Definitions

The International Maritime Organization has conducted a Regulatory Scoping Exercise (IMO MSC.1-Circ.1638) which defines levels of autonomy (for seagoing ships) in four categories:

• 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 be 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. Seafarers are available on board to take control and to operate the shipboard systems and functions.
• 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.

The Central Committee for Navigation on the Rhine, during its plenary meeting in December 2018, issued a categorisation for inland shipping in six categories: 

• 0 – No automation: The full-time performance by the human boatmaster of all aspects of the dynamic navigation tasks, even when supported by warning or intervention systems, e.g. navigation with support from radar installation tasks. 
• 1 – Steering assistance: The context-specific performance by a steering automation system using certain information about the navigational environment and with the expectation that the human boatmaster performs all remaining aspects of the dynamic navigation tasks.  
• 2 – Partial automation: The context-specific performance by a navigation automation system of both steering and propulsion using certain information about the navigational environment and with the expectation that the human boatmaster performs all remaining aspects of the dynamic navigation tasks system. Performs all dynamic navigation tasks (when active). 
• 3 – Conditional automation: The sustained context-specific performance by a navigation automation system of all dynamic navigation tasks, including collision avoidance, with the expectation that the human boatmaster will be receptive to requests to intervene and to system failures and will respond appropriately. 
• 4 – High automation: The sustained context-specific performance by a navigation automation system of all dynamic navigation tasks and fallback performance, without expecting a human boatmaster to respond to a request to intervene. 
• 5 – Autonomous = full automation: The sustained and unconditional performance by a navigation automation system of all dynamic navigation tasks and fallback performance, without expecting a human boatmaster to respond to a request to intervene. 

Several class societies, including DNV (DNVGL-CG-0264), BV (NI641-R01) and LR are issuing guidelines on autonomous ships, each with subtly different definitions. For example, BV recognises degrees of automation as follows: 

• Degree A0 – Human-operated: The system or ship can perform information acquisition, but cannot analyse information, take decisions and/or execute operations on behalf of a human.  
• Degree A1 – Human-directed: The system or ship can perform information acquisition, information analysis and suggest actions, but cannot take decisions and/or execute operations on behalf of a human. The human makes decisions and takes actions. The human may be located aboard (crew) or remotely outside the ship in a remote-control centre (operator). 
• Degree A2 – Human-delegated: The system or ship can perform information acquisition, information analysis, take decisions and initiate actions, but requests human confirmation. System invokes functions waiting for human confirmation. The human can reject decisions. The human may be located aboard (crew) or remotely outside the ship in a remote-control centre (operator). 
• Degree A3 – Human-supervised: The system or ship can perform information acquisition, information analysis, take decisions and execute operations under human supervision. 
• Degree A4 – Full automation: Self-operating system or ship under defined conditions and in specific circumstances. 

Several other definitions and categorisations exist, but here we shall only mention the generic categorisation proposed by SmartPort in their white paper on Smart Shipping: 

• 0 – Current status – human-operated; 
• 1 – Increased sensors and decision support. Humans are still in control; 
• 2 – Human-assisted autonomy (with or without remote control as backup). Humans are in the loop for complex operations and continuous monitoring; 
• 3 – Fully autonomous. Humans normally not in the loop, except in emergencies.