Three-Letter and Telephony Designators (3LD)

3LDs were designed to assist in the identification of airlines in flight.  These designators consist of a unique three-letter code which can be used for aircraft identification in a flight plan and/or a telephony designator which may be used as part of an aircraft's radiotelephony call sign [1]

The 3LD Online Request System facilitates States in the assigning of three-letter and telephony designators to agencies/airlines.  The 3LD system allows airlines to make requests for designators themselves directly, and have those requests automatically forward to the 3LD Focal Points each State for approval before assignment.

  • 3LD HOME PAGE contains general information regarding 3LDs (State Focal Points for 3LD will also find a link to sign into their state's Online-Tracking for designator requests on this page)
  • DELETE existing Designators

          3LD State Focal Points may make their request by email to

  • ACCESS 3LD Data
      • PURCHASE a copy of Designators for Aircraft Operating Agencies, Aeronautical Authorities and Services (Doc 8585) 
      • To obtain DATA DOWNLOADS of 3LDs, please contact

  • GENERAL ENQUIRIES regarding Three-letter and Telephony Designators can be made to

[1] Please note:  These ICAO designators are not to be confused with the IATA two-letter reservations codes.

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