The U.S. Federal Aviation Administration (FAA) recently approved a national Flight Rules change for aircraft separation based on the data provided by Lockheed Martin's WindTracer Doppler lidar systems. Developed and produced by Lockheed Martin Coherent Technologies, WindTracer has been deployed at the Lambert-St. Louis International Airport since 2003 as part of the FAA Wake Turbulence Research Program for Closely Spaced Parallel Runways (CSPR). As a key result of the study, the FAA will soon allow large or small-class aircraft to land with a reduced spacing of 1.5 nautical miles to the leading large aircraft when landing on CSPRs with less than 2,500 ft separation. Current separation rules require that planes arriving on two such CSPRs be spaced as if they were using a single runway. This reduced separation will be implemented at five major U.S. airports with CSPRs, including Philadelphia International Airport, Seattle Tacoma International Airport, Lambert-St. Louis International Airport, Boston Logan International Airport and Cleveland Hopkins Airport. Each of these airports must still accomplish additional requirements prior to implementing this Flight Rules change. Ongoing efforts at these airports are expanding the CSPR capacity improvements to assess the departure phase of flight, and under what weather conditions departure spacing can be reduced. WindTracer has been used by the Federal Aviation Administration since 2001 to conduct wake vortex detection and tracking for consideration of national flight procedure changes. Systems are also performing wake-related functions at San Francisco International Airport, Houston Intercontinental Airport and Heathrow International Airport in London. The John A. Volpe National Transportation Systems Center, part of the U.S. Department of Transportation's Research and Innovative Technology Administration, provides data analysis and supports resources for the WindTracer deployments.