The Requirements and Technical Concepts for Aviation, Inc. (RTCA) has recently proposed a new concept known as “free flight” for guiding the separation of aircraft in the National Airspace System (NAS). “Free flight” in the United States is a Federal Aviation Administration (FAA) strategic goal for system capacity and for Air Traffic Services to improve accessibility, flexibility, and predictability in the national airspace in order to reduce flight times, crew resources, maintenance, and fuel costs. The scenarios in the current experiment were used to explore the farthest out parameters of “free flight” anticipated by RTCA in the year 2025. An evaluation of predicted scenario generation structures associated with “current day” and “free flight” operations under a specific experimental scenario was performed using two integrated human performance modeling tools, Air Manmachine Integration Design and Analysis System (Air MIDAS) and the Integrated Performance Modeling Environment (IPME). In analyses of a common scenario, each tool predicted a different Point of Closest Approach (PCA) distance under “current day” operations (MAir MIDAS = 5.86 nm, MIPME = 16.67 nm) as compared with “free flight” operations (M Air MIDAS = 6.65 nm, MIPME = 4.94 nm). This indicates that differences in the proximity between the aircraft existed between the two software tools as well as the contextually sensitive variables. This provides evidence that more focus needs to be brought to the effects of contextual effects that impact the virtual human operator of the NAS. A validation effort of these contextual findings with human-in-the-loop (HITL) data is anticipated and required prior to drawing any definite conclusions.