MASS Code: the New IMO Framework for Autonomous Ships
Adopted in May 2026, the first IMO Code for autonomous ships is still non-mandatory: but the path towards mandatory status in 2032 has already been mapped out, stage by stage.
Operational Explanation
During the 111th session of the Maritime Safety Committee (MSC 111, 13-22 May 2026), IMO adopted the first Code for Maritime Autonomous Surface Ships (MASS Code): a goal-based framework establishing that autonomous ships must be designed, constructed, operated and certified to safety and environmental-protection standards equivalent to those of conventional ships.
The Code was adopted as a non-mandatory instrument, entering into force on 1° July 2026 with a two-year voluntary introduction period. It applies to cargo ships subject to SOLAS Chapter I, generally ships of over 500 GT engaged on international voyages. The path towards mandatory status is already defined: in December 2026 (MSC 112) the framework for an Experience-Building Phase (EBP) of the non-mandatory Code will be developed; in 2028 development of the mandatory MASS Code will begin, based on the non-mandatory Code and the results of the EBP; adoption of the first mandatory MASS Code is expected by 1° July 2030, with entry into force expected on 1° January 2032.
Regulatory Reference
MASS Code, adopted at MSC 111 (May 2026): non-mandatory goal-based framework, in force from 1° July 2026, with a two-year voluntary introduction period. Applicable to SOLAS Chapter I cargo ships (generally >500 GT on international voyages). Path towards mandatory status: EBP defined at MSC 112 (December 2026), development of the mandatory Code from 2028, adoption expected by 1° July 2030, entry into force 1° January 2032.
Scope of Application
Autonomous cargo ships (Maritime Autonomous Surface Ships) subject to SOLAS Chapter I, generally of over 500 GT engaged on international voyages; Companies and flag Administrations considering voluntary adoption of the Code during the 2026-2028 introduction period.
Procedure / How to Complete It
- Check whether your fleet includes, or plans to include, autonomous ships within the scope of application of the MASS Code.
- For Companies interested in voluntary adoption, become familiar with the non-mandatory Code's goal-based framework, in force from July 2026.
- Monitor development of the framework for the Experience-Building Phase (EBP) expected from MSC 112 (December 2026), which will guide practical application of the Code during the voluntary period.
- Follow progress towards the mandatory MASS Code from 2028 onward, in view of the entry into force expected on 1 January 2032.
- Do not assume the Code is already mandatory: it remains a voluntary instrument until the regulatory path towards mandatory status is completed.
Practical Example
Example: a Company operating a pilot autonomous-ship project decides to voluntarily adopt the MASS Code from July 2026, aligning design and operating procedures with the goal-based framework, so as to gain useful experience ahead of the future Experience-Building Phase as well.
Real Cases
Common Mistakes Mistake Library
| Mistake | Consequence | How to avoid it |
|---|---|---|
| MASS Code considered already mandatory for all autonomous ships from 2026 | Incorrect regulatory planning, with expectations not matching the real regulatory status | Always clarify that the Code is non-mandatory until completion of the path towards mandatory status expected in 2032 |
| Regulatory path towards mandatory status not monitored by Companies with autonomous-ship projects under development | Unpreparedness for the requirements that will become mandatory from 2032 | Monitor the intermediate milestones (EBP 2026, development of the mandatory Code from 2028) for timely preparation |
| Code's scope of application misunderstood, applied also to ships not subject to SOLAS Chapter I | Compliance assessment not relevant to the real regulatory scope | Always verify that the ship falls within the scope of application (SOLAS Chapter I cargo ships, generally >500 GT) before assessing adoption of the Code |
PSC Observations
Operational Tips
- Do not confuse adoption of the MASS Code (May 2026) with its entry into force as a mandatory requirement: these are distinct phases of the regulatory path.
- If your Company operates or plans autonomous ships, actively monitor development of the Experience-Building Phase expected from MSC 112.
- Always verify the Code's specific scope of application (SOLAS Chapter I cargo ships, generally >500 GT) before assuming its relevance.
Checklist
- Relevance of the MASS Code to your fleet verified against the specific scope of application
- Non-mandatory status of the Code during the 2026-2028 introduction period clarified internally
- Development of the Experience-Building Phase (expected from MSC 112, December 2026) monitored
- Path towards the mandatory Code (from 2028, entry into force 2032) followed with lead time
- Voluntary adoption assessed for autonomous-ship projects under development