Flag State, class and ROs explained (RO Code, III Code)

Start here

A liferaft is due for service, the extension letter has not arrived, and the port State control officer (PSCO) wants to know why. The chief officer calls the class surveyor, who says it is a flag matter. The flag says it authorised the class society to deal with it. The superintendent says the ship’s manager handles flag correspondence. Everybody is partly right, and the ship is losing time.

Most confusion on board comes from not knowing which hat each organisation is wearing. A classification society can be doing two completely different jobs on the same ship on the same day: a class survey under its own rules, and a statutory survey as a recognised organisation (RO) on behalf of the flag State. This lesson sorts out who does what, which IMO instruments tie them together, and where each one’s responsibility stops.

Try it

Which body does this?

In plain words

Four groups look after a ship’s safety, and each one has a different job.

The flag State is the country whose flag the ship flies. It has signed the conventions (SOLAS, MARPOL, Load Lines, MLC and others), so it is responsible for making sure its ships meet them. It writes the national rules, issues or authorises the certificates, and answers to the IMO for how well it does this.

The classification society (class) writes technical rules for the hull, machinery and electrical systems, surveys ships against them and keeps them “in class”. Insurers, banks and charterers rely on class. SOLAS also expects ships to be designed, built and maintained to the structural, mechanical and electrical rules of a class society recognised by the flag.

The recognised organisation (RO) is usually a class society that the flag State has formally authorised to do statutory work on its behalf: surveying the ship for the SOLAS, Load Line and MARPOL certificates, and issuing them. When a class surveyor signs a SOLAS certificate, he or she is acting for the flag, not for the class society.

The port State is the country whose port the ship is visiting. It did not issue the certificates, but it is allowed to check that a foreign ship really matches them, and to stop it sailing if it does not.

And underneath all of them sits the company: the owner or manager that runs the ship. The surveyors and inspectors take snapshots. The company and the crew keep the ship safe every day in between.

In detail

The flag State and the III Code

The IMO Instruments Implementation Code (III Code), adopted by resolution A.1070(28) on 4 December 2013, sets out what flag, coastal and port States must do to implement IMO conventions. Its use is mandatory under SOLAS chapter XIII, and it is the standard against which States are audited in the IMO Member State Audit Scheme. For flag States it requires, among other things:

national laws and resources to administer safety and pollution prevention, and enough qualified surveyors;
when an RO is used, a formal written agreement, specific instructions on what to do when a ship is unfit to proceed to sea, and the national laws and interpretations the RO must apply (paragraph 18);
an oversight programme for its ROs, including the right to do supplementary surveys (paragraph 20);
measures to stop ships sailing until they comply, and periodic inspection of its own ships (paragraph 22);
oversight of corrective action when one of its ships is detained abroad (paragraph 25);
certificates issued only once the ship is found to meet all applicable requirements (paragraph 26);
minimum qualifications for flag State surveyors, such as a management-level certificate of competency with at least three years at sea as an officer, or a relevant engineering or science degree with three years’ relevant work (paragraphs 29 to 31);
evaluation of its own performance using indicators that include port State control detention rates (paragraph 43).

Recognised organisations and the RO Code

The Code for Recognized Organizations (RO Code), resolutions MSC.349(92) and MEPC.237(65), took effect on 1 January 2015 and is mandatory under SOLAS regulation XI-1/1, the 1988 Load Lines Protocol and MARPOL Annexes I and II. It has three parts:

Part	Content	Status
1	General: purpose, scope, delegation, communication to the IMO	Mandatory
2	Requirements for ROs and for flag States authorising them	Mandatory
3	Guidelines for flag State oversight of ROs	Recommended

Key points of part 2 for people on board:

The RO must publish its rules, with an English version (2.2).
The RO and its surveyors must be independent: they may not be the designer, manufacturer, supplier, installer, owner or maintainer of the item they certify (2.3).
Information on the status of ships certified by the RO must be public (2.8.3).
The RO must tell the flag about ships found unfit to proceed to sea, and make information on overdue surveys and conditions of class available to the flag on request (3.9.2).
Work done by sub-contractors or service suppliers counts as the RO’s own work. Firms working for the owner whose results the RO uses for statutory decisions (for example liferaft, fire-extinguishing system or lifeboat service providers) must be approved and controlled by the flag or the RO (5.9).

The flag must not authorise an RO beyond its capabilities, and it must deposit with the IMO the list of its ROs and the scope of their authority (part 1, sections 4 and 5). You can see each flag’s ROs and their scope in the IMO’s GISIS database, under recognised organisations.

Class and statutory work on the same ship

	Class survey	Statutory survey by the RO
Rules applied	The society’s own rules	Conventions and the flag’s national law
Acting for	The society (contract with the owner)	The flag State
Typical output	Class certificate, class status, conditions of class	SOLAS, Load Line and MARPOL certificates and endorsements
Who can grant extensions	The society, under its rules	The flag, or the RO only if authorised

The two are harmonised in practice: the Survey Guidelines say an extended statutory certificate should not run beyond the validity of the class certificate that documents the ship’s structural, mechanical and electrical compliance.

Classification societies in IACS

The International Association of Classification Societies (IACS) has 12 members: ABS, Bureau Veritas, China Classification Society, Croatian Register of Shipping, DNV, Indian Register of Shipping, Korean Register, Lloyd’s Register, ClassNK, Polish Register of Shipping, RINA and Türk Loydu. IACS writes common technical requirements (unified requirements and interpretations) that its members apply. Many flags also authorise ROs outside IACS.

Port State control

Port State control rests on the “control” regulations of each convention, for example SOLAS regulations I/19, XI-1/4 and XI-2/9, MARPOL article 5 and the MLC. A PSCO is “responsible exclusively” to the port State. Flags may entrust surveys to ROs, but only officers authorised by the port State may board, inspect and detain foreign ships. Ships of States not party to a convention get “no more favourable treatment”. Lesson 7 covers PSC in depth.

The company

The surveys and audits do not move responsibility away from the shipowner. The ISM guidelines for Administrations point out that maintaining the ship between surveys is not covered by statutory or class surveys, and that ISM verification does not relieve the company, the master or anyone else of their own responsibilities.

How the bodies fit together

Situation	First call	Also involve
Certificate about to expire away from the survey port	Flag (extension)	RO (recommendation, survey scope)
Damage after a contact or heavy weather	RO that issued the certificate, and flag	Class (condition of class), P&I
Equipment service by a service provider	Service provider approved by flag or RO	RO surveyor at the next survey
Ship detained in a foreign port	Flag and RO	Port State (re-inspection), company DPA

What the rules say

The RO Code defines a recognised organisation as an organisation “assessed by a flag State, and found to comply with this part of the RO Code” (part 2, 1.1).¹
The RO Code requires an RO and its staff not to be the designer, manufacturer, supplier, installer, owner, user or maintainer of the item they certify (part 2, 2.3).¹
The RO Code requires information on the status of ships certified by ROs to be made public (part 2, 2.8.3).¹
Part 2, 5.9.2 of the RO Code makes firms whose results the RO uses for statutory decisions subject to approval and control by the flag State or the RO.¹
The flag State must not authorise functions beyond an RO’s capabilities and must deposit the list of its ROs with the IMO (RO Code part 1, 4.2 and 5).¹
III Code paragraph 18 requires a flag using an RO to have a formal written agreement and to give specific instructions for ships found unfit to proceed to sea.²
III Code paragraph 20 requires the flag to run an oversight programme for its ROs, including supplementary surveys.²
III Code paragraph 26 states that certificates should only be issued once the ship has been found to meet all applicable requirements.²
The RO Code is mandatory under SOLAS regulation XI-1/1 and the III Code under SOLAS regulation XIII/2.⁴
The Procedures for Port State Control state that only officers duly authorised by the port State may board, inspect and detain foreign ships (paragraph 2.1.3) and that a PSCO is responsible exclusively to that Party (1.7.8).³
The Survey Guidelines recommend that an extended statutory certificate should not outlast the class certificate documenting structural, mechanical and electrical compliance (5.9.2.8).⁵

Flag and class notes

Each flag decides how much it delegates. Some authorise their ROs to issue almost every statutory certificate, others keep certain decisions (extensions, exemptions, equivalents, MLC or ISPS certification) for themselves. The scope is in the flag’s agreement with each RO, and the summary is lodged with the IMO and visible in GISIS.¹² Flags publish their rules and instructions to ROs as circulars, for example Panama’s Merchant Marine Circulars, which are addressed to ROs as well as owners.⁶ Ask the RO’s local office which items it may decide alone and which need the flag. For class, check the society’s rules for its survey scheme (continuous survey of machinery or hull, planned maintenance schemes) and the class status report, which lists surveys due and conditions of class.

Key numbers

What	Value
RO Code took effect	1 January 2015¹
Parts of the RO Code	3 (parts 1 and 2 mandatory, part 3 recommended)¹
III Code adopted	4 December 2013, resolution A.1070(28)²
Minimum sea service for a flag surveyor qualified as an officer	3 years as deck or engine officer²
IACS member societies	12⁷
Paris MoU ROs on the 2025 RO performance list	31 (minimum 60 inspections over three years)⁸

What inspectors find

Certificates signed by an RO for a scope that the flag did not authorise, or by an RO the flag no longer recognises. PSCOs check RO authorisation as part of the certificate check.³
Conditions of class or statutory conditions past their due date, which the RO must report to the flag on request.¹
Service certificates from a firm that is not approved by the flag or the RO, for example for liferafts or fixed fire-extinguishing systems.¹
No evidence that damage was reported to the flag or RO, so the PSC exemption for accidental damage does not apply.³
Flag circulars or national requirements not on board, or not known to the master, when the flag adds to the convention rules.

Questions people ask

Is the class surveyor working for the owner or for the flag?

Both, at different moments. For class surveys the society acts under its contract with the owner and its own rules. For statutory surveys it acts on the flag’s authority as an RO.

Can a port State officer overrule a certificate issued by the flag's RO?

A PSCO does not cancel the certificate. If the ship does not correspond substantially with its certificates, the PSCO can require rectification and detain the ship, and tells the flag and the RO.

Where can I check which ROs a flag recognises?

In the IMO’s GISIS database, in the module on recognised organisations, where flags record their ROs and the scope of authority.

Does the RO approve our service providers?

It can. Under the RO Code, service firms whose results the RO uses must be approved and controlled by the flag or the RO. Check that your provider’s approval covers the equipment, make and model.

Sources

1 IMO Resolution MSC.349(92), Code for Recognized Organizations (RO Code), adopted 21 June 2013, taking effect 1 January 2015, Annex, parts 1 to 3. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.349(92).pdf
2 IMO Resolution A.1070(28), IMO Instruments Implementation Code (III Code), adopted 4 December 2013, Part 2 (Flag States), paragraphs 15 to 44. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/AssemblyDocuments/A.1070(28).pdf
3 IMO Resolution A.1185(33), Procedures for Port State Control, 2023, paragraphs 1.4, 1.5, 1.7.8, 2.1.3 and 2.3.7 (superseded by resolution A.1206(34), Procedures for Port State Control, 2025, adopted 3 December 2025, with the core chapters unchanged). https://wwwcdn.imo.org/localresources/en/OurWork/IIIS/Documents/A%2033-Res.1185%20-%20PROCEDURES%20FOR%20PORT%20STATE%20CONTROL%2C%202023%20(Secretariat)%20(1).pdf
4 IMO Resolution A.1188(33), 2023 Guidelines on implementation of the International Safety Management (ISM) Code by Administrations, adopted 6 December 2023, Annex, paragraphs 1.3.2, 3.3.3 and 3.3.5. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/AssemblyDocuments/A.1188(33).pdf
5 IMO Resolution A.1207(34), Survey Guidelines under the Harmonized System of Survey and Certification (HSSC), 2025, Annex, paragraphs 4.7.2 and 5.9. https://wwwcdn.imo.org/localresources/en/OurWork/IIIS/Documents/A%2034-Res.1207%20-%20SURVEY%20GUIDELINES%20UNDER%20THE%20HARMONIZED%20SYSTEMOF%20SURVEY%20AND%20CERTIFICATION%20(HSSC),%202025%20(Secretariat).pdf
6 Panama Maritime Authority, Merchant Marine Circular MMC-379 (addressed to recognised organisations, owners and operators), updated July 2026. https://www.panamashipregistry.com/wp-content/uploads/2024/07/MMC-379-Procedure-for-PSC-2025-30-07-2026.pdf
7 International Association of Classification Societies, IACS members. https://iacs.org.uk/membership/iacs-members
8 IIMS, Rising detention rates and recurring areas of concern in Paris MoU Annual Report 2025 (July 2026), summarising the Paris MoU Annual Report 2025. https://www.iims.org.uk/rising-detention-rates-and-recurring-areas-of-concern-in-paris-mou-annual-report-2025/

Free awareness training. Al Safwan Marine is not an approved training provider, so no certificate is given, and these courses are not a qualification. They don't replace STCW training, manufacturer training or the certification technicians need for this work. The manufacturer's manual and your flag's rules always come first.

This lesson is also published by our sister site vslsafety.com.

Flag, class and recognised organisations: who does what