Eurocontrol has demonstrated the technical and operational benefits of a new ATC decision aid known as medium-term conflict detection (MTCD), which could also provide cost-efficiency and environmental benefits to boot.

MTCD calculates aircraft trajectories, initially on the basis of flight plans, aircraft performance parameters and meteorological information, refining them subsequently by monitoring the actual performance of the aircraft. It then notifies the planning controller of any pair of aircraft on conflicting flight paths.

Trajectories are modeled with a buffer zone around each aircraft to allow for deviations from the predicted position, so the MTCD tool actually checks for separation loss between buffers. The buffers are sized to reflect the degree of uncertainty. During cruise, accordingly, the vertical uncertainty shrinks to 300 feet while during climb and descent it increases to 1,500 feet. Across-track uncertainty remains constant, but along-track uncertainty grows with time from a relatively small value at takeoff.

A conflict is declared if horizontal separation is predicted to fall below five nautical miles at the same time that vertical separation drops to less than 700 feet. In that case, a potential problem display window on the planner’s traffic display screen shows the time of conflict and predicted minimum separation. A vertical assistance window depicts the vertical profile of the conflicting flights, along with any context aircraft that might have a bearing on how the conflict is resolved. The potential conflict is also highlighted on the tactical controller’s main radar display.

Extended Area of Interest
To accommodate predicted conflicts that could involve aircraft currently outside the sector or that will occur after they have left it, MTCD extends the planning controller’s area of interest outside the vertical and horizontal limits of the ATC sector. The area of interest is defined instead by a time horizon extending beyond the sector’s horizontal limits, and includes factors such as the availability of radar data. The tactical controller’s area of responsibility remains the sector defined by vertical and horizontal limits, but can be extended by delegation or the early release or transfer of flights from adjacent sectors.

On detecting a problem, the planner analyzes it and can decide whether to disregard it, continue to monitor it, take action to resolve it or delegate the task to the tactical controller.

Trials over the last two years at the Malmo and Rome area control centers and Eurocontrol’s own upper-airspace control center at Maastricht found that in upper-airspace sectors MTCD helped early identification and resolution of conflicts. The tool also demonstrated its potential to increase sector productivity and safety by improving task distribution between the planning and tactical or executive controller.

MTCD effectively switches some of the workload to the planning controller from the tactical controller, who handles communications with aircraft and is normally much busier than the planner. The resulting reduction of the demands on the tactical controller could translate into additional capacity. Environmental benefits could come in the form of more direct routings.

Eurocontrol’s MTCD project manager, Chris Brain, expects the tool to become a building block of the future European air traffic management system: “It represents the starting point for the introduction of the next generation of decision-support tools for air traffic controllers.”