Today, each Air Navigation Service Provider (ANSP) determines a Secondary Surveillance Radar (SSR) code, composed of four digits from 0 to 7, that each individual flight is to use, or squawk in air ground communications.

SSR code shortages are a limiting factor to future growth in European air traffic levels and in traffic to new destinations within Europe. There are only 4096 Mode 3/A combinations to support identification and track-flight plan correlation of the flights.

By managing code assignment on a central basis, the most efficient code assignment can be achieved avoiding code changes and conflicts while coping with the increased traffic demand.


  • efficient management of SSR codes to avoid capacity constraints
  • reduction of code conflicts
  • reduction of code changes / workload
  • provision of additional SSR codes for special events and military exercises


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