LRIT (Long Range Identification & Tracking)

What sets LRIT apart

LRIT is not a navigation instrument the bridge team reads — it is a reporting system that transmits a ship's identity, position and the time of that position to shore authorities automatically every six hours, with no chart display and no watchkeeping function on board. Unlike AIS, which broadcasts openly to any receiver in range, LRIT sends data only to the flag state and, on request, to port and coastal states, and it works globally by satellite rather than being limited to VHF range near the coast.

Main components

Shipborne transmitting equipment

A satellite communication terminal, typically Inmarsat-C or equivalent, configured to poll the ship's position from GPS and transmit identity, position and timestamp automatically at the required interval without operator action.

Application Service Provider (ASP)

The shore-based link between the ship's terminal and the flag state's data centre, handling the message format and routing rather than the raw satellite communication itself.

Data Centre and Data Distribution Plan

The flag state's LRIT Data Centre stores position reports and releases them according to a Data Distribution Plan that defines which coastal and port states may request the ship's data and under what conditions.

Regulations and class

LRIT is mandatory under SOLAS Chapter V, Regulation 19-1, for passenger ships, cargo ships of 300 gross tonnage and above on international voyages, and mobile offshore drilling units. The requirement is transmission of position at least every six hours, with the system able to be polled more frequently by the flag state. Class or a recognised organisation on the flag state's behalf verifies conformance testing was carried out and issues a Conformance Test Report, without which the certificate cannot be endorsed.

Typical faults

• Terminal loses GPS input while the satellite link stays up — position reports transmit with stale or no coordinates, and the fault can go unnoticed on the bridge since there is no visible alarm on most integrations
• Airtime subscription lapses — LRIT reporting stops even though the underlying satellite terminal is functioning normally for other traffic
• Configuration reverted after a terminal software update — polling interval or destination address no longer matches the flag state's Data Distribution Plan
• Conformance testing not repeated after equipment replacement — certificate becomes technically invalid even though the new terminal reports correctly

What to look for in a supplier

• Confirmed conformance with the flag state's current LRIT Data Centre and Application Service Provider, since these vary and not every terminal integrates with every combination
• Integration path that does not depend solely on the ship's other satcom terminal, to avoid a single point of failure for both routine communications and mandatory reporting
• Support for remote reconfiguration if the vessel changes flag or ASP mid-life
• Documented conformance test history available for inspection at survey

What LRIT is not

Because LRIT shares a satellite terminal category with other systems, it is sometimes confused with Ship Security Alert System equipment or with the vessel's general satcom package. It performs none of those functions — it exists solely to satisfy the SOLAS position reporting requirement, and disabling it, even temporarily, is treated by flag states as a reportable deficiency rather than a maintenance choice left to the master's discretion.

If LRIT stops reporting, do not assume it is a terminal fault before checking the airtime subscription status — a lapsed subscription is a more common cause than hardware failure and is invisible from the bridge until someone checks it.