FCC rules require that licensees of ship, aircraft, and international fixed public radiocommunication stations permit only persons holding the appropriate FCC-issued commercial operator license to perform specified transmitter operation, maintenance and repair duties.


  • MPs are required to operate radiotelephone stations aboard certain vessels that sail the Great Lakes. They are also required to operate radiotelephone stations aboard vessels of more than 300 gross tons and vessels which carry more than six passengers for hire in the open sea or any tidewater area of the United States. They are also required to operate certain aviation radiotelephone stations and certain coast radiotelephone stations.
  • A PG is required to adjust, maintain, or internally repair FCC licensed radiotelephone transmitters in the aviation, maritime, and international fixed public radio services. It conveys all of the operating authority of the MP. It is also required to operate the following:

    • any maritime land radio station or compulsorily equipped ship radiotelephone station operating with more than 1500 watts of peak envelope power.
    • voluntarily equipped ship and aeronautical (including aircraft) stations with more than 1000 watts of peak envelope power.

  • Only persons whose commercial radio operator license bears this endorsement may repair, maintain, or internally adjust ship radar equipment.
  • The RG qualifies the holder to operate, and make some basic equipment adjustments to, Global Maritime Distress and Safety System (GMDSS) radio installations, but only on voyages that remain within twenty (20) nautical miles of shore. It also confers the operating authority of the MP.
  • The DO qualifies the holder to operate, and make some basic equipment adjustments to, Global Maritime Distress and Safety System (GMDSS) radio installations. It also confers the operating authority of the MP.
  • The DM qualifies personnel as GMDSS radio maintainers to perform at sea repair and maintenance of GMDSS equipment. It also confers the operating authority of the PG and MP.

    NOTE: In instances where an applicant qualifies for both a DO and a DM, the applicant qualifies to hold a GMDSS Radio Operator/Maintainer License (DB).
  • The DB confers the operating authority of the DO and the DM (and, by extension, it also confers the operating authority of the PG and MP).
  • The T3 authorizes operation of certain coast radiotelegraph stations. It also confers the operating authority of the MP.
  • The T2 authorizes the holder to operate, repair, and maintain ship and coast radiotelegraph stations in the maritime services. It also confers all of the operating authority of the T3 and MP.
  • A T1 is required only for those who serve as the chief radio operator on a U.S. passenger ship equipped with a radiotelegraph station. It also conveys all of the operating authority of a T2.