SSR code shortages are becoming 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.
Current SSR code management
The SSR codes are currently managed under the ICAO Originating Region Code Assignment Method (ORCAM) system. The ORCAM system is based on strategic allocations of sets of codes to individual States and the alternate use of transit and local definition of codes per Participating Areas (PAs): codes use for transit in one PA are used for local purposes in adjacent PAs. All together they cover the entire ICAO EUR Region.
The need for change
Since the mid 1990s, individual States have been forecasting potential shortages in their allotments of SSR codes to meet the forecast growth in air traffic.
Until now, changes to the ORCAM rules, Flight Data Processing System (FDPS) functionality upgrades, and close coordination between States, have ensured no major safety or capacity issues would arise on a routine basis.
Increasingly since 2000, ORCAM States have been raising serious concerns about the ability to meet future demand using the existing SSR code management methodology, for the following reasons:
The basis of ORCAM are the traffic flows and Participating Areas (PA) structure, designed over 20 years ago.
- The geo-political map of Europe changed.
- New States needed to be allotted with SSR codes.
- The use of secondary radar in neighbouring ICAO regions, such as Africa and Mid-Asia, is leading to more limitations in code usage.
- The levels of air traffic have risen considerably over the last decade and forecasts indicate that the level of traffic will continue to increase significantly.
- The instances of SSR code conflicts are increasing and are suffered by many of the ORCAM States.