Mode S (Selective Call) is an advanced secondary surveillance radar (SSR) system that offers several benefits and advantages over previous radar technologies:
Mode S improves aircraft identification and tracking capabilities by assigning unique 24-bit addresses to individual aircraft, called Mode S or ORAO (International Civil Aviation Organization) addresses. This feature enables more accurate and reliable aircraft identification in crowded airspace, reducing the likelihood of identification errors and improving the overall efficiency of air traffic management. Mode S addresses are also used in Automatic Dependent Surveillance-Broadcast (ADS-B) systems, allowing aircraft to broadcast their position, speed and other data to ground stations and other aircraft.
Another advantage of Mode S is its ability to support two-way data communication between aircraft and air traffic control (ATC) or other ground systems. This feature, known as Mode S Data Link (MODE S DLS), allows ATC to send messages directly to specific aircraft, providing critical information such as weather updates, aircraft changes, route and traffic advisories. This capability improves communication efficiency, reduces voice radio congestion, and supports more dynamic and responsive air traffic management operations.
Mode S also enhances the surveillance capability of SSR systems through the use of extended squitters and other advanced surveillance techniques. Extended Squitter allows aircraft equipped with Mode S transponders to periodically broadcast their identification, position and other information without requiring interrogation of ground radar stations. This improves situational awareness for ATC and other nearby aircraft, improving overall airspace safety and efficiency.
In summary, the benefits of Mode S include improved aircraft identification, improved tracking accuracy, two-way data communications capabilities, reduced voice radio, and improved surveillance capabilities through features such as extended squitter . These benefits make Mode S an important progression in air traffic management management and technology, supporting safer and more efficient operations in busy airspace environments.