As part of the NextGen Surveillance and Weather Radar Capability (NSWRC) program, the Federal Aviation Administration (FAA) is currently developing the solution for aircraft and meteorological surveillance in the future National Airspace System (NAS). A potential solution is a multifunction phased array radar (MPAR) that would replace some or all of the single-purpose radar types used in the NAS today. One attractive aspect of MPAR is that the number of radars deployed would decrease, because redundancy in coverage by single-mission sensors would be reduced with a multifunction system. The lower radar count might then result in overall life cycle cost savings, but in order to estimate costs, a reliable estimate of the number of MPARs is needed. Thus this report addresses the question, "If today's weather and aircraft surveillance radars are replaced by a single class of multimission radars, how many would be needed to replicate the current air space coverage over the United States and its territories?" Various replacement scenarios must be considered, since it is not yet determined which of the organizations that own today's radars (the FAA, the National Weather Service (NWS), the different branches of the U.S. military) would join in an MPAR program. It updates a previous study using a revised set of legacy systems, including 81 additional military airbase radars. Six replacement scenarios were considered, depending on the radar mission categories. Scenario 1 would replace terminal radars only, i.e., the Airport Surveillance Radars (ASRs) and the Terminal Doppler Weather Radar (TDWR). Scenario 2 would include the Scenario 1 radars plus the long-range weather radar, commonly known as NEXRAD. Scenario 3 would add the long-range aircraft surveillance radars, i.e., the Air Route Surveillance Radars (ARSRs), to the Scenario 2 radars. To each of these three scenarios, we then add the military's Ground Position Navigation (GPN) airbase radars for Scenarios 1G, 2G, and 3G. We assumed that the new multimission radar would be available in two sizes--a full-size MPAR and a scaled-down terminal MPAR (TMPAR). Furthermore, we assumed that the new radar antennas would have four sides that could be populated by one, two, three, or four phased array faces, such that the azimuthal coverage provided could be scaled from 90 degrees to 360 degrees. Radars in the 50 United States, Guam, Puerto Rico, U.S. Virgin Islands, Guantanamo Bay (Cuba), and Kwajalein (Marshall Islands) were included in the study.