Visual Assistance for Merging Operations: Effects on Controllers’ Performance, Situation Awareness, and Mental Workload

In future air traffic management, aircraft with modern equipment will approach airports autonomously along optimized trajectories with a minimum of fuel consumption and noise emission (“Continuous descent approaches”, CDAs). Still, the majority of today’s aircraft fleet does not have the equipment to fly CDAs and is directed by the air traffic controller. Thus, there will be a transitional phase in which two traffic streams will approach the airport that have to be merged before landing. In this study we investigated different types of visual aids to support the air traffic controller when preparing the merging of both aircraft types. Specifically, we investigated two types of visual assistance for a better anticipation of the merging situation: ghosting and targeting. While ghosts are projections of the autonomously approaching aircraft onto the arrival route of the actively controlled aircraft, targets indicate where the air traffic controller should position the aircraft under his control to avoid merging conflicts. We examined the effects of several variants of ghosting and targeting on safety, visual attention, resultant situation awareness, and workload with N = 78 undergraduate students in a complex and dynamic microworld setting. While all types of visual assistance had the intended positive effect on merging safety, visual attention for real aircraft was diminished when working with visual aids. Yet, conflict detection rates did not decrease when working with manually activated ghosting system or with targeting. Moreover, anticipation of future conflicts was improved by visual aids. No effects of visual assistance on workload were found. Visual aids are indispensable to accomplish late merging operations safely, although controllers have to be involved actively to avoid losses of situation awareness. The results will inform the design process of assistance systems and procedures.