A Simulating Experience

Between August and September 2005, controllers from O’Hare fast-forwarded to the year 2018, operating a real-time, human-in-the-loop simulation of a new airport layout plan defined by the O’Hare Modernization Program.


Real-time simulation immerses human participants in the operating environment. By including human factors in the analysis of a “future airport,” extremely valuable information can be gathered that is not obtainable through other methods. As a step in the design process, real-time simulation provides huge potential cost benefits and efficiency improvements ­— all without the turn of a shovel.

The OMP initially considered 15 alternatives, ranging from non-airfield development to several proposed airfield configurations.

In evaluating the relative benefits of the three alternatives that survived the initial and secondary screening processes, the City of Chicago and the FAA conducted an unprecedented series of fast-time simulation analyses. The studies provided a basis for the assessment of the operational performance of the three alternatives. One alternative performed best from a “delay and travel time” perspective.

The O’Hare tower’s Air Traffic Working Group developed an operational concept delegating workload to different controllers throughout the tower cab under the proposed ALP. While confident of the concept, validation of workload levels and coordination between controllers was needed to eliminate concerns. Could the expected traffic levels be managed in the real-life environment? What issues or solutions might exist that could not be envisioned using computational methods?

Human-centered objective and subjective data collected in FutureFlight Central provide accurate workload measures that cannot be obtained in a fast-time simulation. In addition, participants can provide valuable feedback based on their observations and experiences from the simulation.

OMP’s Unanswered Questions

The simulation at FFC was designed specifically to answer those human-factors and procedural questions that fast-time methods are not equipped to address. By providing an environment in which the O’Hare controllers could experience the future ALP, they were able to address many important questions, including:

  • How many controllers are required to manage the traffic?
  • How should the movement area and traffic be divided up among the ground controllers?
  • How manageable was the workload at the ground controller positions?
  • What was the impact of the new ALP on the local controller workload?

From the fast-time analysis of the new ALP, it was known that there would be traffic “chokepoints” for both the East- and West-flow cases — that is, intersections on the airfield where multiple streams of traffic came together and, if not properly managed, could lead to gridlock.

How manageable would these chokepoints be, at peak traffic levels, with pilot/controller communications, controller coordination demands, and human factors such as reaction time and “working speed” all affecting the controllers’ ability to move traffic? Could mitigation strategies be developed for these chokepoints, given the taxiway layout defined by the ALP? Were there taxiway modifications that would enhance the operational efficiency of the airport?

And, there were other questions: How effective would standard, or “coded” taxi routes be for the new ALP, and what would be the impact of traffic management initiatives on airport efficiency and controller workload?

The FAA is planning to build a 22-inch high platform in the center of the O’Hare tower for the ground controllers. This elevated, more centralized view will enhance the controllers’ ability to maintain visual contact with their traffic. During the simulation at FFC, a mockup of the platform was built and installed in the tower cab. This allowed controllers to evaluate the effectiveness of the configuration as part of the simulation, before any work began in the tower at O’Hare.

Gearing Up for the Simulation

The OMP real-time simulation represented the largest simulation of its kind ever attempted. A staff of 25 individuals was hired to act as “sim-pilots” for the simulation, and were trained over a period of six weeks to communicate with the controllers and operate the traffic at the “new” O’Hare. The job of the sim-pilots is complex and demanding for busy airports like O’Hare. The success of the simulation is dependent upon the sim-pilots’ ability to work together as a group to manage the high levels of traffic around the airfield, which provides the O’Hare controllers with the look and feel of really “being there.”

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