For the continuously manned bridge, we have defined two possible types of "autonomy":• Direct control. The crew on the bridge is continuously in control of operations, although simple automation, e.g. autopilot, or advanced decision support functions may be in use. This is strictly speaking not an autonomy type, but is included in the taxonomy for completeness.• Automatic bridge. The bridge system controls the ship while crew on the bridge continuously monitors the situation and can intervene at any time. The level of automation may be arbitrarily high, but crew is always ready to intervene.For the fully or periodically unmanned systems, there are four autonomy types where the ship must operate reliably without humans on the bridge: