A method of positioning a plurality of radar units in a defined area amongst one or more legacy radar units that provide legacy radar coverage in the defined area is disclosed. The steps of identifying a location of each legacy radar unit, setting a threshold altitude, and determining a legacy occultation of each legacy radar unit from a landscape level up to the threshold altitude are also disclosed. Mapping the legacy occultation of the legacy radar units to provide a three dimensional occultation map in the defined area and locating gaps below the threshold altitude in the legacy radar coverage as a function of the occultation map are also disclosed. Identifying a plurality of sites as a function of the gaps where the sites are accessible to receive a radar unit is also disclosed. Determining an anticipated radar coverage of a radar unit positioned at each of the sites and determining a reduction in the gaps as a function of the anticipated radar coverage are also disclosed. Selecting sites as a function of the reduced gaps is also disclosed. X band, C band or S band radar units can be positioned at the selected sites. The threshold altitude can be 10,000 or 15,000 feet. Affected populations and costs can also be considered in radar placement.