Free flight represents a major change in the way that aircraft may be handled in the U.S. National Airspace System. It has the potential of significantly increasing airspace utilization and thus improving aircraft throughput. The degree to which these objectives can be met, however, without compromising aircraft safety, depends on establishing appropriate changes in the air traffic control system. These changes may include significant incorporation of new air traffic management and cockpit technologies. Studies that examine the affect of automation on situation awareness have been reviewed. These studies indicate that while certain forms of automation may be advantageous, other types of automation may induce losses in situation awareness that can lead to out−of−the−loop performance errors.