NASA's Future Air traffic management Concepts Evaluation Tool (FACET) is a simulation tool to evaluate next generation air traffic management (ATM) systems. FACET has been gaining popularity with ATM researchers in research years due to its well-designed user interface and robust capabilities for simulating the interaction between the National Airspace System (NAS) and new ATM concepts. Since controller task load and performance is a critical aspect of any future ATM concept, we propose to integrate human performance metrics into FACET. Currently, the only representation of human performance in FACET is through calculation of dynamic density, which estimates controller task load at the sector level through regression analysis of subjective controller ratings for current operations. However, the applicability of dynamic density in its current form for predicting controller task load of future ATM operations is unknown. By integrating human performance metrics directly into FACET, preliminary task load implications and predictions of workload-constrained sector capacity of any future ATM concept would be immediately available to researchers. This would be particularly useful to future ATM tradeoff studies and could be used in lieu of subjective controller ratings for preliminary recalibration of dynamic density for future ATM operations.