The Global Maritime Distress and Safety System (GMDSS) is an internationally recognized distress and radio communication safety system for ships that replaced the previous ship-to-ship safety system that relied on manual Morse code operating on 500 kHz and voice radiotelephony on Channel 16 and on 2182 kHz.

The GMDSS is an automated ship-to-shore system using satellites and digital selective calling technology. The GMDSS is mandated for ships internationally by the International Maritime Organization (IMO) Safety of Life at Sea Convention (SOLAS), 1974, as amended in 1988, and carries the force of an international treaty.

The procedures governing use are contained in the International Telecommunications Union (ITU) recommendations and in the International Radio Regulations and also carry the force of an international treaty. There are many advantages of the GMDSS over the previous system, including:

• Provides worldwide ship-to-shore alerting; it is not dependent on passing ships.
• Simplifies radio operations; alerts may be sent by “two simple actions.”
• Ensures redundancy of communications; it requires two separate systems for alerting.
• Enhances search and rescue; operations are coordinated from shore centers.
• Minimizes unanticipated emergencies at sea; maritime safety broadcasts are included.
• Eliminates reliance on a single person for communications; it requires at least two licensed GMDSS radio operators and typically two maintenance methods to ensure distress communications capability at all times.

Radio officers (trained in manual Morse code) are not part of the GMDSS regulations or system. In lieu of a single radio officer, the GMDSS regulations require at least two GMDSS radio operators and a GMDSS maintainer if the ship elects at-sea repair as one of its maintenance options. The Federal Communications Commission (FCC) requires two licensed radio operators to be aboard all GMDSS-certified ships, one of which must be dedicated to communications during a distress situation.

The radio operators must be holders of a GMDSS Radio Operator’s License. The GMDSS radio operator is an individual licensed to handle radio communications aboard ships in compliance with the GMDSS regulations, including basic equipment and antenna adjustments. The GMDSS radio operator need not be a radio officer.

Another IMO convention requires all masters and mates to hold the GMDSS Radio Operator’s License and attend a two-week training course and demonstrate competency with operation of the GMDSS equipment. These requirements also would carry to any person employed specifically to act as a dedicated radio operator if the ship elected to carry such a position.

The international GMDSS regulations apply to “compulsory” ships, including:

• Cargo ships of 300 gross tons and over when traveling on international voyages or in the open sea.
• All passenger ships carrying more than 12 passengers when traveling on international voyages or in the open sea.

Fishing vessels to which GMDSS previously applied are under a waiver until a date to be announced in the future. The waiver is conditioned on the requirement that, for the duration of the waiver, fishing vessels of 300 gross tons or greater continue to carry a 406-MHz receiver and survival craft equipment including at least three portable VHF radiotelephones and two 9-GHz radar transponders. The GMDSS regulations do not apply to vessels operating exclusively on the Great Lakes.

GMDSS was mandated by international treaty obligations. In 1988, the International Maritime Organization (IMO), an organization of the United Nations, amended the Safety of Life at Sea (SOLAS) Convention to implement the GMDSS worldwide. The United States has been a strong advocate of the GMDSS internationally. In January 1992, the FCC adopted the GMDSS regulations for U.S. compulsory vessels. The only way to ensure compliance with GMDSS requirements is to use equipment that has been specifically approved by the FCC for GMDSS use.