VDR + LRIT + SSAS

Three distinct IMO tracking + data instruments together provide the technical basis for casualty investigation, flag/coastal-state monitoring, and merchant-ship security-alert response. Each has its own SOLAS regulation, retention rule, and data-request procedure. All three are routinely audited at PSC inspection + play a central role in casualty investigation.

Voyage Data Recorder (VDR) — SOLAS V/20

A shipborne recorder capturing ship data (position, heading, speed, engine parameters, watertight door status, bridge audio, radar image, ECDIS image) continuously to a protected memory. Function is analogous to an aircraft "black box". Required on all passenger ships + cargo ships > 3,000 GT constructed on or after 1 July 2002 (subsequently amended to include existing ships).

• Retention. Minimum 48 hours in the protected float-free capsule; longer in the primary recorder + optional back-up.
• Simplified VDR (S-VDR). Reduced data-capture version for cargo ships > 3,000 GT constructed before 2002 + retrofitted.
• Post-incident data retrieval. After a casualty, the VDR is preserved intact + data downloaded by casualty investigators. Regular VDR data may be pulled for post-voyage analysis or training.
• Annual performance test required by IMO Res. A.861(20).
• Investigation use. Cases where VDR data has been central: Costa Concordia, El Faro (recovered from wreck), MV Grande America, Ever Given.

Long Range Identification and Tracking (LRIT) — SOLAS V/19-1

A global vessel-position reporting system introduced 1 January 2008 in the wake of enhanced maritime security concerns. Required for all passenger ships + cargo ships > 300 GT operating in Areas A2, A3, or A4 (i.e. most SOLAS commercial tonnage). Ship-side equipment reports position via satellite to a national or regional LRIT Data Centre.

• Reporting frequency. Every 6 hours minimum by default; more frequent when the vessel is in a specific coastal-state area.
• Data content. Vessel ID, position, date/time of report. NOT cargo, crew, or destination.
• Access rules. Flag state has full access. Coastal states can access vessels within 1,000 nm of their coast. Port states can access vessels intending to enter their port. Search + Rescue authorities have global access.
• Confidentiality. Not public data. The LRIT International Data Exchange (IDE) hub is operated by EMSA on behalf of IMO.
• Comparison with AIS. AIS is short-range VHF broadcast used for collision avoidance + regional monitoring; LRIT is long-range satellite reporting for security + tracking. Both are complementary.

Ship Security Alert System (SSAS) — SOLAS XI-2/6

A covert distress-alert system by which the ship can send a security alert (e.g. under piracy or terrorist attack) to the flag state administration + designated Company Security Officer, without alerting the attackers on board. Required on passenger ships + all cargo ships > 500 GT.

• Activation. By a "panic-button" located discreetly on the bridge + typically a second in a hidden location. Activation must not produce any audible or visible signal on board.
• Recipient. Flag state + designated Company Security Officer (from ISPS Code). NOT MRCCs (that's the DSC or SART role).
• Data transmitted. Vessel ID, position, date/time. NOT audio or additional detail.
• Test rules. Test alerts are permitted but must be coordinated with the flag state + Company to avoid false-alert response.
• Real-world use. SSAS activation was used in Somali piracy incidents 2008-2013 + Houthi seizure of Galaxy Leader (2023).

Data-request procedure after casualty

Casualty investigators (typically the flag state Marine Casualty Investigation Board) can request:

1. VDR data. Directly from the vessel or the recovered capsule. Chain of custody must be preserved.
2. LRIT position history. From the flag-state LRIT Data Centre; typically the full voyage history.
3. SSAS activation records. From the flag state + Company records.

Any Master, DPA, or SSO should ensure the SMS documents the procedure for each — including who has authority to authorise data release.

See also

• · AIS — short-range broadcast counterpart to LRIT.
• · ISPS Code — SSAS parent framework.
• · GMDSS — distress alerts (DSC).
• · Accident investigation.

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