Abstract: The capability to avoid other air traffic is a fundamental component of the layered conflict management system to ensure safe and efficient operations. The evaluation of systems designed to mitigate the risk of midair collisions of manned aircraft is based on large-scale modeling and simulation efforts and a quantitative volume defined as a near midair collision. Six-degree-of-freedom rigid point mass simulations are routinely employed by standards developing organizations when designing these systems. Because midair collisions are difficult to observe in these simulations and are inherently rare events, basing evaluations on near midair collisions enables a more robust statistical analysis. However, a near midair collision and its underlying assumptions for assessing close encounters with manned aircraft do not adequately consider the different characteristics of smaller drone encounters. The primary contribution of this paper is a quantitative criterion to use when simulating two or more smaller drones in sufficiently close proximity that a midair collision might reasonably occur and without any mitigations to reduce the likelihood of a midair collision. The criteria assume a historically motivated upper bound for the collision likelihood. We also demonstrate that the near midair collision analogs can be used to support modeling and simulation activities.