Information Complexity in Air Traffic Control Displays

Air traffic controllers typically use visual displays to interact with various automation systems. Automation tools are intended to reduce controller task load, but they may also create new tasks associated with acquiring, integrating, and utilizing information from displays. Consequently, the complexity of information displayed may reduce the efficiency and effectiveness of an automation system. Moreover, complexity could cause controllers to miss or misinterpret visual data, thereby reducing safety. Thus, information complexity in air traffic control (ATC) displays represents a potential bottleneck in ATC systems. To evaluate the cost and benefit of an automation system, it is important to understand whether the information it provides is too complex for controllers to process. The purpose of this study was to answer three basic questions: 1) What constitutes information complexity in automation displays? 2) What level of display complexity is " too complex " for controllers? 3) Can we objectively measure information complexity in ATC displays? In this study, we first developed a general framework for measuring information complexity. The framework reduces the concept of complexity into three underlying factors: quantity, variety, and the relations between basic information elements; each factor is evaluated at three generic stages of human information processing: perception, cognition, and action. By this definition, we decompose complexity into a 3x3 matrix, measuring the effects of a complexity factor on information processing at a given stage. We then take the following steps to develop complexity metrics for ATC displays: 1) Identify task requirements of using the displays in ATC; 2) Determine corresponding brain functions pertinent to the task requirements; and 3) Choose the metric that can measure the effects of the complexity factor on the brain functions. Using this approach, we developed nine metrics of ATC display complexity. These metrics provide an objective method to evaluate automation displays for acquisition evaluation and design prototypes.