One of the major problems plaguing the airline industry in recent years has been the steady increase in the number and duration of flight delays. Airports have not been able to keep pace with the increase in air traffic. Consequently, Congress has directed the Federal Aviation Administration (FAA) to initiate programs to reduce delays and improve airport capacity. One program the FAA has initiated evaluates the simultaneous use of three and four closely spaced parallel runways. These operations would allow cost efficient capacity increases through concurrent use of already constructed runways and through the construction of additional runways at existing airports. Recent simulation studies have indicated that improvements in controller displays are required to safely conduct multiple parallel ILS approaches to runways spaced 4300 ft apart or less. This study was designed to quantify the ability of the Precision Runway Monitor (PRM) display to enhance controller performance over the current display, the Automated Radar Terminal System (ARTS) ILIA. Additionally, the effects of blunder degree and the number of simultaneous parallel approach operations (dual or triple approaches) on the controller's ability to detect aircraft blunders were also examined. A blunder is an unusually sharp turn by an aircraft off its ILS localizer course toward an adjacent ILS course. The PRM display, a high resolution raster scan color monitor, enhanced the controller's ability to quickly detect aircraft blunders over the ARTS ILIA display (the current display system), a Plan position Indicator (PPI). The average controller response times were smaller (4 seconds) and the average closest points of approach (CPAs) between the blundering and the evading aircraft were larger (776 ft) when the controllers used the PRM display. As in earlier studies, the thirty degree blunders resulted in conflicts that were more severe than the conflicts associated with twenty degree blunders. Conversely, contrary to earlier studies, the controllers were able to detect the twenty degree blunders as quickly as they detected thirty degree blunders. The controllers performed as well in the dual parallel approach operation as they did in the triple approach operation for all measures. The results of this study generally agreed with those found in earlier studies on controller performance. Controller performance can be improved with the use of high resolution displays with alert systems. However, unlike earlier studies, this study provided a quantification of the benefit of a proposed system relative to the current system. / Master of Science