Which radar system is primarily used for en-route air traffic control?

The Air Route Surveillance Radar (ARSR) is primarily utilized for en-route air traffic control as it is specifically designed to monitor aircraft over vast distances at cruising altitudes. This radar system provides continuous surveillance of en-route traffic, enabling air traffic controllers to maintain situational awareness and ensure safe separation between aircraft flying at high altitudes.

ARSR systems are capable of detecting both primary and secondary radar signals, allowing for the tracking of transponder-equipped aircraft. This is vital for managing air traffic across large sectors and ensuring the efficiency of flight routes in controlled airspace.

Other radar systems, such as the Airport Surface Detection Equipment (ASDE), typically focus on monitoring ground operations and aircraft movements on the airport surface, while Terminal Doppler Weather Radar (TDWR) is mainly designed to provide information about weather conditions, especially in the vicinity of airports. Secondary Surveillance Radar (SSR) enhances tracking capabilities but is not a standalone system specifically designed for en-route control; it works in conjunction with primary systems to facilitate traffic management. Thus, the ARSR stands out as the most appropriate choice for en-route air traffic control.