Airport departure operations are often affected by surface congestion caused by interactions among airline readiness, ground traffic conditions, and runway capacity constraints. To improve departure flow predictability, the Target Start-up Approval Time (TSAT) has been introduced as a key decision variable for regulating pushback timing. This study investigates a runway departure scheduling problem based on a TSAT decision model and proposes a modeling framework using max-plus algebra. The departure process, including pushback, taxiing, runway queuing, and take-off, is represented as a discrete-event system in which synchronization constraints and processing times are explicitly described by max and addition operations. This formulation provides a transparent representation of event-time propagation from pushback to take-off and clarifies the temporal structure underlying airport departure operations. Numerical examples and sensitivity analysis are conducted under a simplified airport scenario inspired by Tokyo International Airport (Haneda). The results show that departure performance is highly sensitive to departure sequencing decisions and wake turbulence separation constraints, and that TSAT primarily influences runway queue formation rather than directly determining take-off order. These findings clarify the operational role of TSAT in structured departure flow management.

Keywords

Airport departure scheduling, Target Start-up Approval Time (TSAT), Max-plus algebra, Discrete-event systems, Runway sequencing.