What the MAIB Is and Why It Matters to Command
The Marine Accident Investigation Branch (MAIB) is the UK's independent accident investigation authority. Its sole purpose is safety improvement, not apportionment of blame. As master, you are the reporting point — your obligations are statutory, not optional, and failure to report is a criminal offence.
The legal framework sits in the Merchant Shipping (Accident Reporting and Investigation) Regulations 2012 (SI 2012/1743). MSN 1858 gives operational guidance aligned to those Regulations and defines the categories you must distinguish.
The Three Categories You Must Distinguish
Very Serious Marine Casualty (VSMC) Involves loss of life, total loss of the ship, or severe damage to the environment. These are mandatory MAIB investigations.
Serious Casualty Includes: fire, explosion, collision, grounding, contact, heavy weather damage, structural failure, or flooding — where the result is death or serious injury to a person on board, significant pollution, or loss of the ship's seaworthiness. Imminent loss of life counts.
Marine Incident (formerly "accident" or "incident") A near-miss or situation that could have led to a casualty — no actual harm occurred but the potential was real.
Reporting: What, How Fast, and to Whom
| Category | Report to | Timescale |
|---|---|---|
| VSMC / Serious Casualty | MAIB immediately | As soon as practicable; phone first, written follows |
| Marine Incident | MAIB | Within 14 days |
The immediate notification is by telephone to the MAIB duty officer (24-hour line). A written report on Form MCA 5004 (MAIB accident report form) follows. Do not wait for the written form before making the phone call on a serious casualty.
Where a seafarer dies or goes missing, you must also notify the flag state and, in UK waters, the Receiver of Wreck as appropriate. The MAIB notification is separate from RIDDOR obligations ashore.
What the Master Must Preserve
Once you know an investigation is likely, preserve all voyage data recorder (VDR) or simplified VDR recordings, log books, charts in use, engine records, and GMDSS logs. Do not overwrite data or correct the deck log retrospectively. The MAIB has powers to require production of documents and to interview personnel.
The Examiner's Distinction Trap
Candidates confuse the MAIB with the MCA. The MCA is the regulator and enforcement body; the MAIB investigates independently and does not prosecute. A Port State Control officer is MCA/flag state — not MAIB. An MAIB inspector attends to find causal factors, not to initiate proceedings. Keep these roles clinically separate in your answers.