Extended Operational and Trade Vocabulary

GMDSS Equipment and Survival Craft Communications glossary

The GMDSS-equipment vocabulary: the sea areas (A1 to A4) under SOLAS IV/2, DSC and EPIRB equipment, survival-craft communications, and the distress-alerting and search-and-rescue-locating terms. Grounds each term in the GMDSS regulation or the survival-craft communications requirement it belongs to.

203 defined terms.

A

A1 Sea Area: GMDSS area within VHF DSC coverage of at least one coast station, typically 20 to 30 nautical miles.
A2 Sea Area: GMDSS area within MF DSC coverage of at least one coast station, excluding A1, typically out to 100 to 200 nautical miles.
A3 Sea Area: GMDSS area within geostationary satellite (Inmarsat) coverage, excluding A1 and A2, roughly 76 N to 76 S.
A4 Sea Area: GMDSS area outside A1, A2 and A3, comprising the polar regions above 76 latitude.
ACR ARTEX ELT: Emergency Locator Transmitter line manufactured by ACR Electronics for aviation use, transmitting on 406 MHz to the Cospas-Sarsat system with 121.5 MHz homing signal.
ACR Electronics: US manufacturer of EPIRBs, PLBs and AIS-SARTs (e.g., GlobalFix V4/V5).
ACR GlobalFix V5 EPIRB: Category II 406 MHz Cospas-Sarsat EPIRB from ACR Electronics with internal 66-channel GPS receiver and 121.5 MHz homing transmitter.
ACR ResQLink View PLB: Personal Locator Beacon from ACR Electronics transmitting on 406 MHz Cospas-Sarsat with integrated GPS and digital display showing operating status and GPS fix confirmation.
AIS Channel 87B: 161.975 MHz VHF marine channel allocated as AIS 1.
AIS Channel 88B: 162.025 MHz VHF marine channel allocated as AIS 2.
AIS-SART: AIS Search and Rescue Transmitter for survival craft.
AMP Marine Equipment Approval: Common shorthand for Marine Equipment Directive approval under EU Directive 2014/90/EU, indicated by the Wheelmark symbol on compliant equipment.
Annual Performance Test (APT): Yearly shore-based test of a Voyage Data Recorder performed by a certified service supplier per IMO MSC.1/Circ.1222.
ARTEX: Aviation beacon brand historically produced by ARTEX Aircraft Supplies, later acquired by ACR Electronics; the ELT product line includes models such as the ME406 and C406.

B

Battery Reserve: Minimum six hour emergency power reserve required under SOLAS Regulation IV/13 to operate the radio installation when the main and emergency sources of electrical power have failed.
BDMSS: BeiDou Maritime Safety System, China's maritime safety information broadcast service designated by IMO Resolution MSC.498(105) for use in the modernized GMDSS.
Beacon Identification Code: 15 hexadecimal character (60 bit) or 22 hexadecimal character (87 bit) identifier encoded in a 406 MHz beacon message, programmed into Cospas-Sarsat first generation and second generation beacons.
BeiDou SAR Payload: Search and Rescue payload planned for BeiDou navigation satellites as China's MEOSAR contribution to Cospas-Sarsat.

C

Category I EPIRB: Float free EPIRB installed in a hydrostatic release bracket that automatically releases the beacon when submerged to approximately four meters depth.
Category II EPIRB: Manually deployed EPIRB stored in a bracket that requires a person to remove and activate the beacon.
Channel 16: VHF international distress, safety and calling channel, 156.800 MHz.
Channel 70: VHF Digital Selective Calling channel, 156.525 MHz; voice prohibited.
China BDMSS: BeiDou Maritime Safety System recognized as a recognized mobile satellite service by IMO Resolution MSC.498(105) for distribution of Maritime Safety Information.
Class A AIS: SOLAS-grade AIS unit transmitting at up to 12.5 W with SOTDMA access.
Class B AIS: Non-SOLAS AIS unit transmitting at 2 W with CSTDMA access.
Cobham SAILOR 100 GX: Inmarsat Global Xpress Ka band terminal with 1.0 m antenna from Cobham SATCOM.
Cobham SAILOR 150 FleetBroadband: Compact mini FleetBroadband terminal operating over the Inmarsat I-4 satellites with simultaneous voice and IP data.
Cobham SAILOR 250 FleetBroadband: Inmarsat FBB terminal with 25 cm antenna providing up to 284 kbit per second over Inmarsat I-4.
Cobham SAILOR 3965 UHF/VHF: Portable two way radio from Cobham used for on board communications, with variants for UHF and VHF frequencies.
Cobham SAILOR 4300 L-Band: Iridium Certus L band terminal from Cobham SATCOM providing data and voice over the Iridium NEXT constellation.
Cobham SAILOR 500 FleetBroadband: Inmarsat FBB terminal with 60 cm antenna providing up to 432 kbit per second.
Cobham SAILOR 60 GX: Inmarsat Global Xpress Ka band terminal with 60 cm antenna from Cobham SATCOM.
Cobham SAILOR 6110 mini-C: Inmarsat C and mini C terminal from Cobham SATCOM used for GMDSS distress, MSI reception, and SafetyNET messaging.
Cobham SAILOR 6210 VHF DSC: GMDSS Class A VHF DSC radio from Cobham SATCOM with integrated Channel 70 watch keeping receiver.
Cobham SAILOR 6248 VHF: VHF radiotelephone from Cobham SATCOM in the SAILOR 6000 series.
Cobham SAILOR 6300 MF/HF: GMDSS MF and HF radio console from Cobham SATCOM, formerly Thrane and Thrane.
Cobham SAILOR 6320 Iridium Certus: Iridium Certus terminal from Cobham SATCOM operating over the Iridium NEXT constellation.
Cobham SAILOR 6390 NAVTEX: NAVTEX receiver from Cobham SATCOM operating on 518 kHz, 490 kHz, and 4209.5 kHz frequencies.
Cobham SAILOR Iridium Pilot: Iridium OpenPort terminal previously marketed under the SAILOR brand for voice and data over the legacy Iridium constellation.
Cobham Sea Tel: Maritime VSAT antenna brand from Cobham SATCOM, including the 9711, 9797, and USAT product families.
Consilium VDR: Voyage Data Recorder product line from Consilium Marine, type approved per IMO Resolution MSC.333(90).
Cospas-Sarsat: International satellite system for 406 MHz distress beacon detection.
Cospas-Sarsat T.001: Cospas-Sarsat document specifying the technical requirements for first generation 406 MHz distress beacons.
Cospas-Sarsat T.018: Cospas-Sarsat document specifying the technical requirements for second generation 406 MHz beacons including Return Link Service support.

D

Datrex: United States manufacturer of marine survival equipment including hydrostatic release units, EPIRB brackets, and emergency rations.
Distress alert: GMDSS message indicating grave and imminent danger.
DSC: Digital Selective Calling per ITU-R M.493 and ITU-R M.541.
DSC Class A: Highest category of DSC equipment compliant with ITU-R M.493 capable of all calls on all frequencies, required on SOLAS vessels.
DSC Class D: Reduced functionality DSC equipment for VHF used on non SOLAS vessels.

E

EGC: Enhanced Group Call service over Inmarsat (SafetyNET and FleetNET).
ELT: Emergency Locator Transmitter, automatic 406 MHz distress beacon fitted to helicopters.
EPIRB: Emergency Position-Indicating Radio Beacon required under SOLAS IV/7.
EPIRB-AIS: EPIRB with integrated AIS Message 1 locator (e.g., Ocean Signal rescueME EPIRB3).
Explorer 500: Cobham Thrane fixed BGAN terminal from the EXPLORER series operating over Inmarsat I-4 satellites.
Explorer 727: Cobham Thrane vehicular BGAN terminal from the EXPLORER series with auto pointing antenna.

F

FastFind 220: McMurdo personal locator beacon transmitting on 406 MHz Cospas-Sarsat with integrated GPS and 121.5 MHz homing.
Felcom 12: Legacy Furuno Inmarsat C maritime mobile earth station.
Felcom 14: Legacy Furuno Inmarsat C maritime mobile earth station with GMDSS distress functionality.
Felcom 15: Furuno Inmarsat C maritime mobile earth station compliant with GMDSS and SafetyNET requirements.
Felcom 16: Furuno Inmarsat mini C maritime mobile earth station for GMDSS use.
Felcom 17: Furuno Inmarsat C maritime mobile earth station succeeding the Felcom 16.
Felcom 18: Furuno Inmarsat mini C maritime mobile earth station for GMDSS Class 2 service.
First Generation Beacon (FGB): 406 MHz Cospas-Sarsat beacon compliant with document T.001, in service since 1985 and planned for phase out by 2030.
FleetBroadband: Inmarsat L-band IP service in 150, 250 and 500 kbps classes (e.g., FB150, FB250, FB500).
FleetNET: Inmarsat EGC service for commercial broadcast to fleet subscribers.
Float Free Bracket: Mounting bracket with a hydrostatic release that allows an EPIRB to deploy automatically when submerged below approximately four meters.
FM-8800S: Furuno VHF DSC Class A radiotelephone for SOLAS vessels.
FM-8900S: Furuno VHF DSC Class A radiotelephone for SOLAS vessels with integrated Channel 70 watch receiver.
FS-1575: Furuno MF/HF SSB transceiver with DSC at 150 W output for GMDSS A2 and A3 service.
FS-2575: Furuno MF/HF SSB transceiver with DSC at 250 W output for GMDSS A3 and A4 service.
FS-5070: Furuno MF/HF SSB transceiver with DSC at higher output power for GMDSS A3 and A4 service.
Furuno NX-300: Furuno NAVTEX receiver operating on 490 kHz, 518 kHz, and 4209.5 kHz.
Furuno NX-700A: Furuno NAVTEX receiver with dual frequency operation on 490 kHz and 518 kHz.

G

Galileo Return Link Service: Service operated by the European Union Agency for the Space Programme transmitting an acknowledgment from the Cospas-Sarsat ground segment to a second generation beacon via the Galileo navigation…
Galileo SAR: SAR payload hosted on Galileo MEOSAR satellites by the European Commission.
Garmin inReach: Two way satellite messenger operating over the Iridium constellation with SOS service routed through Garmin Response, not a Cospas-Sarsat beacon.
GEOSAR: Geostationary segment of Cospas-Sarsat providing near-real-time alerting without Doppler position.
GlobalFix V5: ACR Electronics Category II 406 MHz EPIRB with internal GPS.
GMDSS: Global Maritime Distress and Safety System under SOLAS Chapter IV.
GMDSS Maintainer's License: ITU/STCW qualification for personnel responsible for at sea maintenance of GMDSS radio equipment.
GMDSS Modernization: Program adopted by IMO Resolutions MSC.496(105) and MSC.497(105) in 2022 revising functional requirements and admitting additional service providers.
GMDSS Operator Certificate: STCW endorsement for Global Maritime Distress and Safety System radio operators.
GOC: General Operator's Certificate for GMDSS, the operator qualification required for sea areas A2, A3, and A4 under the ITU Radio Regulations and STCW.
GPS Block IIIA: United States GPS satellites carrying the SAR/GPS payload contributing to Cospas-Sarsat MEOSAR coverage.

H

Hammar H20: Hydrostatic release unit manufactured by C. M. Hammar of Sweden, releasing an EPIRB or VDR capsule when submerged to approximately four meters depth.
HF DSC: HF Digital Selective Calling on 4207.5, 6312, 8414.5, 12577 and 16804.5 kHz.
Homing Signal: 121.5 MHz auxiliary signal transmitted by 406 MHz EPIRBs and PLBs used by SAR aircraft and vessels for direction finding at close range.
HRU: Hydrostatic Release Unit releasing the float free EPIRB at depth.

I

IHO: International Hydrographic Organization, intergovernmental body for hydrography.
Inmarsat C: Polling/EGC/SafetyNET service in GMDSS.
Inmarsat Mini-C: Smaller-antenna variant of Inmarsat C used widely for distress, safety, and tracking.
Intellian C700: Iridium Certus L band terminal from Intellian Technologies operating over the Iridium NEXT constellation.
Intellian C700 GX: Hybrid terminal pairing Intellian's Iridium Certus C700 with Inmarsat Global Xpress capability.
Intellian v100: Maritime Ku band VSAT antenna from Intellian Technologies with 1.0 m reflector.
Intellian v110: Maritime Ku band VSAT antenna from Intellian Technologies with 1.1 m reflector.
Intellian v130: Maritime Ku band VSAT antenna from Intellian Technologies with 1.25 m reflector.
Intellian v150 NX: Maritime Ku band VSAT antenna from Intellian Technologies with 1.5 m reflector and NX series electronics.
Intellian v240MT: Multi band maritime VSAT antenna from Intellian supporting C, Ku, and Ka band operation.
Iridium 9603SBD: Short Burst Data transceiver module from Iridium Communications used as the core of small satellite communication products.
Iridium Certus: L-band satellite broadband service (GMDSS-recognized 2020).
Iridium Certus 200: Iridium Certus service class with up to 176 kbps uplink and 176 kbps downlink.
Iridium Certus 700: Iridium Certus service class with up to 352 kbps uplink and 704 kbps downlink.
Iridium NEXT: Second-generation Iridium constellation of 66 LEO satellites whose deployment was completed in January 2019.
Iridium SafetyCast: GMDSS Maritime Safety Information service via Iridium.
ITU MMSI: Maritime Mobile Service Identity issued under ITU Radio Regulations as a unique nine digit number assigned to each maritime radio station.

J

JCY-1900: JRC voyage data recorder and simplified VDR family.
Jotron: Norwegian manufacturer of EPIRBs (Tron 60), AIS-SARTs and VHF/MF/HF radios.
Jotron NAV-7: Jotron NAVTEX receiver operating on 490 kHz, 518 kHz, and 4209.5 kHz.
Jotron Tron 60 SART: Jotron 9 GHz X band radar Search and Rescue Transponder responding to interrogation by ship and aircraft radars.
Jotron Tron 60GPS EPIRB: Jotron 406 MHz Cospas-Sarsat EPIRB with internal GPS receiver.
Jotron Tron 60S+ SART: Improved variant of the Jotron 9 GHz radar SART.
Jotron TRON 80AIS-SART: Jotron AIS Search and Rescue Transmitter for survival craft and lifeboat use.
Jotron Tron AIS-SART: Jotron AIS Search and Rescue Transmitter operating on AIS channels 87B and 88B.
Jotron Tron HF DSC: Jotron MF/HF DSC controller compliant with GMDSS A2, A3, and A4 requirements.
Jotron Tron TR20 GMDSS: Jotron GMDSS two way portable VHF radio in safety yellow for survival craft use.
Jotron Tron TR30: Jotron GMDSS two way portable VHF radio in safety yellow for survival craft use, succeeding the TR20.
Jotron Tron VHF DSC: Jotron Class A VHF DSC radiotelephone for GMDSS use.
JRC: Japan Radio Co., manufacturer of MF/HF, Inmarsat C and AIS equipment.
JRC JHS-2110: JRC Class A VHF DSC radiotelephone for GMDSS use, succeeding earlier JHS series radios.
JRC JHS-770S: JRC Class A VHF DSC radiotelephone for GMDSS use.
JRC JSS-2150: JRC 150 W MF/HF SSB transceiver with DSC for GMDSS A2 service.
JRC JUE-87: JRC Inmarsat mini C maritime mobile earth station for GMDSS use.
JRC JUE-95SA: JRC Inmarsat C maritime mobile earth station for GMDSS use, sometimes packaged as a Mini-C variant for specific markets.
JRC NCR-300A: JRC NAVTEX receiver operating on 518 kHz and 490 kHz.
JRC NCR-333: JRC NAVTEX receiver with three frequency reception on 490 kHz, 518 kHz, and 4209.5 kHz.

K

Kelvin Hughes VDR: Voyage Data Recorder product line historically supplied by Kelvin Hughes, now part of the Hensoldt UK family.
KVH TracPhone V11: KVH Industries hybrid C band and Ku band maritime VSAT antenna with 1.1 m reflector.
KVH TracPhone V7: KVH Industries Ku band maritime VSAT antenna with 60 cm reflector.

L

Lars Thrane LT-3100S: Iridium SafetyCast capable GMDSS satellite terminal manufactured by Lars Thrane A/S of Denmark, type approved for the Iridium maritime safety service.
LEOSAR: Low Earth Orbit segment of Cospas-Sarsat providing Doppler localization.
Lifebuoy Light: Self igniting battery powered light fitted to lifebuoys, required by SOLAS LSA Code Chapter II.
Lifejacket Light: Battery powered or chemically activated light fitted to lifejackets, required by SOLAS LSA Code Chapter II.
LSA Code: International Life-Saving Appliance Code, mandatory under SOLAS III/34.

M

M10: Marine Rescue Technologies M10 AIS man overboard device transmitting on AIS channels 87B and 88B.
Marine Rescue Technologies: United Kingdom manufacturer of AIS man overboard devices including the M10 series.
McMurdo FastFind 220: McMurdo personal locator beacon transmitting on 406 MHz Cospas-Sarsat with internal GPS.
McMurdo Group: United Kingdom manufacturer of GMDSS equipment historically based in Portsmouth, producing the SmartFind, FastFind, and NAV product lines.
McMurdo NAV6 Plus: McMurdo NAVTEX receiver operating on 518 kHz, 490 kHz, and 4209.5 kHz.
McMurdo R10 AIS MOB: McMurdo AIS man overboard device transmitting on AIS channels 87B and 88B.
McMurdo R5 GMDSS: McMurdo two way portable VHF radio in safety yellow for survival craft use.
McMurdo S20 MOB: McMurdo AIS man overboard device transmitting on AIS channels 87B and 88B.
McMurdo SmartFind G8 EPIRB: McMurdo 406 MHz Cospas-Sarsat EPIRB with internal 66-channel GPS.
McMurdo SmartFind R5 AIS SART: McMurdo AIS Search and Rescue Transmitter operating on AIS channels 87B and 88B.
McMurdo SmartFind R5 SART: McMurdo 9 GHz X band radar Search and Rescue Transponder.
McMurdo SmartFind S5 PLB: McMurdo personal locator beacon transmitting on 406 MHz Cospas-Sarsat.
MED: Medical Care, STCW VI/4 paragraph 2.
MEOSAR: Medium Earth Orbit segment of Cospas-Sarsat on GPS, Galileo and GLONASS, enabling rapid global localization.
MF DSC: Medium Frequency Digital Selective Calling on 2187.5 kHz.
MF/HF DSC Distress Watch: Continuous automatic monitoring of MF and HF DSC distress frequencies required of GMDSS equipped vessels operating in sea areas A2, A3, and A4.
MID: Maritime Identification Digits, the first three digits of an MMSI indicating country of registration.
MMSI: Maritime Mobile Service Identity, 9-digit per ITU-R M.585.
MOB1: Ocean Signal personal AIS man overboard device with DSC alerting that transmits on AIS channels 87B and 88B upon activation.

N

NAVAREA: One of 21 navigational warning areas under the Worldwide Navigational Warning Service relevant to incident broadcasts.
NAVDAT: Navigational Data system operating on MF 500 kHz and HF, an emerging digital broadcast service for Maritime Safety Information defined by ITU-R M.2010.
NAVTEX: GMDSS broadcast service under SOLAS IV.
NBDP: Narrow-Band Direct Printing (radiotelex), ITU-R M.476/M.625.

O

Ocean Signal: UK manufacturer of compact EPIRBs (rescueME EPIRB1 and EPIRB3) and AIS-SARTs (rescueME MOB1).
Ocean Signal rescueME EDF1: Ocean Signal electronic distress flare with LED light source.
Ocean Signal rescueME EPIRB1: Ocean Signal compact 406 MHz Cospas-Sarsat EPIRB with internal 66-channel GPS.
Ocean Signal rescueME MOB1: Ocean Signal personal AIS man overboard device with DSC alerting transmitting on AIS channels 87B and 88B.
Ocean Signal rescueME PLB1: Ocean Signal personal locator beacon transmitting on 406 MHz Cospas-Sarsat with internal GPS.
Ocean Signal rescueME SART: Ocean Signal 9 GHz X band radar Search and Rescue Transponder.
Ocean Signal SafeSea E101G EPIRB: Ocean Signal Category I/II 406 MHz Cospas-Sarsat EPIRB with internal GPS.
Ocean Signal SafeSea V100 GMDSS: Ocean Signal two way portable VHF radio for survival craft use.

P

Plastimo HRU: Hydrostatic release unit manufactured by Plastimo of France for liferaft and EPIRB deployment at approximately four meters depth.
PLB: Personal Locator Beacon transmitting on 406 MHz Cospas-Sarsat; not GMDSS equipment.
Polar Coverage: HF radio coverage required in sea area A4 (above 76 degrees North and below 76 degrees South) where geostationary satellites are not visible.

R

Return Link Service (RLS): Service whereby a Cospas-Sarsat second generation beacon receives an acknowledgment of alert reception via the Galileo navigation message, defined in Cospas-Sarsat document T.018.
ROC: Restricted Operator Certificate.
Rutter VDR-100G3: Voyage Data Recorder produced by Rutter Inc. of Canada compliant with IMO Resolution MSC.333(90).

S

SafetyCast: Iridium GMDSS broadcast service approved in 2020.
SafetyNET I: Inmarsat C/EGC service broadcasting Maritime Safety Information defined by IMO Resolution A.701(17).
SafetyNET II: Inmarsat enhanced safety broadcast service.
SAR/Galileo: Search and Rescue payload carried on Galileo navigation satellites contributing to Cospas-Sarsat MEOSAR.
SAR/GLONASS: Search and Rescue payload carried on Russian GLONASS-K navigation satellites contributing to Cospas-Sarsat MEOSAR.
SAR/GPS: Search and Rescue payload carried on United States GPS Block IIIA satellites contributing to Cospas-Sarsat MEOSAR.
SART: Search and Rescue Transponder, with the AIS SART variant transmitting on AIS frequencies.
Sea Marshall AU9: Personal AIS man overboard device produced by Sea Marshall Rescue Systems.
Second Generation Beacon (SGB): Cospas-Sarsat 406 MHz distress beacon compliant with document T.018, supporting Return Link Service and improved encoding.
Skanti TRP 8400: MF/HF SSB transceiver with DSC originally produced by Skanti of Denmark for GMDSS service.
SmartFind G8: McMurdo Category I/II 406 MHz EPIRB with internal GPS.
SmartFind R5 AIS SART: McMurdo AIS Search and Rescue Transmitter.
SmartFind R5 SART: McMurdo 9 GHz X band radar SART.
SmartFind S5 PLB: McMurdo personal locator beacon transmitting on 406 MHz Cospas-Sarsat.
SOLAS Chapter IV: Radiocommunications, including GMDSS requirements.
SVDR: Simplified Voyage Data Recorder for cargo ships built before 1 July 2002, performance standard in IMO Resolution MSC.163(78).

T

Thales VesseLINK 700: Iridium Certus terminal manufactured by Thales operating over the Iridium NEXT constellation.
Trimble Galaxy: Legacy Inmarsat C maritime mobile earth station originally produced by Trimble Navigation.
Tron 60GPS: Jotron 406 MHz Cospas-Sarsat EPIRB with internal GPS.
Tron AIS-SART: Jotron AIS Search and Rescue Transmitter operating on AIS channels 87B and 88B.
Tron TR20: Jotron GMDSS two way portable VHF radio in safety yellow.
Tron TR30: Jotron GMDSS two way portable VHF radio in safety yellow succeeding the TR20.
Type Approval Certificate: Issued by a class society or flag administration for equipment.

V

VDR: Voyage Data Recorder, required under SOLAS V/20.
VDR Fixed Capsule: Fire and shock protected capsule mounted in a position likely to survive a sinking, retaining the last 12 to 48 hours of recorded data.
VDR Float Free Capsule: Capsule fitted with a hydrostatic release unit designed to float free of a sinking vessel and broadcast a 406 MHz locating signal.
Vesper WatchMate XB-8000: Vesper Marine SOLAS Class B AIS transponder with integrated NMEA 2000 and Wi-Fi data sharing.
VHF DSC Watch: Continuous automatic monitoring of VHF Channel 70 required of GMDSS equipped vessels in sea area A1 and above.
VR-3000: Furuno simplified VDR meeting IMO Resolution A.861(20).
VR-7000: Furuno VDR meeting the revised IMO Resolution MSC.333(90) performance standard.
VR-7000S: Furuno Simplified Voyage Data Recorder variant of the VR-7000 for cargo ships under 3,000 GT.
VSAT: Very Small Aperture Terminal satellite system used for two-way broadband at sea.

W

Wheelmark: Conformity mark required for marine equipment placed on the EU market under Directive 2014/90/EU.