Not Under Command (NUC) (NUC)

A vessel unable through exceptional circumstances to manoeuvre as required by the collision regulations and therefore unable to keep out of the way of another vessel.

The status concerns actual inability, not merely inconvenience, restricted visibility, difficult handling or a voluntary decision to stop. Causes can include steering or propulsion failure or another exceptional loss of manoeuvring capability, assessed against what the regulations require in the encounter.

A NUC vessel displays the prescribed lights and shapes and, where applicable, sound signals, but those signals do not create absolute immunity from collision-avoidance duties. Other vessels must identify the situation and act under the complete rules, while the NUC vessel takes any action it remains able to take.