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Urban Air Mobility (UAM) is an emerging aviation concept that could supplement today’s ground and air transportation systems. For UAM, it is generally assumed that the private sector will manage separation and not rely on the U.S. Federal Aviation Administration air traffic control system. To date, discussions of initial operations focus on using the visual abilities of the pilot to see-and-avoid (SAA) other aircraft. Decades of research on SAA has demonstrated that it is inadequate for reliable detection of aircraft that might pose a collision risk. The literature on multi-object tracking is also reviewed for findings on how well humans can visually track objects. This research shows that observers have limited resources for tracking and that this may be affected by object characteristics and cognitive resources. The conclusion is that SAA is a risky method for avoiding midair collisions. It is recommended that flight deck displays and automated collision avoidance systems be implemented in UAM aircraft at the outset of their introduction.