Experience Building Phase
IMO MASS Code's 2026-2030 non-mandatory trial period before autonomous shipping rules become compulsory.
The IMO's Experience Building Phase began on 1 July 2026 as the non-mandatory trial period of the new MASS Code, with its detailed framework deferred to December 2026.
Last refreshed: 24 July 2026
Will the data gathered in the Experience Building Phase make or break autonomous shipping by 2032?
Timeline for Experience Building Phase
Crewless-ship rules duck the hard part
Autonomous Systems: Land & SeaMentioned in: The MASS Code enters force, its detail deferred
Autonomous Systems: Land & SeaMentioned in: Milrem leaves Paris with intent only
Autonomous Systems: Land & SeaBackground
The Experience Building Phase (EBP) is the initial non-mandatory period of the IMO's Maritime Autonomous Surface Ships (MASS) Code, which entered into force on 1 July 2026. During the EBP, flag states, port states and shipping operators may voluntarily apply the Code's safety framework to autonomous and remotely operated ships in international waters, without a legal requirement to comply, so that real-world data can be gathered before a mandatory regime is considered.
The IMO adopted the MASS Code at MSC 111 in May 2026 after more than five years of regulatory scoping. The Code covers four degrees of autonomy, from automated decision-support tools through to fully autonomous vessels with no seafarers aboard.
The EBP's own governing framework is due at MSC 112 in December 2026, ahead of a targeted mandatory-adoption date of 1 July 2030 and SOLAS amendments planned for 1 January 2032.
Its framework waits for December
The Experience Building Phase (EBP) opened on 1 July 2026 as the voluntary trial period of the IMO's Maritime Autonomous Surface Ships Code, letting flag states, port states and operators apply the Code's safety framework without a legal obligation to do so.
The EBP's own operating framework will not be built until the Maritime Safety Committee meets in December 2026, leaving open the questions that will determine how it works in practice: liability for a shore-based master during a casualty, and whether one master can safely oversee several ships. Lloyd's Register and Norway's classification body have each published assurance frameworks to fill that gap in the meantime.
What is the IMO MASS Code Experience Building Phase?
When will autonomous ship rules become mandatory under IMO?
What degrees of ship autonomy does the MASS Code cover?
