A Sensis Airport Surface Detection Equipment, Model X system (ASDE-X) is now operational at the Charlotte Douglas International Airport in Charlotte, NC.  ASDE-X uses a combination of surface movement radar, transponder multilateration and ADS-B sensors to provide air traffic controllers with an accurate picture of the location and identity of aircraft and vehicles on the airport surface.  In addition to providing controllers with a comprehensive picture of the airport surface, the ASDE-X system's conflict detection and alerting technology, Safety Logic, uses the most advanced algorithms available to detect and alert controllers to potential aircraft and vehicle collision situations.  Further, ASDE-X supports future technologies such as ADS-B for a seamless transition to the next generation air traffic surveillance system. The FAA is in the process of deploying the ASDE-X system to a total of 35 of the nation's airports. With the addition of Charlotte Douglas International, the system is operational and commissioned at eleven U.S. airports.