the way the FAA operates its air traffic system.

Fundamental Changes in the System

Under the P-ATM concept, many routine air traffic control tasks are automated or otherwise made more efficient. Terminal operations leverage a network of highly precise Area Navigation/ Required Navigation Performance routes that are designed to increase flexibility, efficiency, and capacity. The flight deck automation enables aircraft to fly these routes and altitude profiles precisely while exchanging flight status and intent information with the ground system. In en route operations (the focus of the remainder of this article), responsibility for conflict prediction migrates from controllers to ground automation, and controllers resolve conflicts using automated resolution assistance.

Many aircraft are equipped with new or upgraded technologies to generate and transmit precise information about position and intended course to the ATM system on a more frequent basis, thereby ensuring the accuracy of the aircraft's trajectory in the ground system. These aircraft are equipped with air/ground data communications that can be used to send requests for and receive clearances from air traffic control (ATC) that can provide more efficient maneuvers. The management of traffic flows across the NAS is improved under the PATM concept with capabilities that support enhanced decision-making and efficient execution of flight-specific traffic flow initiatives.

The Changing Role of the En Route Controller

En route ATC facilities control aircraft as they move between airport areas. (The areas immediately around airports are referred to as terminal airspace.) In today's environment, en route airspace is divided into sectors, with each sector typically being managed by one or two controllers. These controllers use a radar data display to monitor the progress of aircraft moving through the sector. The controllers are responsible for foreseeing any possible conflicts between aircraft and resolving them by issuing radio instructions for one or both aircraft to change course, speed, or altitude. This is known as ensuring required separation between aircraft so that aircraft are kept at safe distances from each other.

With the P-ATM concept for en route operations, the role of the human air traffic controller is fundamentally changed. For many sectors of airspace, the automation will be responsible for detecting possible conflicts and suggesting resolutions for them. With controller approval, these resolutions will then be transmitted electronically to the aircraft via data communications instead of being transmitted verbally as is done today.

This communication method is efficient because the automation can issue complex instructions directly to the aircraft's flight management computer. It also has the added benefit of eliminating the chance of misunderstanding a verbal instruction issued on the radio. This change in roles will allow each controller to control more air traffic and to focus on long-term strategies for efficient sector operation rather than on individual aircraft conflicts.

Assessing Operational Suitability and Measuring Benefits

In order to make decisions about modernizing the ATM system, the FAA needs to be able to estimate the productivity benefits. As part of this effort, the FAA and MITRE are validating the P-ATM concept through human-in-the-loop laboratory experiments. FAA en route and terminal front line managers (air traffic controllers in management positions) from across the country have participated in assessing both the quantitative benefits and the operational feasibility of this concept.

The FAA front line managers were able to control substantially more traffic in the enhanced automation condition and reported much lower workload.

For the en route environment, the P-ATM concept includes enhanced capabilities such as automated conflict detection, automated conflict resolution assistance, and air-to-ground data communications. A series of discussions and laboratory experiments were conducted to evaluate aspects of the P-ATM concept for the en route ATC environment.

In Experiment One, a baseline condition representing today's ATC system was compared to an enhanced automation (EA) condition, representing a future sector with P-ATM capabilities. The FAA front line managers were able to control substantially more traffic in the EA condition and reported much lower workload. The operational acceptability of the EA environment was rated as very high.

In Experiment Two, the front line managers conducted operations in an EA environment with the added elements of data communication failures and severe weather events that affected aircraft routing. Operations in these conditions also resulted in ratings of very low workload and high acceptability.

In Experiment Three, managers directed traffic through a mixed performance airspace environment employing varying levels of data communication equipage. Results showed high operational acceptability and demonstrated that a greater number of aircraft could be controlled without raising workload levels as equipage levels increased.

Upon completion of the experiment set, the front line managers indicated that they found the PATM concept to be operationally feasible. Experiment results also indicated that traffic management productivity increased significantly when operating in the P-ATM environment, enabling participants to control more air traffic and to manage it more efficiently than in today's ATM environment.

One area of concern for the en route front line manager participants was the change in the controller's situational awareness when operating in the future environment. Because the automation will be responsible for detecting aircraft conflicts, the picture of the overall traffic environment will change significantly for the controller—most individual aircraft will no longer need to be monitored, creating a potentially broader awareness perspective. The implications of this fundamental change in operating methods will be explored in future research on the concept.

Moving Forward

MITRE will continue to work with the FAA to refine operational concepts, analyze areas of concern, and develop operationally acceptable resolutions. This information will be factored into the FAA's air traffic management evolution plan and the development of operational requirements. These requirements will feed evolutionary automation and procedural changes to provide more efficient and effective services to airspace users.

For more information, please contact Scott Mills using the employee directory.

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