SSR Codes

 Mode 3/A code allocation information

Regular Requests

SSR codes required for the prolonged use for traffic management or for discrete identification purposes are considered to be regular allocations.  Application for regular allocation of an SSR code may take up to four months to be fully assessed, consulted upon and subsequently published.  SSR codes are a scarce resource and as such a rigorous assessment must be completed prior to any allocation.  In the first instance any organisation requiring the regular allocation of an SSR code should e-mail or write to SS3 providing the following information:

  1. Name of organisation requiring codes.
  2. Details of any codes already allocated to that organisation.
  3. Number of codes required.
  4. Details of preferred codes.
  5. Requirement for codes.  For example a Police Air Support Unit requesting a single code for discrete identification; or an ATSP requesting codes for air traffic control.
  6. If requesting codes for air traffic control, details of the current and future number of movements to be handled by the ATSP.
  7. If requesting a code for discrete identification, the areas of operation of any aircraft wearing that code should be provided.
  8. Contact details (name & number).

Whilst it is possible that follow-up information may be required, the above information should be provided as a minimum before any requirement can begin to be assessed.

Mindful that SSR codes are a finite resource that must be effectively managed to meet the needs of aviation at both a national and European level, it should be noted that the allocation of a code or set of codes to a specific controlling agency does not imply any right over the continued use of that allocation. Following appropriate coordination with the controlling agency and other interested stakeholders it may, on occasion, be necessary to withdraw or reallocate codes for reasons of efficiency or higher priority requirements.

Temporary Requests

SSR codes may be allocated on a temporary basis for the same purposes as described above.  Normally temporary allocations are for military exercises and civil special events such as air shows.  Whilst the assessment criteria for temporary requests are similar to regular requests, the need for wider consultation, the potential impact on other airspace users and the requirement for formal widespread publication can be mitigated against due to the transitory nature of such allocations.  Temporary requests should be submitted on the SSR NOTAM Application Form.  SSR NOTAM Application Forms should ideally be submitted not less than one month prior to the first proposed use of the codes.  There are a finite number of codes available and assignment cannot be guaranteed.

Contact Details:  


020 7453 6534
020 7453 6565 
Surveillance & Spectrum Management
Directorate of Airspace Policy
Civil Aviation Authority
CAA House
45-59 Kingsway