Air traffic controller performance and workload under mature free flight: Conflict detection and resolution of aircraft self-separation

The effects of conflict detection and self-separating aircraft resolution o n the mental workload and performance of en-route air traffic controllers w ere examined. An air traffic control simulator was used to manipulate traff ic loads and traffic complexity. A mature stage of free flight was simulate d by having controllers monitor self-separating aircraft. Four 30-min scena rios were created to combine moderate (11 aircraft) and heavy traffic loads (17 aircraft) in a 50-mile radius sector with the presence or absence of s elf-separating and conflicting aircraft. Conflicts (defined as a loss of se paration of 5 nm laterally and 1,000 ft vertically) were indicated to the c ontroller by the appearance of a red circle around each of the aircraft inv oked. A self-separation event was defined as an evasive maneuver (either al titude or speed change) made by 1 aircraft to avoid a potential conflict wi th another aircraft. Performance and workload measurements indicated that c ontrollers had difficulty both in detecting conflicts and in recognizing se lf-separating events in a timely manner in saturated airspace. Controller m ental workload also increased, as indexed both by subjective and secondary task measures. Implications for the design of automated tools to support co ntrollers under free flight environments are discussed.