By ShipCalculators.com · Published 9 May 2026

LRIT Long-Range Identification and Tracking: SOLAS V/19-1 ship tracking

Long-Range Identification and Tracking (LRIT) is the mandatory satellite-based ship-position-reporting system established under Regulation 19-1 of Chapter V of the SOLAS Convention, adopted by IMO Resolution MSC.202(81) in May 2006 and entering force on 31 December 2008. LRIT requires every passenger ship including high-speed craft, every cargo ship of 300 GT and above including high-speed craft, and every mobile offshore drilling unit (MODU) on international voyages to transmit a position report comprising the IMO ship identifier, the MMSI, the WGS-84 latitude and longitude, and the UTC date and time at a default cadence of every 6 hours (four reports per day), with on-demand polling supported down to a 15-minute interval. The system architecture rests on four components: the Conformance Test Report (CTR) issued for each ship, the Application Service Provider (ASP) handling shipboard equipment and message routing, the LRIT Data Centre (DC) holding the flag-State position data, and the International Data Exchange (IDE) routing messages between Data Centres, operated by the European Maritime Safety Agency (EMSA) in Lisbon under IMO contract since the system went live. Access is granted at four tiers: Flag State (full access to own ships), Coastal State (within 1,000 nautical miles of own coast), Port State (ships intending to call at own ports), and SAR Authorities (full access for search-and-rescue purposes). The International Mobile Satellite Organisation (IMSO) performs the LRIT Coordinator audit function appointed by the IMO Maritime Safety Committee. LRIT complements but is distinct from the Automatic Identification System (AIS), which is short-range and line-of-sight, and from the Ship Security Alert System (SSAS) under SOLAS Chapter XI-2 maritime security and the ISPS Code. This article maps the LRIT regime to the SOLAS Chapter I general provisions, the Voyage Data Recorder, GMDSS, SOLAS Chapter IV radio communications, the ISM Code and the Polar Code; ShipCalculators.com hosts the calculator catalogue supporting tonnage-threshold determination, position-report cadence arithmetic, polling-interval planning and data-fee budgeting.

Contents

Background: post-9/11 maritime security framework

The case for a global mandatory ship-tracking regime grew out of a sequence of high-consequence maritime security incidents that exposed the weakness of the ability to identify and locate large merchant ships beyond coastal radar and AIS range. The Achille Lauro hijacking on 7 October 1985, in which a Palestine Liberation Front cell seized the Italian-flag cruise ship off Egypt and murdered the passenger Leon Klinghoffer, demonstrated that a passenger ship in international waters could become a hostage-taking target with no reliable position feed available to responders. The bombing of the USS Cole on 12 October 2000 in Aden, Yemen, killed seventeen US sailors and signalled that both naval and merchant maritime targets sat within the planning envelope of trans-national terrorism. The 11 September 2001 attacks crystallised the recognition that civilian transport assets including merchant ships could be weaponised, with maritime cargo and the global container chain identified as a particular concern.

The IMO Maritime Safety Committee placed maritime security on its highest-priority agenda in December 2001, and a Diplomatic Conference at IMO headquarters in December 2002 adopted the ISPS Code and the supporting amendments to SOLAS Chapter XI-2, in force 1 July 2004. Among the measures introduced was the Ship Security Alert System (SSAS) under SOLAS XI-2/6, a covert silent alarm from ship to flag State. SSAS solved the alarm problem but not the position-reporting problem: authorities still had no mandatory, system-wide ship-location feed beyond AIS line-of-sight range.

The LRIT proposal was tabled at MSC by the United States and supported by the European Union, Japan, Norway, the Republic of Korea, Australia and other flag and coastal States. Drafting work proceeded through 2004 and 2005 in MSC and the NAV Sub-Committee, addressing position-report cadence, message content, bearer choice, data architecture, access tiers and cost recovery. MSC 81 in May 2006 adopted Resolution MSC.202(81) introducing Regulation 19-1 into SOLAS Chapter V, together with Resolution MSC.210(81) (performance standards) and Resolution MSC.211(81) (arrangements for timely establishment). The amendments entered force on 31 December 2008 under the SOLAS tacit-acceptance procedure.

SOLAS V/19-1 application: passenger + cargo ≥300 GT + MODU

Regulation 19-1 of SOLAS Chapter V applies to ships engaged on international voyages in three categories:

Passenger ships including high-speed passenger craft of any size. The threshold is qualitative: a small HSC ferry crossing an international boundary is in scope on the same basis as a 6,000-passenger cruise ship.
Cargo ships including high-speed craft of 300 GT and above. The 300 GT threshold matches SOLAS Chapter IV GMDSS carriage; cargo ships below 300 GT are outside LRIT.
Mobile Offshore Drilling Units (MODU) on international voyages. A MODU on station is not on an international voyage; once underway between locations across an international boundary it is in scope.

The Regulation 19-1.4 exemptions cover ships engaged exclusively on voyages within Sea Area A1 with operational AIS, on the rationale that continuous AIS coverage substitutes for a satellite feed. Warships, naval auxiliaries and government non-commercial service are outside SOLAS scope. Flag States may exempt individual ships, with exemptions reported to IMO and subject to PSC scrutiny abroad.

Existing ships were phased in through 1 July 2009 for Inmarsat-C-equipped tonnage; by the close of the phase-in period the entire SOLAS-applicable fleet on international voyages sat within the LRIT envelope.

IMO MSC.202(81) adoption May 2006

The Maritime Safety Committee at its 81st session (10 to 19 May 2006, IMO headquarters London) adopted Resolution MSC.202(81) introducing the new Regulation 19-1 into SOLAS Chapter V, issued as MSC 81/25/Add.1.

The drafting compromise reflected three points of negotiation. First, the information set was deliberately limited to identity, position and time, excluding speed and course except on polling, to address flag-State concerns about commercial confidentiality. Second, the cadence was set at six hours by default rather than the more frequent rate sought by some coastal States, on cost-confidentiality grounds and on the bearer-economics of Inmarsat-C. Third, the access tiers were calibrated: flag State full access as sovereign right; coastal State access within a 1,000 nm radius and only for ships not bound for its ports; port State access only for intending callers; SAR authority full access without geographic restriction.

Companion resolutions at the same session were MSC.210(81) (performance standards and functional requirements) and MSC.211(81) (arrangements for timely establishment, covering IDE, Coordinator and data-flow architecture). MSC.263(84) of May 2008 refined the performance standards in the light of early operational experience.

Entry into force: 31 December 2008

The amendment text was deemed accepted on 1 July 2008 under the SOLAS tacit-acceptance procedure of Article VIII(b) and entered force on 31 December 2008 without objection. The implementation timeline ran in parallel: the IDE procurement was conducted by IMO during 2007 and 2008, with EMSA selected as IDE operator and the LRIT Coordinator function awarded to IMSO; individual flag-State Data Centres were stood up through 2008 and 2009, and the first operational LRIT position reports were exchanged in late 2008 and early 2009.

Position reporting: 6-hour default cadence

Under Resolution MSC.210(81) and MSC.1/Circ.1259 (currently Revision 7), a ship within scope transmits a position report every 6 hours by default, totalling four reports per day. The report is initiated by the shipboard LRIT terminal (Inmarsat-C or MiniC with LRIT-conformant firmware), with the ASP forwarding to the flag-State Data Centre.

T_{\text{position report}} = 6 \text{ hours default}

The four-per-day cadence balances coastal-State and SAR utility against the bearer cost of Inmarsat-C messages: at typical 50 to 100 bytes per report, the per-report bearer cost is in the low single-digit cents at wholesale Inmarsat-C tariffs, totalling a modest annual operating expense per ship.

The cadence is suspended in two circumstances: when the ship is within Sea Area A1 with operational AIS (the LRIT requirement is exempted for the duration), and when the ship is in defined laid-up status (the flag State may suspend the data feed temporarily). The cadence is increased on demand by polling.

On-demand polling: down to 15-minute interval

The LRIT system supports on-demand polling at intervals as short as 15 minutes under Resolution MSC.210(81). The polling request flows from the requesting Data Centre through the IDE to the flag-State Data Centre to the ASP and the shipboard terminal; the response is routed back the same path.

T_{\text{polling minimum}} = 15 \text{ minutes on-demand}

The 15-minute floor is rarely used outside specific contexts (a SAR operation, a piracy intercept, a ship of security concern, a vessel in distress); routine polling operates at one-hour or four-hour intervals. The polling response is the only context in which speed over ground is included; the routine 6-hour cadence omits speed. The architecture supports cascade and selective polling, and the IDE logs all requests for IMSO audit.

Report content: IMO + MMSI + lat/lon WGS-84 + UTC + speed

The LRIT position report contains, under Resolution MSC.210(81):

Ship identifier: the seven-digit IMO number (SOLAS XI-1/3) and the nine-digit MMSI (ITU Radio Regulations).
Position: latitude and longitude in decimal degrees on the WGS-84 datum, the same datum used by AIS and GNSS (GPS, GLONASS, Galileo, BeiDou).
Date and time: UTC date and time of fix in ISO 8601 format.
Speed and course (polling only): speed over ground in knots and course over ground in degrees true, omitted from the routine 6-hour cadence.

The report is wrapped in a routing header (flag State, Data Centre ID, ship ID, sequence number for audit). Total payload runs 80 to 150 bytes per report depending on bearer encoding.

Architecture component 1: Conformance Test Report (CTR)

Every ship within scope must hold a valid LRIT Conformance Test Report (CTR) issued by an organisation recognised by the flag State (typically a classification society or flag-State testing body). The CTR certifies that the shipboard equipment, the ASP arrangement and the data flow to the flag-State Data Centre conform to MSC.210(81) and MSC.1/Circ.1259.

The CTR is issued after bench testing against the type-approval certificate, on-board commissioning testing, end-to-end message-flow testing through the ASP to the Data Centre, and verification of IDE-side acknowledgment. The CTR is carried on board (electronic copy acceptable) and is subject to PSC inspection. It is renewed when the equipment, ASP, or flag changes; there is no fixed expiry interval, but the CTR remains valid only while the underlying equipment, ASP arrangement and Data Centre routing remain unchanged.

Architecture component 2: Application Service Provider (ASP)

The Application Service Provider (ASP) is the commercial entity that operates the shipboard-equipment-to-Data-Centre interface. The ASP configures the LRIT terminal with the correct Data Centre routing, handles bearer connectivity (Inmarsat-C or MiniC), forwards position reports to the flag-State Data Centre, and handles polling requests routed back to the ship.

Principal ASPs include Inmarsat acting as ASP for some flags, Pole Star Global Tracking Solutions (UK), CLS Collecte Localisation Satellites (France), Wartsila (formerly Transas), Cobham SATCOM (formerly Thrane and Thrane), Furuno, JRC, Mackay Communications (US) and EMSA-contracted ASPs for smaller flags. ASP selection is the operator’s commercial decision, subject to flag-State approval. ASP service fees typically run a few hundred US dollars per ship per year covering bearer-cost reimbursement, message-handling, technical support, and the CTR-renewal interface.

Architecture component 3: LRIT Data Centre (DC)

The LRIT Data Centre (DC) holds the position reports for ships of a flag State. Each SOLAS contracting government must establish or contract for a Data Centre. Three options are available under MSC.210(81):

National Data Centre: the flag State stands up its own DC. Examples: USCG LRIT National Data Centre, UK MCA, Marshall Islands, Liberia, Panama.
Regional Data Centre: two or more flag States share a DC. The largest is the EU LRIT Data Centre operated by EMSA covering EU Member-State flags collectively.
Cooperative Data Centre (CDC): smaller flag States lacking capacity join a shared DC under IMO and Coordinator administration with the same data-handling guarantees.

The Data Centre receives, stores and forwards position reports; responds to access requests from coastal, port and SAR authorities through the IDE; logs all access for IMSO audit; and interfaces with the CTR framework for fleet enrolment.

Architecture component 4: International Data Exchange (IDE) Lisbon

The International Data Exchange (IDE) is the central message-routing hub of LRIT. The IDE does not hold position-report data: it is a stateless router that accepts a message from a Data Centre and forwards it to the destination Data Centre, applying the access-tier rules at routing.

The IDE was established under MSC.211(81), procured by IMO during 2007 and 2008, and operated by EMSA from facilities in Lisbon, Portugal co-located with the EU SafeSeaNet ship-tracking system, providing redundancy and 24-hour operations. The IDE handles routing for all SOLAS-applicable ships globally, with daily volumes in millions of position reports plus thousands of polling requests and response-time targets in the seconds range.

EMSA operating IDE under IMO contract since 2009

The European Maritime Safety Agency (EMSA) is an EU agency established by Regulation (EC) No 1406/2002 with a mandate covering maritime safety, security and pollution response. EMSA was selected as IDE operator in 2008 and took operational responsibility from mid-2009.

The IMO-EMSA contract is renewed periodically and has run without significant service-compromising outages. EMSA recovers costs through a fee structure paid by IDE users (the receiving Data Centres and ultimately the access-tier authorities consuming reports), broadly budget-neutral on a multi-year basis. EMSA’s role is purely technical and routing-focused; it has no enforcement role. Audit is performed by IMSO under the LRIT Coordinator role, with annual reports to the MSC.

Communications Service Provider (CSP): Inmarsat-C / MiniC / Iridium

The LRIT Communications Service Provider (CSP) is the satellite operator providing the bearer link from shipboard equipment to ASP. Recognised CSP options:

Inmarsat-C: the original LRIT bearer, dominant on legacy fits. Low-data-rate store-and-forward with global L-band coverage outside the polar regions (above approximately 76 degrees latitude). Robust, mature, low-cost.
Inmarsat MiniC: the current new-build standard, a compact replacement for Inmarsat-C with lower power consumption, smaller antenna and integrated NMEA 0183. Type-approved by Cobham SATCOM, JRC, Furuno and others.
Iridium: approved for polar operation above 76 degrees where Inmarsat L-band coverage falls below the horizon, with comprehensive low-Earth-orbit polar coverage supporting Polar Code operations.
Inmarsat FleetBroadband / Fleet Xpress: recognised where the operator runs the LRIT message on the broader ship-comms terminal.

CSP is part of the type-approval certification; bearer substitution requires CTR re-issuance.

Access tier 1: Flag State full access

The Flag State has full access to position reports for all ships flying its flag, without geographic restriction, at any cadence including the 15-minute polling minimum, without per-message charges (the flag State funds its own DC and ASP). Flag-State access is the cornerstone of the regime, grounded in the sovereign right to know the position of the merchant fleet. The flag-State DC is the primary repository and routing point for all incoming access requests.

Major National Data Centres are operated by the USCG, UK MCA, Marshall Islands, Liberia, Panama, Bahamas, Singapore MPA, Hong Kong Marine Department, Hellenic Coast Guard, Norwegian Maritime Authority and others; smaller flag States participate through Regional or Cooperative Data Centres.

Access tier 2: Coastal State within 1,000 nm

The Coastal State accesses position reports for ships within 1,000 nautical miles of its coast, irrespective of flag, on the rationale that ships within that radius sit within the response time of coastal-State authorities for security, environmental and SAR purposes.

d_{\text{coastal access}} = 1{,}000 \text{ nm from coast}

The 1,000 nm radius is measured from the territorial-sea baseline under UNCLOS 1982, extending well beyond the 200 nm EEZ as a security-driven extension into the high seas. Coastal-State access is paid per consumed report; the coastal State submits its access-area to the IDE, which routes qualifying ships automatically. Ships intending to call at a port of the coastal State are excluded from the 1,000 nm tier and routed under the port-State tier instead, to avoid double-billing.

Access tier 3: Port State for intended port calls

The Port State accesses position reports for ships intending to call at one of its ports, irrespective of flag and current position, grounded in the port-State authority to inspect and deny entry under the SOLAS and regional MoU frameworks.

Access begins when the ship declares intent (typically through the 24-hour pre-arrival notification under SOLAS XI-2/9 for ISPS port facilities) and continues until port entry (after which AIS provides local tracking) or call cancellation. Access is paid on the same per-report basis as coastal-State access. Major port-State Data Centres include the USCG (US arrivals), the EMSA EU Data Centre (EU arrivals), AMSA (Australian arrivals) and the Japan Coast Guard.

Access tier 4: SAR Authorities full access

SAR Authorities have full access to position reports for any ship anywhere, without geographic restriction, without data fees, and including the 15-minute polling minimum, when the request supports search-and-rescue operations.

SAR access reflects the priority of life-saving under the SAR Convention 1979 and the GMDSS framework. Access is granted to Maritime Rescue Coordination Centres (MRCC), to Joint Rescue Coordination Centres (JRCC) where SAR is coordinated with aviation, and to other authorised SAR responders. In an active operation the MRCC or JRCC may poll any ship in the search area for current position, course and speed. The SAR tier was used in the MV El Faro loss of October 2015, where LRIT data confirmed the last reported position before loss of contact in Hurricane Joaquin.

Relationship to AIS (short-range vs LRIT long-range)

The Automatic Identification System (AIS) under SOLAS V/19.2.4 and LRIT under V/19-1 are complementary but operationally distinct.

AIS is short-range, line-of-sight, terrestrial-VHF on the dedicated channels at 161.975 and 162.025 MHz. The AIS message includes IMO, MMSI, position, course, speed, navigational status, dimensions, draft, cargo type and destination, broadcast every 2 to 10 seconds (Class A) or 30 seconds to minutes (Class B). AIS is received by other ships within VHF range (typically 30 to 40 nm), coastal AIS shore stations, and satellite-AIS in low-Earth orbit (S-AIS, with message-collision losses in dense traffic).

LRIT is long-range, satellite-based, low-cadence: identity, position and time (speed on polling), every 6 hours by default. LRIT is restricted to authorised parties under access-tier rules and is not visible to the public or other ships.

AIS provides the high-cadence collision-avoidance picture; LRIT provides the strategic security-focused tracking layer. Modern integrated bridges display both on ECDIS or dedicated tracking displays.

Relationship to SSAS Ship Security Alert System

The Ship Security Alert System (SSAS) under SOLAS XI-2/6 is a separate covert silent alarm distinct from LRIT. SSAS is activated by the master or designated officers in a piracy, armed-robbery or security incident, transmitting a covert alert to the flag-State authority and the company-designated security officer without alerting other ships or the perpetrators.

The SSAS message includes ship identity and position at activation. It runs on the same satellite-comms terminal as LRIT (typically Inmarsat-C or MiniC) but on a separate logical channel to a different destination (the flag-State security operations centre, not the LRIT Data Centre). SSAS is regulated under SOLAS Chapter XI-2 maritime security and the ISPS Code, not SOLAS V/19-1.

The systems are complementary: LRIT provides the routine baseline; SSAS provides the exceptional covert alarm. After SSAS activation the flag State and coastal State typically poll LRIT at high cadence to track the ship through the security-incident response.

Data fees: ~USD 0.05-0.20 per position report

LRIT operates on a cost-recovery basis with data fees charged per consumed report. The schedule is set by the IDE operator under the IMO contract and is periodically reviewed.

\text{Cost per report} \in [0.05, 0.20] \text{ USD}

Typical fees have been USD 0.05 to 0.20 through the system’s operational life, varying with bearer-cost evolution and IDE cost recovery. Polling is charged at a higher per-message rate than routine 6-hour reports. The flag State funds only its own DC and ASP costs; coastal and port States pay per consumed report; SAR authorities consume without payment. A coastal State with 1,000 nm access tracking ~5,000 ships at four reports per day consumes ~20,000 messages per day, costing on the order of USD 0.5 to 1.5 million per year, a modest line item against the wider security and SAR budgets of major coastal States.

IMSO audit role

The International Mobile Satellite Organisation (IMSO) is the inter-governmental organisation established in 1979 to oversee Inmarsat’s public-service obligations and now performs the GMDSS Mobile Satellite Service audit role and the LRIT Coordinator function under SOLAS V/19-1.

Under MSC.211(81) IMSO performs the annual audit covering the IDE (EMSA), the Data Centres, the ASPs and the end-to-end data flow, verifying performance standards, access rules, fee application and overall service delivery. Audit reports go to the MSC for consideration; findings are addressed through MSC instructions to participants. IMSO also arbitrates disputes between LRIT participants on data-access, fees and conformance.

LRIT Coordinator appointed by IMO MSC

The LRIT Coordinator is the institutional role under MSC.211(81) providing independent oversight on behalf of the MSC. The Coordinator is appointed by the MSC for a renewable term and was awarded to IMSO at MSC 84 in May 2008 with subsequent renewals.

Responsibilities are: conducting the annual audit; approving the IDE operator and verifying conformance; approving Data Centres on stand-up; reviewing the fee structure and reporting to MSC on cost recovery; arbitrating disputes between participants; and reporting to each MSC session on system performance, audit findings and policy. The Coordinator function operates as a fee-for-service IMO contract, recovered through the broader LRIT fee structure.

Cooperative Data Centre (CDC) for flag states without own DC

The Cooperative Data Centre (CDC) is the option for flag States lacking the technical capacity, budget or fleet size to support a stand-alone National or Regional DC. The framework was established under MSC.1/Circ.1259 and is operated by IMO through the LRIT Coordinator.

A CDC is operated by a host country or international organisation accepting LRIT data-handling for participating flags on contract, with multiple smaller flags sharing a single CDC and the same data-handling functions as a National DC. The CDC option addresses the universality principle of SOLAS: the regime is mandatory for all SOLAS-applicable ships, and CDC ensures workability across the full diversity of the flag-State universe.

Regional Data Centres: France, Germany, Korea, Norway, Spain, Turkey

Several flag States and regional groupings operate Regional Data Centres sharing infrastructure across participating administrations:

EU LRIT Data Centre operated by EMSA in Lisbon, serving the EU Member States collectively, the largest globally by message volume and participating flags.
France, Germany, Italy, Greece, Spain and Portugal participate in the EU Regional DC with national-level supplementary arrangements where required.
Republic of Korea operates a National DC at the Korea Coast Guard Maritime Cyber Operations Center.
Norway operates a National DC at the Norwegian Coastal Administration covering Norwegian-flag and NIS fleet.
Turkey operates a National DC at the Directorate General of Coastal Safety.
Russia operates a National DC at the Federal Agency for Maritime and River Transport.
China operates the DC at the Maritime Safety Administration; Japan at the Japan Coast Guard.

The diversity of arrangements reflects the diversity of national maritime administrations and the flexibility of the V/19-1 framework.

US Coast Guard LRIT Operating Center

The USCG LRIT National Data Centre and LRIT Operating Center are operated from the Maritime Information Exchange in Washington DC with supporting facilities at the Coast Guard Intelligence Coordination Center, Suitland Maryland. The Operating Center supports the US flag-State role for US-flagged ships and the US coastal-State and port-State roles for arrivals at US ports.

The US LRIT framework was established under 33 CFR Part 169 and has been in service since 31 December 2008. It is integrated with the wider USCG maritime-domain awareness suite including the Nationwide AIS (NAIS), the MDA Common Operating Picture, cutter and aircraft tracking, and the DHS maritime intelligence framework. The Center handles approximately 100,000 to 200,000 reports per day across the flag, coastal and port-State entitlements, supporting maritime security, SAR and law-enforcement operations.

Typical equipment: Inmarsat-C terminal + MiniC

Shipboard LRIT equipment falls into three terminal classes:

Inmarsat-C is the legacy LRIT-conformant terminal, with type approvals across Cobham SATCOM Sailor 6110/6120/6130 series, JRC JUE-87/95LT/250, Furuno Felcom 18/19, Saab TT-3000E and others. The Inmarsat-C terminal is also approved for SOLAS IV GMDSS Class 2 ship-radio carriage in Sea Areas A1, A2 and A3.
Inmarsat MiniC is the current new-build standard, with a smaller antenna, lower power and a more compact below-deck unit, dual-purpose for GMDSS and LRIT (Cobham, JRC, Furuno).
Iridium LRIT terminals are approved for polar operation, with type-approved units from Iridium Communications and Lars Thrane LT-3100S.

Installation comprises the above-deck antenna, below-deck transceiver, GNSS-receiver feed for position, UTC time source, and ASP and flag-State DC routing configuration. Power is from the ship’s emergency 24V DC bus with battery backup per type approval.

Polar Code intersection: LRIT mandatory

The Polar Code under SOLAS Chapter XIV entered force on 1 January 2017 for ships operating in defined Arctic and Antarctic waters. The Polar Code does not separately mandate LRIT; the V/19-1 requirement already applies to all SOLAS-applicable ships on international voyages, including Polar-Code ships.

The Polar Code interaction is in the bearer-choice dimension: Inmarsat L-band coverage is limited above approximately 76 degrees latitude where the geostationary satellites fall below the horizon, so ships operating in high-latitude polar waters need Iridium as the LRIT bearer with corresponding CTR re-issuance. The Polar Code also imposes voyage-planning and SMS obligations supported by the LRIT strategic-tracking baseline.

Class society type-approval: DNV, LR, ABS, BV, NK, RINA, KR, CCS, RS, IRS

LRIT equipment is type-approved by major classification societies as recognised organisations under flag-State delegation. IACS members issuing LRIT type approvals include DNV (Hovik), Lloyd’s Register (London), ABS (Houston), Bureau Veritas (Paris La Defense), ClassNK (Tokyo), RINA (Genoa), Korean Register (Busan), China Classification Society (Beijing), Russian Maritime Register of Shipping (St Petersburg) and Indian Register of Shipping (Mumbai), with Polish (PRS) and Croatian (CRS) registers also active.

Type-approval verifies the LRIT performance standards under MSC.210(81), bearer-specific testing (Inmarsat-C, MiniC, Iridium), the general performance standards under IMO Resolution A.694(17), and the IEC 60945 environmental and EMC testing standards. The certificate is valid for a defined configuration and remains valid as long as the equipment is not modified. The ship-specific CTR is issued separately on the basis of the type approval, the ASP arrangement, and the end-to-end conformance test of the installation.

PSC inspection: CTR + functionality

Port-State Control of LRIT compliance addresses two principal items:

CTR documentation: the Conformance Test Report must be available on board (paper or electronic). Missing or invalid CTR is a recurring deficiency, escalating to detention in serious cases.
LRIT functionality: the inspector may verify that the terminal is operational, that the most recent report has been transmitted, and that routing is correctly configured. A non-functional terminal is a deficiency requiring rectification before departure or before the next port.

PSC inspection sits within the wider SOLAS V navigation-equipment scope, operated under the Paris MoU, Tokyo MoU, USCG, Vina del Mar Agreement, Indian Ocean MoU, Mediterranean MoU, Black Sea MoU, West and Central African MoU and Riyadh MoU. Annual deficiency statistics show LRIT deficiencies in low single-digit percentages, with most classified as “rectify before departure” rather than detention.

2024 IMO MSC modernisation review

The MSC at successive sessions through 2023, 2024 and 2025 has reviewed LRIT modernisation in the light of 16 years of operational experience and developments including satellite AIS (S-AIS), VDES and cyber-resilience.

Principal modernisation options under review:

Optional 1-hour cadence as an alternative to the 6-hour default, providing higher-cadence coastal-State and SAR awareness without invoking the 15-minute polling fee structure.
AIS-LRIT integration at the DC level, enabling fused tracking displays without changing the underlying regulatory frameworks.
Cyber-resilience of the LRIT system itself across the ASP-DC-IDE chain. MSC.428(98) applies to the operator’s SMS but not directly to LRIT architecture; explicit cyber standards are under MSC consideration.
Refined fee structure updating the per-report tariff for bearer-cost and IDE-cost evolution.

No mandatory amendments to V/19-1 or MSC.210(81) have been adopted at writing; the review is in the consultative phase with submissions from flag States, IMSO, EMSA and the satellite operators.

VDES + AIS-2 + LRIT integration outlook

Looking to the 2030 horizon, the tracking landscape is evolving toward an integrated multi-bearer ecosystem:

VHF Data Exchange System (VDES) as the successor to AIS, providing higher data rates on maritime VHF (with AIS backwards-compatible), supporting terrestrial and satellite reception, and enabling digital chart updates, route exchange, and MSI broadcast at higher rates than the SafetyNET GMDSS framework. The first VDES satellite is in LEO and the system is expected to grow through the late 2020s.
AIS-2 as the evolved terrestrial AIS standard with extended messages, higher robustness and VDES interoperability, in ITU-R standardisation.
LRIT integration with VDES and AIS-2 harmonising at the DC and access-tier level while preserving the distinct legal and security characteristics of each regime.
Satellite AIS (S-AIS) as a commercial complement used by coastal States and intelligence services as a supplement to the regulatory feeds.
Cyber-resilient tracking with hardened bearer authentication, end-to-end message integrity and resilient multi-network routing.

The LRIT regime under V/19-1 is expected to remain the primary mandatory long-range tracking framework through this evolution, with technical modernisation rather than wholesale replacement.

Formula, assumptions, and limits

Formula

The LRIT cadence is governed by the default 6-hour interval and the 15-minute polling minimum:

T_{\text{position report}} = 6 \text{ hours default (4 reports/day)}

T_{\text{polling minimum}} = 15 \text{ minutes on demand}

The carriage-threshold formula applies to passenger ships of any size, cargo ships of 300 GT and above, and MODU on international voyages:

\text{GT}_{\min} = 300 \text{ for cargo ships (passenger and MODU not size-thresholded)}

The coastal-State access radius is 1,000 nm from the territorial sea baseline:

d_{\text{coastal access}} = 1{,}000 \text{ nm from coastal baseline}

The data-fee structure is per consumed position report:

\text{Cost per report} \in [0.05, 0.20] \text{ USD}

Derivation

The 6-hour cadence balanced coastal-State and SAR utility against bearer-cost economics at 2006 adoption: four reports per day at Inmarsat-C tariffs is well within the operator’s de-minimis budget and provides sufficient resolution to detect significant course changes and support SAR position estimation. The 15-minute polling minimum is the shortest interval supportable on Inmarsat-C store-and-forward without overload, given satellite-message latency and the on-demand fee structure. The 300 GT cargo threshold was inherited from SOLAS IV GMDSS on the rationale that LRIT runs on the same equipment class and that smaller tonnage is dominated by short-sea trade where LRIT adds limited value over AIS. The 1,000 nm coastal-State radius reflects a security and SAR response-distance compromise: 200 nm EEZ was too short, a global tier politically infeasible; 1,000 nm corresponds to approximately two days’ steaming at typical merchant-ship speed.

Assumptions

The LRIT regime assumes that:

The shipboard equipment is correctly type-approved, correctly installed, and correctly configured to the flag-State Data Centre.
The satellite bearer (Inmarsat-C, MiniC, Iridium, FleetBroadband or other approved bearer) provides reliable connectivity over the operational area of the ship.
The ASP correctly routes messages to the flag-State Data Centre.
The flag-State Data Centre correctly stores the data and correctly responds to access requests.
The IDE correctly applies the access-tier rules and correctly routes messages to receiving Data Centres.
The receiving Data Centre correctly stores the data and correctly displays it to the access-tier authority’s operational staff.
The CTR has been issued and is current.

Worked example

A 35,000 GT bulk carrier flying the Marshall Islands flag operates Newcastle Australia to Qingdao China, departing 1 May 2026 with arrival 18 May 2026. LRIT cadence and access-tier consumption:

Four routine reports per day at 0000, 0600, 1200 and 1800 UTC, totalling 72 reports over the 18-day voyage.
Marshall Islands (flag) consumes all 72 reports at no charge.
Australia (coastal) consumes ~6 reports while within 1,000 nm of the coast (~1.5 days) at USD 0.05 to 0.20 each.
Papua New Guinea, Solomon Islands, Indonesia and the Philippines consume reports within their respective 1,000 nm radii.
China (port) consumes ~8 to 12 reports from pre-arrival notification (24 to 72 hours) until port entry.

Total ship-side bearer cost is ~USD 5 to 10 in routine messaging; total data-fee revenue across consuming parties is ~USD 5 to 30.

Edge cases and limits

Ship within Sea Area A1 with operational AIS: LRIT is suspended on an exemption basis.
Ship in laid-up status: the flag State may suspend the data feed temporarily, restored on return to service.
Polar operation above 76 degrees latitude: Inmarsat L-band coverage is limited; Iridium bearer required with CTR re-issuance.
Bearer outage: minor outages cause message loss recovered by the next routine report; persistent failure is a serious deficiency.
Data Centre outage: a flag-State DC outage of more than 24 hours triggers IMO and IMSO notification and emergency reroute.
IDE outage: EMSA operates redundant infrastructure with disaster-recovery to mitigate this risk.
Cyber compromise: a cyber attack on ASP, DC or IDE is a serious incident under MSC.428(98).
Spoofing: false LRIT messages purporting to come from a victim ship; IDE access rules and DC validation reduce but do not eliminate the risk.
Flag transfer mid-voyage: requires new-flag DC configuration and CTR re-issuance before transfer.
MODU on station: outside the LRIT cadence requirement until underway across an international boundary.
Warship and government non-commercial service: outside SOLAS scope and the LRIT regime.

Regulatory basis

SOLAS Chapter V Regulation 19-1 (Long-Range Identification and Tracking of Ships), as amended.
IMO Resolution MSC.202(81) (May 2006) Adoption of amendments to SOLAS Chapter V introducing Regulation 19-1.
IMO Resolution MSC.210(81) (May 2006) Performance standards and functional requirements for LRIT.
IMO Resolution MSC.211(81) (May 2006) Arrangements for the timely establishment of the LRIT system.
IMO Resolution MSC.263(84) (May 2008) Revised performance standards and functional requirements for LRIT.
IMO MSC.1/Circ.1259 LRIT system technical documentation (revised through Revision 7).
IMO Resolution A.694(17) (1991) General requirements for shipborne radio equipment.
IMO Resolution MSC.428(98) (2017) Maritime cyber risk management in safety management systems.
IEC 60945 Maritime navigation and radiocommunication equipment - General requirements.
IEC 61097 series for Inmarsat-C and other satellite-bearer equipment testing.
ITU Radio Regulations for MMSI assignment and bearer-frequency allocation.
UNCLOS 1982 for the territorial-sea baseline definition underlying the 1,000 nm coastal-State access radius.

Common errors

Treating LRIT as an AIS substitute: both are required where applicable; neither satisfies the other’s carriage requirement.
Treating LRIT as an SSAS substitute: SSAS is a separate covert alarm under SOLAS XI-2/6; LRIT provides no alarm function.
Assuming LRIT data is public: it is restricted to the four authorised access tiers and is not published.
Misunderstanding the coastal-State radius: the 1,000 nm radius is from the territorial-sea baseline and applies regardless of flag.
Stale CTR: failing to renew after equipment replacement, ASP change or flag change is a recurring PSC deficiency.
Assuming the 6-hour cadence is fixed: it is the default; flag States may require higher cadence, and access-tier parties may poll to the 15-minute minimum.
ASP routing misconfiguration: a not-uncommon installation error pointing reports to the wrong DC.
Treating LRIT as outside cyber scope: MSC.428(98) covers the operator’s SMS including LRIT integrity.
Confusing the LRIT and GMDSS frameworks: a single physical terminal may serve both, but the regulatory frameworks and CTR documentation are distinct.
Assuming LRIT covers warships: SOLAS does not apply to warships and naval auxiliaries.

References

The principal source for SOLAS Chapter V Regulation 19-1 carriage of LRIT equipment is the IMO consolidated text of the International Convention for the Safety of Life at Sea, 1974, as amended, available from the IMO publishing service and the IMO Knowledge Centre, with Regulation 19-1 supplying the carriage threshold for passenger ships of any size, cargo ships of 300 GT and above and MODU on international voyages, and providing the access-tier framework for flag, coastal, port and SAR authorities. The adoption text is IMO Resolution MSC.202(81) of May 2006, with companion Resolution MSC.210(81) establishing the performance standards and functional requirements (the technical specification covering message content, cadence, polling and the four-component architecture of CTR, ASP, Data Centre and IDE) and Resolution MSC.211(81) establishing the arrangements for timely establishment (the institutional framework, IDE procurement, LRIT Coordinator role and data-flow architecture). The performance standards were refined by Resolution MSC.263(84) of May 2008. The implementation technical documentation is supplied by IMO MSC.1/Circ.1259 in successive revisions through Revision 7, covering message protocols, routing rules, access-tier procedures and the audit framework. The horizontal performance standard for shipborne radio equipment is IMO Assembly Resolution A.694(17) of 1991, with international electrotechnical testing standards in IEC 60945 and the IEC 61097 series for satellite-bearer equipment. MMSI numbering and bearer-frequency allocation is governed by the ITU Radio Regulations. The cyber-risk-management framework applicable to the operator’s SMS covering LRIT integrity is IMO Resolution MSC.428(98) of 2017. The IDE operating role is performed by the European Maritime Safety Agency (EMSA) in Lisbon under IMO contract since 2009; the LRIT Coordinator role is performed by the International Mobile Satellite Organisation (IMSO) under MSC appointment. Major flag-State Data Centres are operated by the United States Coast Guard, the United Kingdom MCA, the Marshall Islands, Liberia, Panama, the Bahamas, Singapore, Hong Kong, Korea, Norway, Russia, China, Japan and a wider universe of national, regional and cooperative arrangements covering the full SOLAS contracting-government population. The classification-society framework is set out by IACS with type-approval certificates issued by IACS member societies (DNV, Lloyd’s Register, ABS, Bureau Veritas, ClassNK, RINA, Korean Register, China Classification Society, Russian Maritime Register of Shipping, Indian Register of Shipping and others) covering the principal manufacturers (Cobham SATCOM, JRC, Furuno, Saab, Iridium Communications, Lars Thrane). Port-State-control enforcement runs through the Paris MoU, the Tokyo MoU, the USCG and the regional MoU agreements covering the Caribbean, Latin America, the Indian Ocean, the Mediterranean, the Black Sea, West and Central Africa, and the Gulf. The post-9/11 maritime-security framework underlying LRIT is set out in the IMO Diplomatic Conference of December 2002, the SOLAS Chapter XI-2 amendments and the ISPS Code. The casualty record where LRIT data has been used in SAR includes the MV El Faro loss of October 2015 and a wider record of abandonment, ferry capsize and missing-vessel cases reported through the IMO GISIS Marine Casualties and Incidents module.