What must be investigated, and by whom
The Code requires a marine safety investigation into every very serious marine casualty. The Code defines that term precisely: a marine casualty involving the total loss of the ship, a death, or severe damage to the environment. For other casualties and incidents, including groundings, collisions, fires, injuries and near misses with serious potential, an investigation is recommended where lessons are likely. The Code is split. Parts I and II are mandatory through SOLAS. Part III sets out recommended practices. Knowing which is which matters when an administration is deciding how far to go. Primary responsibility sits with the flag State. The Code recognises that casualties are rarely tidy jurisdictionally. Substantially interested States take part through consultation and cooperation provisions, and States may agree between themselves who leads. The category is wider than it first looks. It covers the flag State of a ship involved, the State in whose internal waters or territorial sea the casualty occurred, a State whose environment or coastal interests were seriously harmed or threatened, a State whose nationals lost their lives or were seriously injured, a State holding information the investigating States consider useful, and any other State that establishes an interest the investigating States consider significant. Findings feed the IMO's global casualty database, which is how one operator's bad day becomes the industry's lesson.
No-blame in practice
The Code separates the safety investigation from criminal, civil and disciplinary processes. Investigators look for causes across the whole chain: human factors, management and the safety management system, equipment, design, weather and commercial pressure. Their reports draw safety conclusions and recommendations rather than verdicts. The separation is not absolute, and it is worth being clear about that. The Code says the safety investigation should be separate from and independent of other forms of investigation, and it does not prevent parallel civil, criminal or administrative proceedings. It also tells investigators not to hold back from fully reporting causal factors merely because blame or liability might be inferred from them. The protection given to what seafarers say is weaker than it is often described. The Code recommends, in Part III, that marine safety records should not be disclosed in criminal, civil, disciplinary or administrative proceedings unless the public interest in justice outweighs the harm to future investigations. That protection is a recommended practice, not a mandatory requirement. The mandatory chapters require only that seafarers be informed of the risk of self-incrimination and given access to legal advice. Anyone planning on the assumption that an interview is privileged should check what the investigating State has actually adopted. The companion principle is the fair treatment of seafarers. Crews caught in a casualty face detention, questioning and blame in multiple jurisdictions. The IMO and ILO guidelines on fair treatment of seafarers in the event of a maritime accident exist because how people are treated after an accident determines whether the industry hears the truth about the next one. A separate set of IMO and ILO guidelines, finalised in 2024, addresses seafarers detained in connection with alleged crimes.
What a good investigation looks for
Serious investigations work backward from the event through the layers that allowed it. First the act or failure at the sharp end. Then the conditions that shaped it: fatigue, training, manning, the state of the equipment. Then the organisational decisions behind those conditions, including maintenance budgets, safety culture and the gap between written procedures and actual practice. The recurring finding across decades of reports is that casualties are organisational long before they are mechanical. That is exactly the ISM Code's premise, restated by the evidence every year.
The operator's role, before and after
For a company, casualty readiness is part of emergency preparedness. Preserve evidence, and voyage data recorder data above all. Give masters clear guidance on cooperating with investigators. Coordinate legal and P&I input so that it supports the safety process rather than suffocating it. Look after the crew. Afterward, the measure of a serious operator is what changes. Investigation findings and recommendations, both its own and the industry's, should flow into the safety management system as revised procedures, training and design decisions, with named owners and dates. The Code can only produce lessons. Only operators can decide to learn them.