By Roly McKie, IMRF IMO Representative and SAR Advisor

Maritime Autonomous Surface Ships (MASS) is an acronym used by the International Maritime Organization (IMO) to describe commercial vessels that operate with little or no human intervention, using sensors, software, and communication systems to navigate, avoid collisions and perform the tasks and functions of the vessel. 

This article discusses the implications for  search and rescue caused by the introduction of commercial MASS and remotely operated vessels and craft. It does not consider the use of autonomous or remotely operated rescue craft or vessels by lifeboat or rescue boat organisations. The IMRF members will look to consider this issue and it will be a point of discussion in future articles, webinars, and the IMRF’s Global Maritime SAR Forum.[1]


The IMO has determined four degrees of MASS:

- Degree one: Ship with automated processes and decision support. Seafarers are on board to operate and control shipboard systems and functions. Some operations may be automated and, at times, unsupervised, but with seafarers on board ready to take control.

- Degree two: Remotely controlled ship with seafarers on board. The ship is controlled and operated from another location, but seafarers are on board.

- Degree three: Remotely controlled ship without seafarers on board. The ship is controlled and operated from another location. There are no seafarers on board.

- Degree four: Fully autonomous ship. The operating system of the ship is able to make decisions and determine actions by itself.


Further IMO information on MASS can be found here: Autonomous shipping (

Through Maritime Rescue Coordination Centres (MRCC), the global SAR system relies heavily on passing ships to assist with SAR – a commercial ship may be the nearest ‘rescue unit’. In some areas of the world, the only ‘SAR response’ available may be from ships and other local vessels, e.g., fishing boats.

Autonomous, semi-autonomous and remotely operated vessels will bring a new paradigm to SAR, depending on how many vessels are MASS in the future.

Benefits and Challenges of MASS for the Shipping Industry

MASS has the potential to offer several benefits for the maritime sector, such as:

- Reducing operational costs by eliminating or reducing crew expenses, such as salaries, accommodation, food, and training.

- Enhancing safety by reducing human errors, fatigue, and accidents, especially in harsh or hazardous environments.

- Improving efficiency and environmental performance by optimising routes, speed, and fuel consumption, as well as reducing emissions and noise.

- Increasing flexibility and scalability by enabling new services, such as on-demand delivery, short-sea shipping, persistence, and offshore support.

Current Status and Future Outlook

MASS are still in the early stages of development and testing, but several projects and initiatives have been launched worldwide to advance the technology and demonstrate its feasibility.

MASS will likely become more prevalent and sophisticated in the coming years as technology improves and regulations evolve.


How MASS could affect SAR at sea

SAR operations are often challenging, costly and risky, especially in remote or harsh environments. Human errors or faults, such as negligent lookout, poor communication, or fatigue, are common causes of marine accidents that require SAR intervention. Moreover, SAR responders face dangers, like rough seas, extreme weather, low temperatures, etc.

MASS could potentially improve the efficiency, effectiveness, and safety of SAR operations by:

- Reducing response time: a commercial MASS might be near the scene of a SAR incident (as is the case for crewed vessels now) and, using communications automation, will be continually ‘listening for’ and can receive distress alerts instantly and then rapidly retransmit them to the shore operations team and/or MRCC.

- Enhancing situational awareness: MASS will be equipped with advanced sensors, such as radar, LIDAR, sonar, high-resolution video cameras, and infrared and night vision systems that could provide real-time information about the environment and assist in SAR and the location of survivors. MASS could communicate and coordinate with each other and with other platforms, such as satellites or drones, to form a networked system that could cover a larger search area and share data.

- Minimising the risks to human lives: MASS might be able to operate in dangerous conditions that would be risky for crewed vessels, such as rough seas, storm conditions, chemical or fire hazards or where SAR incidents are going to be of long duration which would fatigue human crew: the persistence and untiring characteristics of MASS and its automatic systems will be one key advance for SAR.

However, MASS also poses some challenges and limitations for SAR, such as:

- Legal and regulatory issues: The current legal framework for maritime transport assumes seafarers are on board to operate and control shipboard systems and functions. Therefore, using MASS for SAR purposes may require adaptations or amendments to existing conventions and regulations, such as liability, insurance, registration, testing of capabilities and crewing.

- Technical and operational issues: The reliability and security of MASS depend on the performance and robustness of their systems and components, such as propulsion, navigation, communication, or power. Therefore, MASS may face technical failures or malfunctions that could compromise their functionality, performance (in SAR and normal operations) or safety.

- Ethical and social issues: The use of MASS for SAR purposes may raise ethical and social questions about the role and responsibility of humans in life-saving situations. For example, who should make the decisions about prioritising or allocating resources when there are multiple casualties? How should MASS interact with survivors needing emotional support or medical assistance?


The IMO has recently published its first draft of Consideration of Proposals for further development of the Draft Mass Code

It states:



10.1.1 Goal The goal of this part is to ensure that MASS fulfil the duties and tasks of any vessel under the International Law regarding distress situations, taking into account the mode of operation of the MASS. These duties and tasks can be summed up to three: duty to render assistance and to proceed to rescue persons in distress at all possible speed, duty to co-ordinate with the SAR services of the coastal State, and to render assistance requested by the coastal State.


10.1.2 Functional requirements:

In order to achieve the above mentioned goal, set out in paragraph 3.10.1 above, the following functional requirements are embodied in the provisions of this chapter:

FR 10.1.1 Every MASS in position to be able to provide assistance and receiving information from any source of persons in distress at sea, is bound to render assistance in so far as such action may reasonably be expected and can do so without serious danger to the ship or the crew or the passengers.

FR 10.1.2 Having account of the previous FR, every MASS should proceed with all possible speed to the rescue of persons in distress.

FR 10.1.3 Keeping in mind its operational limitations, every MASS will be at the disposal of the search and rescue service responsible for the SAR operation the MASS is involved in, except if its participation is deemed not necessary.

FR 10.1.4 After a collision, every MASS should render assistance to the other ship, its crew and its passengers, and provide the other vessel with the name of the vessel, its port of registry and the next port of call.

FR 10.1.5 A MASS master should lead SAR activities onboard in case of distress. A MASS master should have, according to international Law, the authority and responsibility to make decisions concerning safety and security of the ship, including to cooperate with SAR services of the coastal state concerned.


Electronic Systems for MASS Navigation and Operations

One key aspect of MASS is electronic systems that enable their autonomy. These systems can be divided into four main categories: sensing, communication, decision-making, and actuation.

Sensing systems collect data from the environment and the vessel itself. They include sensors such as cameras, radars, lidars, sonars, GPS, Inertial Measurement Units, and others. These provide information about the position, speed, heading, attitude, and status of the vessel, as well as the obstacles, objects, traffic, weather, and sea conditions around it.

Communication systems for transmitting and receiving data to and from other entities include  radios, satellites, cellular networks, Wi-Fi, and optical links. This enables the exchange of information between the vessel and other vessels, shore stations, or human operators. Communication systems are essential for coordination, navigation, collision avoidance, SAR, and remote control of MASS.

Decision-making systems for processing the data from the sensing and communication systems and generating commands for the vessel include computers, software algorithms, artificial intelligence, and machine learning. These systems enable the vessel to plan its route, execute its mission, react to unexpected situations, and learn from its experience.

Actuation systems for executing the commands from the decision-making systems and controlling the physical components of the vessel include motors, propellers, rudders, thrusters, valves, pumps, and others. These systems enable the vessel to move, steer, stop, adjust its buoyancy, and perform other actions.

The electronic systems of MASS are complex and interdependent. They require high levels of integration, reliability, security, and adaptability. They must also comply with international standards and regulations that ensure their safety and compatibility with other maritime systems. Developing these systems is challenging and an ongoing task that requires multidisciplinary collaboration and innovation.


The IMRF is considering the needs of the global SAR system regarding MASS. MRCCs rely heavily on passing ships to assist in SAR operations and nearly all SAR outside of coastal areas is carried out by available ships that are contacted by MRCCs or Coast Radio Stations (CRS) and asked to divert and assist.

The IMRF has submitted a Working Paper to the ICAO-IMO SAR Joint Working Group, which meets in Cape Town in November 2023, outlining the IMRF’s view of what functions and capabilities should be required of MASS to ensure effective and improved SAR globally.

The IMRF’s view is MASS and remotely operated vessels should have on-board capabilities to ensure that SAR can be reliably carried out and SAR using MASS would be improved by adding new technologies that would increase the success of maritime SAR. One particular concern is how an autonomous or semi-autonomous vessel would recover survivors and care for them if there are very few or no crew on board.

The IMRF’s IMO representative will keep members updated on this subject following the meeting of the SAR JWG.

[1] Members-only, online, monthly meeting to discuss SAR issues.