A Hierarchical Closed-Loop Simulation Framework for Aircraft Fleet Operations and Maintenance Under Resource Constraints

Aircraft fleet readiness depends on the interaction between mission demand, equipment condition, maintenance capacity, and spare-parts availability. Evaluating these factors separately can obscure how support decisions affect subsequent mission execution. This study develops a hierarchical closed-loop simulation framework for aircraft fleet operations and maintenance under resource constraints. An entity-level, event-driven model links mission execution, subsystem failures and remaining life, maintenance work orders, and spare replenishment. Explicit observation–command–state-update interfaces separate flight dispatch, maintenance triggering, and maintenance execution from physical-state updates, allowing policies to be compared using the same support processes. A computational study of eight same-type aircraft over a 30-day campaign uses 30 replications per scenario to examine resource configurations, maintenance policies, and mission demand. The results distinguish maintenance-bay and spare-parts bottlenecks and show that relieving one constraint can shift pressure to another. Under the tested resources, earlier condition-based maintenance increases maintenance activity and waiting without a conclusive improvement in mission performance. Higher demand increases sortie generation but reduces availability, mission-batch success, and demand fulfillment. The framework supports resource assessment and maintenance-policy comparison while identifying the operational consequences of mismatches between mission requirements and support capacity.