Air Traffic Controller Performance and Workload Under Mature Free Flight: Conflict Detection and Resolution of Aircraft Self-Separation

Abstract

The effects of conflict detection and self-separating aircraft resolution on the mental workload and performance of en-route air traffic controllers were examined. An air traffic control simulator was used to manipulate traffic loads and traffic complexity. A mature stage of free flight was simulated by having controllers monitor self-sepa-rating aircraft. Four 30-min scenarios were created to combine moderate (11 aircraft) and heavy traffic loads (17 aircraft) in a 50-mile radius sector with the presence or ab-sence of self-separating and conflicting aircraft. Conflicts (defined as a loss of separa-tion of 5 nm laterally and 1,000 ft vertically) were indicated to the controller by the ap-pearance of a red circle around each of the aircraft involved. A self-separation event was defined as an evasive maneuver (either altitude or speed change) made by 1 air-craft to avoid a potential conflict with another aircraft. Performance and workload measurements indicated that controllers had difficulty both in detecting conflicts and in recognizing self-separating events in a timely manner in saturated airspace. Con-troller mental workload also increased, as indexed both by subjective and secondary task measures. Implications for the design of automated tools to support controllers under free flight environments are discussed. The rapid growth in worldwide air travel projected for the next decade will dramati-cally increase the demand for air traffic services. This demand will increase loading